ORCID Profile
0000-0003-1522-4691
Current Organisations
Royal Women's Hospital
,
Murdoch Children's Research Institute
,
Royal Children's Hospital Melbourne
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Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.PEDIATRNEUROL.2005.01.002
Abstract: This report presents two neonates with nonketotic hyperglycinemia in whom conventional magnetic resonance imaging revealed structural cerebral abnormalities, diffusion-weighted imaging indicated abnormalities of myelinated white matter, and magnetic resonance spectroscopy provided biochemical evidence of elevated cerebral glycine levels. The early use of combined magnetic resonance modalities in these severely affected infants helped in prognostication and clinical management.
Publisher: American Thoracic Society
Date: 06-2021
Publisher: American Physiological Society
Date: 02-2014
DOI: 10.1152/JAPPLPHYSIOL.01142.2013
Abstract: The interrelationship between the role of surfactant and a sustained inflation (SI) to aid ex utero transition of the preterm lung is unknown. We compared the effect of surfactant administered before and after an initial SI on gas exchange, lung mechanics, spatial distribution of ventilation, and lung injury in preterm lambs. Gestational-age lambs (127 days 9 per group) received 100 mg/kg of a surfactant (Curosurf) either prior (Surf+SI) or 10 min after birth (SI+Surf). At birth, a 20-s, 35 cmH 2 O SI was applied, followed by 70 min of positive pressure ventilation. Oxygenation, carbon dioxide removal, respiratory system compliance, end-expiratory thoracic volume (via respiratory inductive plethysmography), and distribution of end-expiratory volume and ventilation (via electrical impedance tomography) were measured throughout. Early markers of lung injury were analyzed using quantitative RT-PCR. During the first 15 min, oxygenation, carbon dioxide removal, and compliance were better in the Surf+SI group (all P 0.05). End-expiratory volume on completion of the sustained inflation was higher in the Surf+SI group than the SI+Surf group 11 ± 1 ml/kg vs. 7 ± 1 ml/kg (mean ± SE) ( P = 0.043 t-test), but was not different at later time points. Although neither achieved homogenous aeration, spatial ventilation was more uniform in the Surf+SI group throughout 50.1 ± 10.9% of total ventilation in the left hemithorax at 70 min vs. 42.6 ± 11.1% in the SI+Surf group. Surf+SI resulted in lower mRNA levels of CYR61 and EGR1 compared with SI+Surf ( P 0.001, one-way ANOVA). Surfactant status of the fetal preterm lung at birth influences the mechanical and injury response to a sustained inflation and ventilation by changing surface tension of the air/fluid interface.
Publisher: Elsevier BV
Date: 11-2017
Publisher: BMJ
Date: 24-06-2022
DOI: 10.1136/ARCHDISCHILD-2022-323900
Abstract: Effective lung protective ventilation requires reliable, real-time estimation of lung volume at the bedside. Neonatal clinicians lack a readily available imaging tool for this purpose. To determine the ability of lung ultrasound (LUS) of the dependent region to detect real-time changes in lung volume, identify opening and closing pressures of the lung, and detect pulmonary hysteresis. LUS was performed on preterm lambs (n=20) during in vivo mapping of the pressure-volume relationship of the respiratory system using the super-syringe method. Electrical impedance tomography was used to derive regional lung volumes. Images were blindly graded using an expanded scoring system. The scores were compared with total and regional lung volumes, and differences in LUS scores between pressure increments were calculated. Changes in LUS scores correlated moderately with changes in total lung volume (r=0.56, 95% CI 0.47-0.64, p .0001) and fairly with right whole (r=0.41, CI 0.30-0.51, p .0001), ventral (r=0.39, CI 0.28-0.49, p .0001), central (r=0.41, CI 0.31-0.52, p .0001) and dorsal (r=0.38, CI 0.27-0.49, p .0001) regional lung volumes. The pressure-volume relationship of the lung exhibited hysteresis in all lambs. LUS was able to detect hysteresis in 17 (85%) lambs. The greatest changes in LUS scores occurred at the opening and closing pressures. LUS was able to detect large changes in total and regional lung volume in real time and correctly identified opening and closing pressures but lacked the precision to detect small changes in lung volume. Further work is needed to improve precision prior to translation to clinical practice.
Publisher: Springer Science and Business Media LLC
Date: 29-02-2016
Publisher: Wiley
Date: 09-2012
DOI: 10.1111/J.1440-1754.2012.02532.X
Abstract: The lungs of an extremely preterm infant ≤28 weeks gestation are structurally and biochemically immature and vulnerable to injury from positive pressure ventilation. A lung protective approach to respiratory support is vital, aiming to ventilate an open lung, using the lowest pressure settings that maintain recruitment and oxygenation and avoiding hyperinflation with each tidal breath. For infants with severe respiratory distress syndrome and persistent atelectasis, lung protective ventilation requires recruitment using stepwise pressure increments, followed by reduction in ventilator pressures in search of an optimal point at which to maintain ventilation. Several studies, including a single randomised controlled trial, have found this lung protective strategy to be more effectively administered using high-frequency oscillatory ventilation rather than conventional ventilation. Many extremely preterm infants have minimal atelectasis and low oxygen requirements in the first days of life, and the ventilatory approach in this case should be one of avoidance of factors including overdistension that are known to contribute to later pulmonary deterioration. From a practical perspective, this means setting positive end-expiratory pressure at the lowest value that maintains oxygenation and restricting tidal volume using a volume-targeted mode of ventilation.
Publisher: American Thoracic Society
Date: 15-04-2021
Publisher: Wiley
Date: 30-03-2015
DOI: 10.1002/PPUL.23187
Abstract: Synchronised intermittent mandatory ventilation (SIMV) and high-frequency jet ventilation (HFJV) are accepted ventilatory strategies for treatment of respiratory distress syndrome (RDS) in preterm babies. We hypothesised that SIMV and HFJV both facilitate adequate oxygenation and ventilation but that HFJV is associated with less lung injury. There were no differences in arterial oxygenation or partial pressure of carbon dioxide despite lower mean airway pressure during SIMV for most of the study. There were no consistent significant differences in end systolic and end diastolic PBF, lung injury data and static lung compliance. Preterm lambs of anaesthetised ewes were instrumented, intubated and delivered by caesarean section after intratracheal suction and instillation of surfactant. Each lamb was managed for 3 hr according to a predetermined algorithm for ventilatory support consistent with open lung ventilation. Pulmonary blood flow (PBF) was measured continuously and pulsatility index was calculated. Ventilatory parameters were recorded and arterial blood gases were measured at intervals. At postmortem, in situ pressure-volume deflation curves were recorded, and bronchoalveolar lavage fluid and lung tissue were obtained to assess inflammation. SIMV and HFJV have comparable clinical efficacy and ventilator pressure requirements when applied with a targeted lung volume recruitment strategy.
Publisher: Springer Science and Business Media LLC
Date: 26-11-2011
DOI: 10.1007/S00134-011-2421-Z
Abstract: Diagnosis of pneumothorax relies on clinical suspicion and chest X-ray, and is often delayed. We aimed to determine whether electrical impedance tomography (EIT) can accurately identify the presence of surgically created pneumothoraces before significant changes in clinical parameters. Six anesthetized and muscle-relaxed piglets with surfactant-depleted lungs were studied. Following chest drain insertion into the right ventral chest, 10-20 ml aliquots of air were instilled into the pleural space to a maximum volume of 200 ml. The pneumothorax was drained by attaching a Heimlich valve to the chest drain. At each instillation and after draining the pneumothorax, global and regional end-expiratory intra-thoracic volumes (EEV) were measured using respiratory inductive plethysmography (RIP) and EIT concurrently with [Formula: see text], heart rate and blood pressure. A significantly greater change in both global EEV(RIP) and EEV within the right ventral quadrant was seen at all volume instillations, from as little as 10 ml, compared with all other quadrants. There was no difference in EEV within the left ventral and both dorsal quadrants. Sp(O)(2) fell below 90% at 100 ml instillation. Tachycardia occurred at 140 ml instillation. EIT identified a 60% resolution of pneumothoraces within 60 s of attachment of the Heimlich valve. EIT accurately detects very small pneumothoraces before physiological parameters change.
Publisher: Cold Spring Harbor Laboratory
Date: 08-09-2022
DOI: 10.1101/2022.09.06.506865
Abstract: Bronchopulmonary disease is the chronic manifestation of the acute injury that may accompany ventilation following preterm birth. A lack of clear trial evidence often h ers clinical decision-making during support of the preterm lung at birth. Protein biomarkers have been used to define acute lung injury phenotypes and improve patient selection for specific interventions in adult respiratory distress syndrome. Here we present a mass spectrometry-based approach to profile the protein phenotype associated with three different aeration strategies known to cause different pathophysiological responses when applied at birth to preterm lambs. We were able to identify pathway enrichments specific to both ventilation strategy and lung regions based upon gravity-dependency. Ventilation strategy-specific phenotypes were further delineated by applying partial least square modelling to identify associations between specific proteins and clinical, physiological and morphological outcomes. This work highlights the specificity of lung injury responses to routinely applied birth interventions such as different respiratory support approaches and identified the molecular events associated with each. Furthermore, we demonstrate the capacity to sub ide preterm infants by the direct aetiology and response to lung injury the first step towards true precision medicine in neonatology.
Publisher: American Physiological Society
Date: 10-2022
DOI: 10.1152/AJPLUNG.00047.2022
Abstract: Positive end-expiratory pressure (PEEP) is critical to the preterm lung at birth, but the optimal PEEP level remains uncertain. The objective of this study was to determine the effect of maximum PEEP levels at birth on the physiological and injury response in preterm lambs. Steroid-exposed preterm lambs (124–127 days gestation n = 65) were randomly assigned from birth to either 1) positive pressure ventilation (PPV) at 8 cmH 2 O PEEP or 3-min dynamic stepwise PEEP strategy (DynPEEP), with either 2) 20 cmH 2 O maximum PEEP (10 PEEP second steps) or 3) 14 cmH 2 O maximum PEEP (20-s steps), all followed by standardized PPV for 90 min. Lung mechanics, gas exchange, regional ventilation and aeration (electrical impedance tomography), and histological and molecular measures of lung injury were compared between groups. Dynamic compliance was greatest using a maximum 20 cmH 2 O (DynPEEP). There were no differences in gas exchange, end-expiratory volume, and ventilator requirements. Regional ventilation became more uniform with time following all PEEP strategies. For all groups, gene expression of markers of early lung injury was greater in the gravity nondependent lung, and inversely related to the magnitude of PEEP, being lowest in the 20 cmH 2 O DynPEEP group overall. PEEP levels had no impact on lung injury in the dependent lung. Transient high maximum PEEP levels using dynamic PEEP strategies may confer more lung protection at birth.
Publisher: BMJ
Date: 29-08-2022
DOI: 10.1136/ARCHDISCHILD-2022-324282
Abstract: Mechanisms of non-invasive high-frequency oscillatory ventilation (nHFOV) in preterm infants are unclear. We aimed to compare lung volume changes during apnoeas in preterm infants on nHFOV and nasal continuous positive airway pressure (nCPAP). Analysis of electrical impedance tomography (EIT) data from a randomised crossover trial comparing nHFOV with nCPAP in preterm infants at 26–34 weeks postmenstrual age. EIT data were screened by two reviewers to identify apnoeas ≥10 s. End-expiratory lung impedance (EELI) and tidal volumes (V T ) were calculated before and after apnoeas. Oxygen saturation (SpO 2 ) and heart rate (HR) were extracted for 60 s after apnoeas. In 30 preterm infants, 213 apnoeas were identified. During apnoeas, oscillatory volumes were detectable during nHFOV. EELI decreased significantly during apnoeas (∆EELI nCPAP: −8.0 (−11.9 to −4.1) AU/kg, p .001 ∆EELI nHFOV: −3.4 (−6.5 to −0.3), p=0.03) but recovered over the first five breaths after apnoeas. Compared with before apnoeas, V T was increased for the first breath after apnoeas during nCPAP (∆V T : 7.5 (3.1 to 11.2) AU/kg, p=0.001). Falls in SpO 2 and HR after apnoeas were greater during nCPAP than nHFOV (mean difference (95% CI): SpO 2 : 3.6% (2.7 to 4.6), p .001 HR: 15.9 bpm (13.4 to 18.5), p .001). Apnoeas were characterised by a significant decrease in EELI which was regained over the first breaths after apnoeas, partly mediated by a larger V T . Apnoeas were followed by a considerable drop in SpO 2 and HR, particularly during nCPAP, leading to longer episodes of hypoxemia during nCPAP. Transmitted oscillations during nHFOV may explain these benefits. ACTRN12616001516471.
Publisher: BMJ
Date: 02-2019
DOI: 10.1136/ARCHDISCHILD-2018-316240
Abstract: The influence of pressure strategies to promote lung aeration at birth on the subsequent physiological response to exogenous surfactant therapy has not been investigated. To compare the effect of sustained inflation (SI) and a dynamic positive end-expiratory pressure (PEEP) manoeuvre at birth on the subsequent physiological response to exogenous surfactant therapy in preterm lambs. Steroid-exposed preterm lambs (124–127 days’ gestation n=71) were randomly assigned from birth to either (1) positive-pressure ventilation (PPV) with no recruitment manoeuvre (2) SI until stable aeration or (3) 3 min dynamic stepwise PEEP strategy (maximum 14–20 cmH 2 O dynamic PEEP (DynPEEP)), followed by PPV for 60 min using a standardised protocol. Surfactant (200 mg/kg poractant alfa) was administered at 10 min. Dynamic compliance, gas exchange and regional ventilation and aeration characteristics (electrical impedance tomography) were measured throughout and compared between groups, and with a historical group (n=38) managed using the same strategies without surfactant. Compliance increased after surfactant only in the DynPEEP group (p .0001, repeated measures analysis of variance), being 0.17 (0.10, 0.23) mL/kg/cmH 2 O higher at 60 min than the SI group. An SI resulted in the least uniform aeration, and unlike the no-recruitment and DynPEEP groups, the distribution of aeration and tidal ventilation did not improve with surfactant. All groups had similar improvements in oxygenation post-surfactant compared with the corresponding groups not treated with surfactant. A DynPEEP strategy at birth may improve the response to early surfactant therapy, whereas rapid lung inflation with SI creates non-uniform aeration that appears to inhibit surfactant efficacy.
Publisher: Wiley
Date: 12-08-2019
DOI: 10.1111/PAN.13707
Abstract: Tight control of tidal volume using accurate monitoring may improve neonatal outcomes. However, respiratory function monitors incorporated in current anesthetic workstations are generally inaccurate at tidal volumes used for infants. To determine if a specific respiratory function monitor for neonatal infants improved expired tidal volume delivery during anesthesia. Infants <3 months old requiring intubation for surgery in the operating theater were studied. After intubation a Phillips NM3, Acutronic Florian, or Novametrix Ventcheck Respiratory Function Monitor was integrated into the circuit, and clinicians given access to the display for the duration of anesthesia. Breath-to-breath expired tidal volume delivery, leak, and delivered pressure were recorded, with cardiorespiratory parameters. These were compared with a matched control group with clinicians blinded to respiratory function monitor display. A total of 10 055 and 2569 inflations were measured in the respiratory function monitor visible (n = 32) and masked (n = 33) groups, respectively, with mean (standard deviation) delivered expired tidal volume 7.5 (2.4) mL/kg and 7.7 (3.0) mL/kg, respectively mean difference (95% confidence interval) -0.2 (-1.1, 0.8) mL/kg (Welch's t test). In the visible group, 55.6% of expired tidal volumes were between 4 and 8 mL/kg compared to 51.7% in the masked group relative benefit (95% confidence interval), 1.08 (1.03, 1.12). Expired tidal volume was less likely to be 10 mL/kg 13.0% vs 22.0%, 1.11 (1.09, 1.14). Tidal volumes 10 mL/kg are frequently delivered during neonatal anesthesia. The inclusion of an accurate respiratory function monitor may reduce the risk of exposure to potentially harmful tidal volumes.
Publisher: Springer Science and Business Media LLC
Date: 11-02-2016
DOI: 10.1038/PR.2016.25
Abstract: To describe the interrelationship between antenatal steroids, exogenous surfactant, and two approaches to lung recruitment at birth on oxygenation and respiratory system compliance (Cdyn) in preterm lambs. Lambs (n = 63 gestational age 127 ± 1 d) received either surfactant at 10-min life (Surfactant), antenatal corticosteroids (Steroid), or neither (Control). Within each epoch lambs were randomly assigned to a 30-s 40 cmH2O sustained inflation (SI) or an initial stepwise positive end-expiratory pressure (PEEP) open lung ventilation (OLV) maneuver at birth. All lambs then received the same management for 60-min with alveolar-arterial oxygen difference (AaDO2) and Cdyn measured at regular time points. Overall, the OLV strategy improved Cdyn and AaDO2 (all epochs except Surfactant) compared to SI (all P < 0.05 two-way ANOVA). Irrespective of strategy, Cdyn was better in the Steroid group in the first 10 min (all P < 0.05). Thereafter, Cdyn was similar to Steroid epoch in the OLV + Surfactant, but not SI + Surfactant group. OLV influenced the effect of steroid and surfactant (P = 0.005) on AaDO2 more than SI (P = 0.235). The antenatal state of the lung influences the type and impact of a recruitment maneuver at birth. The effectiveness of surfactant maybe enhanced using PEEP-based time-dependent recruitment strategies rather than approaches solely aimed at initial lung liquid clearance.
Publisher: American Thoracic Society
Date: 09-2019
Publisher: Springer Science and Business Media LLC
Date: 18-08-2022
DOI: 10.1038/S41372-022-01484-5
Abstract: To determine the relationship between number of attempts and adverse events during neonatal intubation. A retrospective study of prospectively collected data of intubations in the delivery room and NICU from the National Emergency Airway Registry for Neonates (NEAR4NEOS) in 17 academic centers from 1/2016 to 12/2019. We examined the association between tracheal intubation attempts [1, 2, and ≥3 (multiple attempts)] and clinical adverse outcomes (any tracheal intubation associated events (TIAE), severe TIAE, and severe oxygen desaturation). Of 7708 intubations, 1474 (22%) required ≥3 attempts. Patient, provider, and practice factors were associated with higher TI attempts. Increasing intubation attempts was independently associated with a higher risk for TIAE. The adjusted odds ratio for TIAE and severe oxygen desaturation were significantly higher in TIs with 2 and ≥3 attempts than with one attempt. The risk of adverse safety events during intubation increases with the number of intubation attempts.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2018
DOI: 10.1038/S41598-018-30868-X
Abstract: The preterm lung is particularly vulnerable to ventilator-induced lung injury (VILI) as a result of mechanical ventilation. However the developmental and pathological cellular mechanisms influencing the changing patterns of VILI have not been comprehensively delineated, preventing the advancement of targeted lung protective therapies. This study aimed to use SWATH-MS to comprehensively map the plasma proteome alterations associated with the initiation of VILI following 60 minutes of standardized mechanical ventilation from birth in three distinctly different developmental lung states the extremely preterm, preterm and term lung using the ventilated lamb model. Across these gestations, 34 proteins were differentially altered in matched plasma s les taken at birth and 60 minutes. Multivariate analysis of the plasma proteomes confirmed a gestation-specific response to mechanical ventilation with 79% of differentially-expressed proteins altered in a single gestation group only. Six cellular and molecular functions and two physiological functions were uniquely enriched in either the extremely preterm or preterm group. Correlation analysis supported gestation-specific protein-function associations within each group. In identifying the gestation-specific proteome and functional responses to ventilation we provide the founding evidence required for the potential development of in idualized respiratory support approaches tailored to both the developmental and pathological state of the lung.
Publisher: Elsevier BV
Date: 12-2003
Publisher: American Physiological Society
Date: 15-11-2015
DOI: 10.1152/AJPLUNG.00277.2015
Abstract: A sustained first inflation (SI) at birth may aid lung liquid clearance and aeration, but the impact of SI duration relative to the volume-response of the lung is poorly understood. We compared three SI strategies: 1) variable duration defined by attaining volume equilibrium using real-time electrical impedance tomography (EIT SI plat ) 2) 30 s beyond equilibrium (SI long ) 3) short 30-s SI (SI 30 ) and 4) positive pressure ventilation without SI (no-SI) on spatiotemporal aeration and ventilation (EIT), gas exchange, lung mechanics, and regional early markers of injury in preterm lambs. Fifty-nine fetal-instrumented lambs were ventilated for 60 min after applying the allocated first inflation strategy. At study completion molecular and histological markers of lung injury were analyzed. The time to SI volume equilibrium, and resultant volume, were highly variable mean (SD) 55 (34) s, coefficient of variability 59%. SI plat and SI long resulted in better lung mechanics, gas exchange and lower ventilator settings than both no-SI and SI 30 . At 60 min, alveolar-arterial difference in oxygen was a mean (95% confidence interval) 130 (13, 249) higher in SI 30 vs. SI long group (two-way ANOVA). These differences were due to better spatiotemporal aeration and tidal ventilation, although all groups showed redistribution of aeration towards the nondependent lung by 60 min. Histological lung injury scores mirrored spatiotemporal change in aeration and were greatest in SI 30 group ( P 0.01, Kruskal-Wallis test). An in idualized volume-response approach to SI was effective in optimizing aeration, homogeneous tidal ventilation, and respiratory outcomes, while an inadequate SI duration had no benefit over positive pressure ventilation alone.
Publisher: Springer Science and Business Media LLC
Date: 27-12-2013
DOI: 10.1038/PR.2013.251
Abstract: The aims of the present study were (i) to characterize the relationship between mean airway pressure (PAW) and reactance measured at 5 Hz (reactance of the respiratory system (X RS), forced oscillation technique) and (ii) to compare optimal PAW (P opt) defined by X RS, oxygenation, lung volume (VL), and tidal volume (VT) in preterm lambs receiving high-frequency oscillatory ventilation (HFOV). Nine 132-d gestation lambs were commenced on HFOV at PAW of 14 cmH2O (P start). PAW was increased stepwise to a maximum pressure (P max) and subsequently sequentially decreased to the closing pressure (Pcl, oxygenation deteriorated) or a minimum of 6 cmH2O, using an oxygenation-based recruitment maneuver. X RS, regional V L (electrical impedance tomography), and V T were measured immediately after (t 0 min) and 2 min after (t 2 min) each PAW decrement. P opt defined by oxygenation, X RS, V L, and V T were determined. The PAW-X RS and PAW-VT relationships were dome shaped with a maximum at Pcl+6 cmH2O, the same point as P opt defined by VL. Below Pcl+6 cmH2O, X RS became unstable between t 0 min and t 2 min and was associated with derecruitment in the dependent lung. P opt, as defined by oxygenation, was lower than the P opt defined by X RS, V L, or V T. X RS has the potential as a bedside tool for optimizing PAW during HFOV.
Publisher: Springer Science and Business Media LLC
Date: 04-2004
DOI: 10.1007/S00431-004-1408-Y
Abstract: Ten neonates with coxsackie B viral infection presented over a 3-month period. Clinical features included meningoencephalitis, thrombocytopenia, disseminated intravascular coagulopathy, cardiomyopathy, and hepatitis. Eight infants had multiorgan disease, four with severe myocardial dysfunction, of whom two died. All of the infants with severe disease developed symptoms within 7 days of age. In infants presenting within 10 days of birth, in all cases there were symptoms compatible with maternal infection prior to delivery. Severity was associated with perinatal transmission. Enteroviral polymerase chain reaction of CSF, urine, stool or throat swab was positive in nine of the ten babies. Seven of the infants were treated with a 7-day course of the new anti-picornaviral drug pleconaril (5 mg/kg 3 times daily). These cases highlight the importance of not missing coxsackie B viral infection in the differential diagnosis of the septic neonate, especially as there is now a potential treatment.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Springer Science and Business Media LLC
Date: 21-09-2010
DOI: 10.1007/S00134-010-2049-4
Abstract: Perfusion in healthy adults is gravity-dependent. Little is known about lung perfusion in the preterm infant. The aim of this study was to describe the regional distribution of blood volume within the thorax in preterm infants receiving synchronised volume-targeted mechanical ventilation (SIPPV + TTV) and to compare this to regional distribution of tidal ventilation using electrical impedance tomography (EIT). Stable supine ventilated preterm infants ( 7 days) and oxygen requirement. A total of 5,471 beats were analysed from 26 infants (78 recordings) mean (standard deviation (SD)) gestational age was 26 (2) weeks and mean (SD) postnatal age was 9 (10) days. The median (interquartile range) ΔZ (c) in the anterior half of the hemithorax was 1.41-fold (0.88-2.11) greater than that in the posterior half. The geometric centre of ΔZ (c) was located at 46.7% of the anterior-posterior thoracic distance, compared to a more centrally located ΔZ (v) (49.6% p < 0.0001). The ΔZ (v)/ΔZ (c) ratio was 1.7 in the anterior third of the chest and 2.2 in the posterior (p 7 days of age and not influenced by oxygen requirement. There are gravity dependent differences in the distribution of blood volume and ventilation in the ventilated preterm chest.
Publisher: Springer Science and Business Media LLC
Date: 10-2009
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.JPEDS.2017.04.046
Abstract: To determine whether applying nasal continuous positive airway pressure (CPAP) using systematic changes in continuous distending pressure (CDP) results in a quasi-static pressure-volume relationship in very preterm infants receiving first intention CPAP in the first 12-18 hours of life. Twenty infants at <32 weeks' gestation with mild respiratory distress syndrome (RDS) managed exclusively with nasal CPAP had CDP increased from 5 to 8 to 10 cmH Overall, there was a relationship between P It was possible to define a pressure-volume relationship of the lung and demonstrate reversal of atelectasis by systematically manipulating CDP in most very preterm infants with mild RDS. This suggests that CDP manipulation can be used to optimize the volume state of the preterm lung.
Publisher: BMJ
Date: 20-12-2010
Publisher: American Thoracic Society
Date: 15-12-2019
Publisher: Cold Spring Harbor Laboratory
Date: 04-03-2022
DOI: 10.1101/2022.03.03.482754
Abstract: The impact of different respiratory strategies at birth on the preterm lung is well understood, however, concerns have been raised that lung recruitment may impede cerebral haemodynamics. This study aims to examine the effect of three different ventilation strategies on cerebral haemodynamics and oxygenation. 124-127 day gestation apnoeic intubated preterm lambs (n=68) being studied as part of a larger program primarily assessing lung injury were randomised to positive pressure ventilation with positive end-expiratory pressure (PEEP) 8 cmH 2 O (No-RM n=12), sustained inflation (SI n=15) or dynamic PEEP strategy (DynPEEP maximum PEEP 14 or 20 cmH 2 O, n=41) at birth, followed by 90 minutes of standardised ventilation. Haemodynamic data was continuously recorded, with intermittent arterial blood gas analysis. Main outcome measures for this study included carotid blood flow, carotid artery oxygen content and carotid oxygen delivery. Overall carotid blood flow measures were comparable between strategies, with the exception of mean carotid blood flow which was significantly lower for the SI group compared to the No-RM and DynPEEP groups respectively over the first 3 minutes (p .0001, mixed-effects model). Carotid oxygen content and oxygen delivery were similar between strategies. Maximum PEEP did not alter cerebral haemodynamic measures. Although there were some short-term variations in cerebral haemodynamics between different PEEP strategies and SI, these were not sustained. Different pressure strategies to facilitate lung aeration at birth in preterm infants have been proposed. There is minimal information on the effect of lung recruitment on cerebral haemodynamics. This is the first study that compares the effect of sustained lung inflation, and dynamic and static positive end-expiratory pressure on cerebral haemodynamics. We found that the different ventilation strategies did not alter carotid blood flow, carotid oxygen content or carotid oxygen delivery. This preclinical study provides some reassurance that respiratory strategies designed to focus on lung aeration at birth may not impact cerebral haemodynamics in preterm neonates.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2020
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.JPEDS.2010.08.044
Abstract: To evaluate whether lung lavage with surfactant changes the duration of mechanical respiratory support or other outcomes in meconium aspiration syndrome (MAS). We conducted a randomized controlled trial that enrolled ventilated infants with MAS. Infants randomized to lavage received two 15-mL/kg aliquots of dilute bovine surfactant instilled into, and recovered from, the lung. Control subjects received standard care, which in both groups included high frequency ventilation, nitric oxide, and, where available, extracorporeal membrane oxygenation (ECMO). Sixty-six infants were randomized, with one ineligible infant excluded from analysis. Median duration of respiratory support was similar in infants who underwent lavage and control subjects (5.5 versus 6.0 days, P = .77). Requirement for high frequency ventilation and nitric oxide did not differ between the groups. Fewer infants who underwent lavage died or required ECMO: 10% (3/30) compared with 31% (11/35) in the control group (odds ratio, 0.24 95% confidence interval, 0.060-0.97). Lavage transiently reduced oxygen saturation without substantial heart rate or blood pressure alterations. Mean airway pressure was more rapidly weaned in the lavage group after randomization. Lung lavage with dilute surfactant does not alter duration of respiratory support, but may reduce mortality, especially in units not offering ECMO.
Publisher: Elsevier BV
Date: 03-2004
Publisher: American Physiological Society
Date: 03-2020
DOI: 10.1152/AJPLUNG.00302.2019
Abstract: Despite recent insights into the dynamic processes during lung aeration at birth, several aspects remain poorly understood. We aimed to characterize changes in lung mechanics during the first inflation at birth and their relationship to changes in lung volume. Intubated preterm lambs (gestational age, 124–127 days n = 17) were studied at birth. Lung volume changes were measured by electrical impedance tomography (V L EIT ). Respiratory system resistance (R 5 ) and oscillatory compliance (C x5 ) were monitored with the forced oscillation technique at 5 Hz. Lambs received 3–7 s of 8 cmH 2 O of continuous distending pressure (CDP) before delivery of a sustained inflation (SI) of 40 cmH 2 O. The SI was then applied until either C x5 or the V L EIT or the airway opening volume was stable. CDP was resumed for 3–7 s before commencement of mechanical ventilation. The exponential increases with time of C x5 and V L EIT from commencement of the SI were characterized by estimating their time constants (τC x5 and τV L EIT , respectively). During SI, a fast decrease in R 5 and an exponential increase in C x5 and V L EIT were observed. C x5 and V L EIT provided comparable information on the dynamics of lung aeration in all lambs, with τC x5 and τV L EIT being highly linearly correlated ( r 2 = 0.87, P 0.001). C x5 and V L EIT decreased immediately after SI. Despite the standardization of the animal model, changes in C x5 and R 5 both during and after SI were highly variable. Lung aeration at birth is characterized by a fast reduction in resistance and a slower increase in oscillatory compliance, the latter being a direct reflection of the amount of lung aeration.
Publisher: Springer Berlin Heidelberg
Date: 08-04-2014
Publisher: S. Karger AG
Date: 2021
DOI: 10.1159/000513783
Abstract: Continuous positive airway pressure and surfactant represent the first- and second-line treatment for respiratory distress syndrome in preterm neonates, as European and American guidelines, since 2013 and 2014, respectively, started to recommend surfactant replacement only when continuous positive airway pressure fails. These recommendations, however, are not personalized to the in idual physiopathology. Simple clinical algorithms may have improved the diffusion of neonatal care, but complex medical issues can hardly be addressed with simple solutions. The treatment of respiratory distress syndrome is a complex matter and can be only optimized with personalization. We performed a review of tools to in idualize the management of respiratory distress syndrome based on physiopathology and actual patients’ need, according to precision medicine principles. Advanced oxygenation metrics, lung ultrasound, electrical impedance tomography, and both quantitative and qualitative surfactant assays were examined. When these techniques were investigated with diagnostic accuracy studies, reliability measures have been meta-analysed. Amongst all these tools, quantitative lung ultrasound seems the more developed for the widespread use and has a higher diagnostic accuracy (meta-analytical AUC = 0.952 [95% CI: 0.951–0.953]). Surfactant adsorption (AUC = 0.840 [95% CI: 0.824–0.856]) and stable microbubble test (AUC = 0.800 [95% CI: 0.788–0.812]) also have good reliability, but need further industrial development. We advocate for a more accurate characterization and a personalized approach of respiratory distress syndrome. With the above-described currently available tools, it should be possible to personalize the treatment of respiratory distress syndrome according to physiopathology.
Publisher: Springer Berlin Heidelberg
Date: 08-04-2014
Publisher: Wiley
Date: 30-01-2012
DOI: 10.1002/PPUL.21607
Abstract: High-frequency jet ventilation (HFJV) is often used to treat infants with pathologies associated with gas trapping and abnormal lung mechanics, who are sensitive to the adverse effects of suction. This study aimed to investigate the effect of closed suction (CS), catheter size, and the use of active post-suction sighs on tracheal pressure (P(trach)), and global and regional end-expiratory lung volume (EELV) during HFJV. Six anaesthetized and muscle-relaxed adult rabbits were stabilized on HFJV. CS was performed using all permutations of three CS methods (Continual negative pressure, negative pressure applied during Withdrawal, and HFJV in Standby) and 6 French gauge (6 FG) and 8 French gauge (8 FG) catheter, randomly assigned. The sequence was repeated using post-suction sighs. P(trach), absolute (respiratory inductive plethysmography) and regional (electrical impedance tomography expressed as percentage of vital capacity for the defined region of interest, %Z(VCroi) ) EELV were measured before, during and 60 sec post-suction. CS methods exerted no difference on ΔP(trach), ΔEELV(RIP), or Δ%Z(VCroi) . 8FG catheter resulted in a mean (95%CI) 20.0 (17.9,22.2) cm H(2)O greater loss of P(trach) during suction compared to 6FG (Bonferroni post-test). Mean (± SD) ΔEELV(RIP) was -6(±3) and -2(±1) ml/kg with the 8 and 6 FG catheters (P < 0.0001 Bonferroni post-test). ΔEELV was 31.7 (21.1,42.4) %Z(VCroi) and 24.8 (10.9,38.7) %Z(VCroi) greater in the ventral and dorsal hemithoraces using the 8 FG. Only after 8 FG CS was post-suction recruitment required to restore EELV. In this animal model receiving HFJV, ΔP(trach), ΔEELV, and need for post-suction recruitment during CS were most influenced by catheter size. Volume changes within the lung were uniform.
Publisher: Springer Berlin Heidelberg
Date: 10-04-2015
Publisher: American Thoracic Society
Date: 11-2019
Publisher: BMJ
Date: 23-06-2021
DOI: 10.1136/ARCHDISCHILD-2021-321788
Abstract: To evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (V T ) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support. Prospective observational study. Single-centre tertiary neonatal intensive care unit. Preterm infants born weeks’ gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion. EIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians. Global and regional ΔEELV and ΔV T , heart rate, respiratory rate and oxygen saturation were measured throughout. Thirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cm H 2 O. SpO 2 /FiO 2 ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). V T was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned V T to pre-extubation patterns. EIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.
Publisher: Springer Science and Business Media LLC
Date: 08-03-2016
DOI: 10.1038/PR.2016.39
Abstract: Aerosolization of exogenous surfactant remains a challenge. This study is aimed to evaluate the efficacy of atomized poractant alfa (Curosurf) administered with a novel atomizer in preterm lambs with respiratory distress syndrome. Twenty anaesthetized lambs, 127 ± 1 d gestational age, (mean ± SD) were instrumented before birth and randomized to receive either (i) positive pressure ventilation without surfactant (Control group), (ii) 200 mg/kg of bolus instilled surfactant (Bolus group) at 10 min of life or (iii) 200 mg/kg of atomized surfactant (Atomizer group) over 60 min from 10 min of life. All lambs were ventilated for 180 min with a standardized protocol. Lung mechanics, regional lung compliance (electrical impedance tomography), and carotid blood flow (CBF) were measured with arterial blood gas analysis. Dynamic compliance and oxygenation responses were similar in the Bolus and Atomizer groups, and both better than Control by 180 min (all P < 0.05 two-way ANOVA). Both surfactant groups demonstrated more homogeneous regional lung compliance throughout the study period. There were no differences in CBFConclusion:In a preterm lamb model, atomized surfactant resulted in similar gas exchange and mechanics as bolus administration. This study suggests evaluation of supraglottic atomization with this system when noninvasive support is warranted.
Publisher: BMJ
Date: 31-01-2022
DOI: 10.1136/ARCHDISCHILD-2021-322990
Abstract: Non-invasive high-frequency oscillatory ventilation (nHFOV) is an extension of nasal continuous positive airway pressure (nCPAP) support in neonates. We aimed to compare global and regional distribution of lung volumes during nHFOV versus nCPAP. In 30 preterm infants enrolled in a randomised crossover trial comparing nHFOV with nCPAP, electrical impedance tomography data were recorded in prone position. For each mode of respiratory support, four episodes of artefact-free tidal ventilation, each comprising 30 consecutive breaths, were extracted. Tidal volumes (V T ) in 36 horizontal slices, indicators of ventilation homogeneity and end-expiratory lung impedance (EELI) for the whole lung and for four horizontal regions of interest (non-gravity-dependent to gravity-dependent EELI NGD , EELI midNGD , EELI midGD , EELI GD ) were compared between nHFOV and nCPAP. Aeration homogeneity ratio (AHR) was determined by iding aeration in non-gravity-dependent parts of the lung through gravity-dependent regions. Overall, 228 recordings were analysed. Relative V T was greater in all but the six most gravity-dependent lung slices during nCPAP (all p .05). Indicators of ventilation homogeneity were similar between nHFOV and nCPAP (all p .05). Aeration was increased during nHFOV (mean difference (95% CI)=0.4 (0.2 to 0.6) arbitrary units per kilogram (AU/kg), p=0.013), mainly due to an increase in non-gravity-dependent regions of the lung (∆EELI NGD =6.9 (0.0 to 13.8) AU/kg, p=0.028 ∆EELI midNGD =6.8 (1.2 to 12.4) AU/kg, p=0.009). Aeration was more homogeneous during nHFOV compared with nCPAP (mean difference (95% CI) in AHR=0.01 (0.00 to 0.02), p=0.0014). Although regional ventilation was similar between nHFOV and nCPAP, end-expiratory lung volume was higher and aeration homogeneity was slightly improved during nHFOV. The aeration difference was greatest in non-gravity dependent regions, possibly due to the oscillatory pressure waveform. The clinical importance of these findings is still unclear.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2013
Publisher: Cold Spring Harbor Laboratory
Date: 05-02-2021
DOI: 10.1101/2021.02.03.21251050
Abstract: To evaluate the feasibility of EIT to describe the regional tidal ventilation (V T ) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support. Prospective observational study Single-centre tertiary neonatal intensive care unit Preterm infants born weeks gestation who were being extubated to nasal continuous positive airway pressure (nCPAP) as per clinician discretion. Electrical Impedance Tomography measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 minutes after commencing nCPAP. Extubation and pressure settings were determined by clinicians. Global and regional ΔEELV and ΔV T were measured. Heart rate, respiratory rate and oxygen saturation were measured throughout. Thirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cmH 2 O. SpO 2 /FiO 2 ratio was mean (95% CI) 50 (35, 65) lower 20 minutes after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared to SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). V T was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned V T to pre-extubation patterns. Lung behaviour during the transition from invasive positive pressure ventilation to CPAP at moderate distending pressures is variable and associated with lung volume loss in the ventral lung.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2015
DOI: 10.1161/CIRCGENETICS.115.001225
Abstract: Smoking is an important cardiovascular disease risk factor, but the mechanisms linking smoking to blood pressure are poorly understood. Data on 141 317 participants (62 666 never, 40 669 former, 37 982 current smokers) from 23 population-based studies were included in observational and Mendelian randomization meta-analyses of the associations of smoking status and smoking heaviness with systolic and diastolic blood pressure, hypertension, and resting heart rate. For the Mendelian randomization analyses, a genetic variant rs16969968/rs1051730 was used as a proxy for smoking heaviness in current smokers. In observational analyses, current as compared with never smoking was associated with lower systolic blood pressure and diastolic blood pressure and lower hypertension risk, but with higher resting heart rate. In observational analyses among current smokers, 1 cigarette/day higher level of smoking heaviness was associated with higher (0.21 bpm 95% confidence interval 0.19 0.24) resting heart rate and slightly higher diastolic blood pressure (0.05 mm Hg 95% confidence interval 0.02 0.08) and systolic blood pressure (0.08 mm Hg 95% confidence interval 0.03 0.13). However, in Mendelian randomization analyses among current smokers, although each smoking increasing allele of rs16969968/rs1051730 was associated with higher resting heart rate (0.36 bpm/allele 95% confidence interval 0.18 0.54), there was no strong association with diastolic blood pressure, systolic blood pressure, or hypertension. This would suggest a 7 bpm higher heart rate in those who smoke 20 cigarettes/day. This Mendelian randomization meta-analysis supports a causal association of smoking heaviness with higher level of resting heart rate, but not with blood pressure. These findings suggest that part of the cardiovascular risk of smoking may operate through increasing resting heart rate.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2014
Publisher: American Physiological Society
Date: 11-2023
Publisher: IOP Publishing
Date: 17-04-2020
Publisher: Cold Spring Harbor Laboratory
Date: 02-2021
DOI: 10.1101/2021.01.28.21250723
Abstract: Clinicians have little guidance on the time needed before assessing the effect of a mean airway pressure (P AW ) change during high-frequency oscillatory ventilation (HFOV). We aimed to determine 1) time to stable lung volume after a P AW change during HFOV and, 2) the relationship between time to volume stability and the volume state of the lung. Continuous lung volume measurements (respiratory inductive plethysmography) after 1-2 cmH 2 O P AW changes made every 10 minutes during an open lung strategy (n=13 infants) were analysed with a bi-exponential model. Time to stable lung volume (extrapolated to maximum 3600s) was calculated if the model R 2 was .6. 196 P AW changes were made, with no volume change in 33 (17%) occurrences. 125 volume signals met modelling criteria for inclusion median (IQR) R 2 0.96 (0.91, 0.98). The time to stable lung volume was 1131 (718, 1959)s (P AW increases) and 647 (439, 1309)s (P AW decreases), with only 17 (14%) occurring within 10 minutes and time to stability being longer when the lung was atelectatic. During HFOV, the time to stable lung volume after a P AW change is variable, often requires more than 10 minutes and is dependent on the preceding volume state. In infants without preterm respiratory distress syndrome the time to achieve lung volume stability after a P AW change during HFOV is usually greater than 10 minutes. The volume state of the lung at the time of P AW change influences the time required to achieve a stable new lung volume being shorter when the lung is well recruited and longer when the lung is already atelectatic. Clinicians should be aware that it may require least 10 minutes before assessing the clinical response to a change in P AW during HFOV
Publisher: BMJ
Date: 19-09-2023
Publisher: BMJ
Date: 02-11-2016
DOI: 10.1136/ARCHDISCHILD-2015-309611
Abstract: A sustained inflation has been advocated as a potential method of augmenting lung aeration at birth. Clinical trials have suggested that a sustained inflation may lead to a reduced need for intubation and ventilation in the first few days of life, without cardiovascular compromise or increased lung injury. Despite this, a sustained inflation is not currently a standard of practice, mainly due to a lack of clarity regarding the optimal delivery method. Animal trials have sought to refine delivery techniques. This review will outline current recommendations regarding a sustained inflation, discuss potential strategies for its optimal delivery and suggest priorities for future research.
Publisher: BMJ
Date: 11-2019
DOI: 10.1136/BMJOPEN-2019-032122
Abstract: Congenital diaphragmatic hernia (CDH) is a developmental defect of the diaphragm that impairs normal lung development, causing pulmonary hypertension (PH). PH in CDH newborns is the main determinant for morbidity and mortality. Different therapies are still mainly based on ‘trial and error’. Inhaled nitric oxide (iNO) is often the drug of first choice. However, iNO does not seem to improve mortality. Intravenous sildenafil has reduced mortality in newborns with PH without CDH, but prospective data in CDH patients are lacking. In an open label, multicentre, international randomised controlled trial in Europe, Canada and Australia, 330 newborns with CDH and PH are recruited over a 4-year period (2018–2022). Patients are randomised for intravenous sildenafil or iNO. Sildenafil is given in a loading dose of 0.4 mg/kg in 3 hours followed by continuous infusion of 1.6 mg/kg/day, iNO is dosed at 20 ppm. Primary outcome is absence of PH on day 14 without pulmonary vasodilator therapy and/or absence of death within the first 28 days of life. Secondary outcome measures include clinical and echocardiographic markers of PH in the first year of life. We hypothesise that sildenafil gives a 25% reduction in the primary outcome from 68% to 48% on day 14, for which a s le size of 330 patients is needed. An intention-to-treat analysis will be performed. A p-value (two-sided) .05 is considered significant in all analyses. Ethics approval has been granted by the ethics committee in Rotterdam (MEC-2017-324) and the central Committee on Research Involving Human Subjects (NL60229.078.17) in the Netherlands. The principles of the Declaration of Helsinki, the Medical Research Involving Human Subjects Act and the national rules and regulations on personal data protection will be used. Parental informed consent will be obtained. NTR6982 Pre-results.
Publisher: Informa UK Limited
Date: 21-02-2022
DOI: 10.1080/10408363.2022.2038074
Abstract: Neonatal jaundice is one of the most common clinical conditions affecting newborns. For most newborns, jaundice is harmless, however, a proportion of newborns develops severe neonatal jaundice requiring therapeutic interventions, accentuating the need to have reliable and accurate screening tools for timely recognition across different health settings. The gold standard method in diagnosing jaundice involves a blood test and requires specialized hospital-based laboratory instruments. Despite technological advancements in point-of-care laboratory medicine, there is limited accessibility of the specialized devices and s le stability in geographically remote areas. Lack of suitable testing options leads to delays in timely diagnosis and treatment of clinically significant jaundice in developed and developing countries alike. There has been an ever-increasing need for a low-cost, simple to use screening technology to improve timely diagnosis and management of neonatal jaundice. Consequently, several point-of-care (POC) devices have been developed to address this concern. This paper aims to review the literature, focusing on emerging technologies in the screening and diagnosing of neonatal jaundice. We report on the challenges associated with the existing screening tools, followed by an overview of emerging sensors currently in pre-clinical development and the emerging POC devices in clinical trials to advance the screening of neonatal jaundice. The benefits offered by emerging POC devices include their ease of use, low cost, and the accessibility of rapid response test results. However, further clinical trials are required to overcome the current limitations of the emerging POC's before their implementation in clinical settings. Hence, the need for a simple to use, low-cost POC jaundice detection technology for newborns remains an unsolved challenge globally.
Publisher: American Thoracic Society
Date: 07-2016
Publisher: American Thoracic Society
Date: 15-07-2018
Publisher: European Respiratory Society (ERS)
Date: 14-03-2018
DOI: 10.1183/16000617.0108-2017
Abstract: Chronic respiratory morbidity is a common complication of premature birth, generally defined by the presence of bronchopulmonary dysplasia, both clinically and in trials of respiratory therapies. However, recent data have highlighted that bronchopulmonary dysplasia does not correlate with chronic respiratory morbidity in older children born preterm. Longitudinally evaluating pulmonary morbidity from early life through to childhood provides a more rational method of defining the continuum of chronic respiratory morbidity of prematurity, and offers new insights into the efficacy of neonatal respiratory interventions. The changing nature of preterm lung disease suggests that a multimodal approach using dynamic lung function assessment will be needed to assess the efficacy of a neonatal respiratory therapy and predict the long-term respiratory consequences of premature birth. Our aim is to review the literature regarding the long-term respiratory outcomes of neonatal respiratory strategies, the difficulties of assessing dynamic lung function in infants, and potential new solutions.
Publisher: Wiley
Date: 22-11-2012
DOI: 10.1111/J.1440-1754.2011.02227.X
Abstract: Universal vaccination with an oral live-attenuated rotavirus vaccine at 2, 4 and 6 months of age was introduced in Australia in July 2007. There are no data on the short-term effects of vaccination for those infants most at risk of severe complications from rotavirus infection. The aim of this study was to describe the effects of rotavirus vaccination on weight gain and gastrointestinal losses in infants with functional short gut syndrome secondary to an ileostomy. A retrospective review of all infants with an ileostomy who received RotaTeq while hospitalised at the Royal Children's Hospital, Melbourne from July 2007 to July 2009 was performed. Daily data were collected from 1 week before to 2 weeks after vaccination. The data included type and volume of feeds, ileostomy losses, need for fluid replacement of ileostomy losses, weight, temperature, urine sodium, stool culture, suspected and confirmed sepsis. Nine infants (age at first RotaTeq 61-99 days) were identified. The median (range) gestational age was 26 (24, 38) completed weeks and birthweight was 737 (620, 2714) grams. Compared to the day of vaccination, the median (range) ileostomy losses 1 week before, 1 and 2 weeks after vaccination were -1.1 (-13.6, 4.9) mL/kg/day, 2 (-11.1, 25.0) mL/kg/day and 2.4 (-15.7, 27.2) mL/kg/day, respectively. One infant developed severe stomal losses after vaccination. Overall, rotavirus vaccination did not alter weight gain, temperature or urinary sodium. In this small series, oral live-attenuated rotavirus vaccination of infants with high-output ileostomy was tolerated in most cases.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JPEDS.2017.01.074
Abstract: To describe expiratory tidal volume (V A total of 26 neonates needing surgery under general anesthesia were studied, of whom 18 were intubated postoperatively. V A total of 2597 V V
Publisher: Wiley
Date: 30-11-2013
DOI: 10.1111/APA.12070
Abstract: Lung lavage using two aliquots of 15 mL/kg of dilute surfactant was performed in 30 ventilated infants with severe meconium aspiration syndrome (MAS). Mean recovery of instilled lavage fluid was 46%, with greater fluid return associated with lower mean airway pressure at 24 h and a shorter duration of respiratory support. Recovery of instilled lavage fluid is paramount in effective lung lavage in MAS and must be afforded priority in the lavage technique.
Publisher: BMJ
Date: 11-08-2013
DOI: 10.1136/FETALNEONATAL-2011-301606
Abstract: To compare the agreement, precision and repeatability of end tidal carbon dioxide (EtCO2 ) and transcutaneous carbon dioxide (TcCO2 ) with partial pressure of arterial CO(2) ( PaCO2) in postoperative neonates. Fifty mechanically ventilated neonates without lung disease, and with no contraindications for either TcCO2 or EtCO2 monitoring. Paired TcCO2 and EtCO2 values were recorded with three consecutive measurements within the first 48 h of surgery. EtCO2, TcCO2 and PaCO2 triplets were compared using Bland-Altman plots. One hundred thirty-two triplet measures of CO(2) were recorded with mean PaCO2 43.5 (7.3) mm Hg, EtCO2 38.8 (6.4) mm Hg and 43.8 (8.8) mm Hg (p<0.0001 for EtCO2 against PaCO2 paired t test). The PaCO2 - EtCO2 bias±2SD was 4.1±9.0 mm Hg and -0.8±13.0 mm Hg for PaCO2 - TcCO2. 56.1% of EtCO2, and 60.6% of TcCO2 values were within ±5 mm Hg of paired PaCO2. In postoperative neonates, EtCO2 and TcCO2 demonstrated a clinically acceptable agreement with PaCO2.
Publisher: Wiley
Date: 13-01-2018
DOI: 10.1111/JPC.13824
Abstract: Maintaining normothermia is a tenet of neonatal care. However, neonatal thermal care guidelines applicable to intra-hospital transport beyond the neonatal intensive care unit (NICU) and during surgery or magnetic resonance imaging (MRI) are lacking. The aim of this study is to determine the proportion of infants normothermic (36.5-37.5°C) on return to NICU after management during surgery and MRI, and during standard clinical care in both environments. Sixty-two newborns requiring either surgery in the operating theatre (OT) (n = 41) or an MRI scan (n = 21) at the Royal Children's Hospital (Melbourne) NICU were prospectively studied. Core temperature, along with cardiorespiratory parameters, was continuously measured from 15 min prior to leaving the NICU until 60 min after returning. Passive and active warming (intra-operatively) was at clinician discretion. The study reported 90% of infants were normothermic before leaving NICU: 86% (MRI) and 93% (OT). Only 52% of infants were normothermic on return to NICU (relative risk (RR) 1.75 95% confidence interval (CI) 1.39-2.31 number needed to harm (NNH) 2.6). Between departure from the NICU and commencement of surgery, core temperature decreased by mean 0.81°C (95% CI 0.30-1.33 P = 0.0001, analysis of variance), with only 24% of infants normothermic when surgery began (P < 0.0001 RR 3.80 (95% CI 2.33-6.74) NNH 1.5). After an MRI, infants were a mean 0.41°C (95% CI 0.16-0.67) colder than immediately before entering the scanner (P = 0.001, analysis of variance), with only 43% being normothermic (P = 0.003 RR 2.11 (95% CI 1.35-3.74) NNH 2.1). Unintentional hypothermia is a common occurrence during surgery in the OT and MRI in neonates, indicating that evidence-based warming strategies to prevent hypothermia should be developed.
Publisher: S. Karger AG
Date: 2015
DOI: 10.1159/000431216
Abstract: b i Background: /i /b The mode of waveform generation and circuit characteristics differ between high-frequency oscillators. It is unknown if this influences performance. b i Objectives: /i /b To describe the relationships between set and delivered pressure litude (& #x0394 P), and the interaction with frequency and endotracheal tube (ETT) diameter, in eight high-frequency oscillators. b i Methods: /i /b Oscillators were evaluated using a 70-ml test lung at 1.0 and 2.0 ml/cm H sub /sub O compliance, with mean airway pressures (P sub AW /sub ) of 10 and 20 cm H sub /sub O, frequencies of 5, 10 and 15 Hz, and an ETT diameter of 2.5 and 3.5 mm. At each permutation of P sub AW /sub , frequency and ETT, the set & #x0394 P was sequentially increased from 15 to 50 cm H sub /sub O, or from 20 to 100% maximum litude (10% increments) depending on the oscillator design. The & #x0394 P at the ventilator (& #x0394 P sub VENT /sub ), airway opening (& #x0394 P sub AO /sub ) and within the test lung (& #x0394 P sub TRACH /sub ), and tidal volume (V sub T /sub ) at the airway opening were determined at each set & #x0394 P. b i Results: /i /b In two oscillators the relationships between set and delivered & #x0394 P were non-linear, with a plateau in & #x0394 P thresholds noted at all frequencies (Dräger Babylog 8000) or ≥10 Hz (Dräger VN500). In all other devices there was a linear relationship between & #x0394 P sub VENT /sub , & #x0394 P sub AO /sub and & #x0394 P sub TRACH /sub (all r sup /sup .93), with differing attenuation of the pressure wave. Delivered V sub T /sub at the different settings tested varied between devices, with some unable to deliver V sub T /sub ml at 15 Hz, and others generating V sub T /sub ml at 5 Hz and a 1:1 inspiratory-to-expiratory time ratio. b i Conclusions: /i /b Clinicians should be aware that modern high-frequency oscillators exhibit important differences in the delivered & #x0394 P and V sub T /sub .
Publisher: Springer Science and Business Media LLC
Date: 10-2009
Publisher: Cold Spring Harbor Laboratory
Date: 06-08-2020
DOI: 10.1101/2020.08.04.20168575
Abstract: To determine the regional ventilation characteristics during non-invasive ventilation in stable preterm infants. The secondary aims were to explore the relationship between indicators of ventilation homogeneity and other clinical measures of respiratory status. Prospective observational study. Two tertiary neonatal intensive care units. Forty stable preterm infants born weeks gestation receiving either CPAP (n=32) or nHF(n=8) if weeks corrected gestation, and extubated for at least 24 hours at time of study. Continuous electrical impedance tomography imaging of regional ventilation during 60-minutes of quiet breathing on clinician-determined non-invasive settings. Gravity-dependent and right-left centre of ventilation (CoV), percentage of whole lung tidal volume by lung region, and percentage of lung unventilated were determined for 120 artefact-free breaths/infant (4770 breaths included). Oxygen saturation, heart and respiratory rates were also measured. Ventilation was greater in the right lung (mean (SD) CoV RL 69.1 (14.9)%) and the gravity non-dependent lung ideal-actual CoV 1.4 (4.5). The central third of the lung received the most tidal volume, followed by the non-dependent and dependent regions (p .0001 repeated measure ANOVA). Ventilation inhomogeneity was associated with worse SpO 2 /FiO 2 , (p=0.031, r 2 0.12 linear regression). In those infants that later developed bronchopulmonary dysplasia (n=25) SpO 2 /FiO 2 was worse and non-dependent ventilation inhomogeneity greater than in those that did not (both p .05 t test Welch correction). There is high breath-by-breath variability in regional ventilation patterns during NIV in preterm infants. Ventilation favoured the gravity non-dependent lung, with ventilation inhomogeneity associated with worse oxygenation.
Publisher: Springer Science and Business Media LLC
Date: 28-02-2007
DOI: 10.1007/S00134-007-0541-2
Abstract: To describe the pattern and magnitude of lung volume change during open endotracheal tube (ETT) suction in infants receiving high-frequency oscillatory ventilation (HFOV). Prospective observational clinical study. Tertiary neonatal intensive care unit. Seven intubated and muscle-relaxed newborn infants receiving HFOV. Open ETT suction was performed for 6 s at -100 mmHg using a 6-F catheter passed to the ETT tip after disconnection from HFOV. The HFOV was then recommenced at the same settings as prior to ETT suction. Change in lung volume (DeltaV (L)) referenced to baseline lung volume before suction was measured with a calibrated respiratory inductive plethysmography recording from 30 s before until 60 s after ETT suction. In all infants ETT suction resulted in significant loss of lung volume. The mean DeltaV (L) during suctioning was -13 ml/kg (SD 4 ml/kg) (p 0.05, Tukey post-test). Open ETT suction caused a significant but transient loss of lung volume in muscle-relaxed newborn infants receiving HFOV.
Publisher: S. Karger AG
Date: 2013
DOI: 10.1159/000353363
Abstract: b i Background: /i /b Very preterm infants can be treated with nasal continuous positive airway pressure (CPAP) from birth, but some fail. A rapid test, such as the stable microbubble test (SMT) on gastric aspirate, may identify those who can be managed successfully using CPAP. b i Objective: /i /b To determine if SMT can identify soon after birth, very preterm infants who may be successfully managed on CPAP alone. b i Methods: /i /b Stable microbubbles (diameter µm) were counted in gastric aspirates taken h of age from infants weeks' gestation, who received CPAP from birth. Infants failed CPAP if intubated at h of age. Clinicians were masked to SMT results. A receiver operating characteristic curve was generated to determine the relationship between number of microbubbles/mm sup /sup and subsequent intubation. b i Results: /i /b 68 infants of mean (SD) 28.1 (1.4) weeks' gestation received CPAP in the delivery room at a median (interquartile range) pressure 7 (6-8) cmH sub /sub O and FiO sub /sub 0.25 (0.21-0.3). Gastric aspirates were taken at a median (interquartile range) age of 0.5 (0.3-0.6) hours. The best cut-off point for predicting CPAP success or failure was a SMT count of 8 microbubbles/mm sup /sup . The area under the receiver operating characteristic curve was 0.8 (95% CI 0.7-0.9). A SMT count ≥8 microbubbles/mm sup /sup had a sensitivity of 53%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 60% for predicting CPAP success. b i Conclusion: /i /b Infants treated with CPAP from birth, who had b /b SMT counts ≥8 microbubbles/mm sup /sup on their gastric aspirate, did not fail CPAP.
Publisher: BMJ
Date: 07-06-2005
Publisher: Springer Science and Business Media LLC
Date: 23-05-2016
DOI: 10.1038/SREP26476
Abstract: Preterm newborns often require invasive support, however even brief periods of supported ventilation applied inappropriately to the lung can cause injury. Real-time quantitative reverse transcriptase-PCR (qPCR) has been extensively employed in studies of ventilation-induced lung injury with the reference gene 18S ribosomal RNA (18S RNA) most commonly employed as the internal control reference gene. Whilst the results of these studies depend on the stability of the reference gene employed, the use of 18S RNA has not been validated. In this study the expression profile of five candidate reference genes (18S RNA, ACTB, GAPDH, TOP1 and RPS29) in two geographical locations, was evaluated by dedicated algorithms, including geNorm, Normfinder, Bestkeeper and ΔCt method and the overall stability of these candidate genes determined (RefFinder). Secondary studies examined the influence of reference gene choice on the relative expression of two well-validated lung injury markers EGR1 and IL1B. In the setting of the preterm lamb model of lung injury, RPS29 reference gene expression was influenced by tissue location however we determined that in idual ventilation strategies influence reference gene stability. Whilst 18S RNA is the most commonly employed reference gene in preterm lamb lung studies, our results suggest that GAPDH is a more suitable candidate.
Publisher: American Physiological Society
Date: 05-2019
Publisher: American Thoracic Society
Date: 02-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2017
DOI: 10.1097/PCC.0000000000001267
Abstract: To determine the short-term tolerance, efficacy, and lung deposition of supraglottic atomized surfactant in spontaneously breathing lambs receiving continuous positive airway pressure. Prospective, randomized animal study. Animal research laboratory. Twenty-two preterm lambs on continuous positive airway pressure (132 ± 1 d gestational age). Animals receiving continuous positive airway pressure via binasal prongs at 8 cm H 2 O were randomized to receive atomized surfactant at approximately 60-minute of life (atom n = 15) or not (control n = 7). The atom group received 200 mg/kg of poractant alfa (Curosurf Chiesi Farmaceutici SpA, Parma, Italy) over 45 minutes via a novel atomizer located in the upper pharynx that synchronized surfactant delivery with the inspiratory phase. Arterial blood gas, regional distribution of tidal ventilation (electrical impedance tomography), and carotid blood flow were recorded every 15 minutes until 90 minutes after stabilizing on continuous positive airway pressure. Gas exchange, respiratory rate, and hemodynamic variables, including carotid blood flow, remained stable during surfactant treatment. There was a significant improvement in arterial alveolar ratio after surfactant delivery in the atom group ( p 0.05 Sidak posttests), while there was no difference in Pa co 2 . Electrical impedance tomography data showed a more uniform pattern of ventilation in the atom group. In the atom group, the median (interquartile range) deposition of surfactant in the lung was 32% (22–43%) of the delivered dose, with an even distribution between the right and the left lungs. In our model of spontaneously breathing lambs receiving CPAP, supraglottic atomization of Curosurf via a novel device was safe, improved oxygenation and ventilation homogeneity compared with CPAP only, and provided a relatively large lung deposition suggesting clinical utility.
Publisher: S. Karger AG
Date: 24-08-2010
DOI: 10.1159/000316854
Abstract: i Background: /i Closed endotracheal suction interferes with mechanical ventilation received by infants, but the change to ventilation may be different when ventilator modes that target expired tidal volume (V i T /i sub e /sub ) are used. i Objective: /i To measure airway pressure and tidal volume distal to the endotracheal tube (ETT) during and after closed suction in a volume-targeted ventilation mode with the Dräger Babylog 8000+, and to determine the time until V i T /i sub e /sub returns to the baseline level. i Methods: /i In this benchtop study, closed suction was performed on 2.5- to 4.0-mm ETTs connected to a test lung. 5–8 French suction catheters were used at suction pressures of 80–200 mm Hg during tidal-volume-targeted ventilation. i Results: /i During catheter insertion and suction, circuit inflating pressure increased and tidal volume was maintained, except when a large catheter relative to the ETT was used, in which case tidal volume decreased. End-expiratory pressure distal to the ETT was reduced during suction by up to 75 cm H sub /sub O while circuit end-expiratory pressure was unchanged. Reduction in end-expiratory pressure distal to the ETT was greatest with large catheters and high suction pressures. Following suction, circuit and tracheal inflating pressures increased and tidal volume increased before returning to baseline in 8–12 s. i Conclusions: /i Closed endotracheal suction interferes with ventilator function in volume-targeted mode, with substantially negative intratracheal pressure during suction, and the potential for high airway pressures and tidal volumes following the procedure. These effects should be considered and pressure limits set appropriately whenever using volume-targeted ventilation.
Publisher: BMJ
Date: 28-06-2018
DOI: 10.1136/ARCHDISCHILD-2017-312640
Abstract: Volume-targeted ventilation (VTV) is widely used and may reduce lung injury, but this assumes the clinically set tidal volume (V Tset ) is accurately delivered. This prospective observational study aimed to determine the relationship between V Tset , expiratory V T (V Te ) and endotracheal tube leak in a modern neonatal volume-targeted ventilator (VTV) and the resultant partial arterial pressure of carbon dioxide (PaCO 2 ) relationship with and without VTV. Continuous inflations were recorded for 24 hours in 100 infants, mean (SD) 34 (4) weeks gestation and 2483 (985) g birth weight, receiving synchronised mechanical ventilation (SLE5000, SLE, UK) with or without VTV and either the manufacturer’s V4 (n=50) or newer V5 (n=50) VTV algorithm. The V Tset , V Te and leak were determined for each inflation (maximum 90 000/infant). If PaCO 2 was s led (maximum of 2 per infant), this was compared with the average V Te data from the preceding 15 min. A total of 7 497 137 inflations were analysed. With VTV enabled (77 infants), the V Tset −V Te bias (95% CI) was 0.03 (−0.12 to 0.19) mL/kg, with a median of 80% of V Te being ±1.0 mL/kg of V Tset . Endotracheal tube leak up to 30% influenced V Tset −V Te bias with the V4 (r 2 =−0.64, p .0001 linear regression) but not V5 algorithm (r 2 =0.04, p=0.21). There was an inverse linear relationship between V Te and PaCO 2 without VTV (r 2 =0.26, p=0.004), but not with VTV (r 2 =0.04, p=0.10), and less PaCO 2 within 40–60 mm Hg, 53% versus 72%, relative risk (95% CI) 1.7 (1.0 to 2.9). VTV was accurate and reliable even with moderate leak and PaCO 2 more stable. VTV algorithm differences may exist in other devices.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2023
DOI: 10.1186/S40635-023-00511-9
Abstract: Mechanical power is a major contributor to lung injury and mortality in adults receiving mechanical ventilation. Recent advances in our understanding of mechanical power have allowed the different mechanical components to be isolated. The preterm lung shares many of the same similarities that would indicate mechanical power may be relevant in this group. To date, the role of mechanical power in neonatal lung injury is unknown. We hypothesise that mechanical power maybe useful in expanding our understanding of preterm lung disease. Specifically, that mechanical power measures may account for gaps in knowledge in how lung injury is initiated. To provide a justification for our hypothesis, data in a repository at the Murdoch Children’s Research Institute, Melbourne (Australia) were re-analysed. 16 preterm lambs 124–127d gestation (term 145d) who received 90 min of standardised positive pressure ventilation from birth via a cuffed endotracheal tube were chosen as each was exposed to three distinct and clinically relevant respiratory states with unique mechanics. These were (1) the respiratory transition to air-breathing from an entirely fluid-filled lung (rapid aeration and fall in resistance) (2) commencement of tidal ventilation in an acutely surfactant-deficient state (low compliance) and (3) exogenous surfactant therapy (improved aeration and compliance). Total, tidal, resistive and elastic-dynamic mechanical power were calculated from the flow, pressure and volume signals (200 Hz) for each inflation. All components of mechanical power behaved as expected for each state. Mechanical power increased during lung aeration from birth to 5 min, before again falling immediately after surfactant therapy. Before surfactant therapy tidal power contributed 70% of total mechanical power, and 53.7% after. The contribution of resistive power was greatest at birth, demonstrating the initial high respiratory system resistance at birth. In our hypothesis-generating dataset, changes in mechanical power were evident during clinically important states for the preterm lung, specifically transition to air-breathing, changes in aeration and surfactant administration. Future preclinical studies using ventilation strategies designed to highlight different types of lung injury, including volu-, baro- and ergotrauma, are needed to test our hypothesis.
Publisher: BMJ
Date: 05-09-2016
Publisher: BMJ
Date: 27-11-2020
DOI: 10.1136/ARCHDISCHILD-2020-320449
Abstract: To determine the regional ventilation characteristics during non-invasive ventilation (NIV) in stable preterm infants. The secondary aim was to explore the relationship between indicators of ventilation homogeneity and other clinical measures of respiratory status. Prospective observational study. Two tertiary neonatal intensive care units. Forty stable preterm infants born weeks of gestation receiving either continuous positive airway pressure (n=32) or high-flow nasal cannulae (n=8) at least 24 hours after extubation at time of study. Continuous electrical impedance tomography imaging of regional ventilation during 60 min of quiet breathing on clinician-determined non-invasive settings. Gravity-dependent and right–left centre of ventilation (CoV), percentage of whole lung tidal volume (V T ) by lung region and percentage of lung unventilated were determined for 120 artefact-free breaths/infant (4770 breaths included). Oxygen saturation, heart and respiratory rates were also measured. Ventilation was greater in the right lung (mean 69.1 (SD 14.9)%) total V T and the gravity-non-dependent (ND) lung ideal–actual CoV 1.4 (4.5)%. The central third of the lung received the most V T , followed by the non-dependent and dependent regions (p .0001 repeated-measure analysis of variance). Ventilation inhomogeneity was associated with worse peripheral capillary oxygen saturation (SpO 2 )/fraction of inspired oxygen (FiO 2 ) (p=0.031, r 2 0.12 linear regression). In those infants that later developed bronchopulmonary dysplasia (n=25), SpO 2 /FiO 2 was worse and non-dependent ventilation inhomogeneity was greater than in those that did not (both p .05, t-test Welch correction). There is high breath-by-breath variability in regional ventilation patterns during NIV in preterm infants. Ventilation favoured the ND lung, with ventilation inhomogeneity associated with worse oxygenation.
Publisher: Elsevier BV
Date: 02-2023
Publisher: American Physiological Society
Date: 04-2015
DOI: 10.1152/JAPPLPHYSIOL.00985.2014
Abstract: Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH 2 O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min ( P = 0.017 two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min ( P 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt.
Publisher: Wiley
Date: 21-05-2013
DOI: 10.1002/PPUL.22580
Abstract: Endotracheal tube (ETT) malposition is common and an increasing number of non-invasive techniques to aid rapid identification of tube position are available. Electrical impedance tomography (EIT) is advocated as a tool to monitor ventilation. This study aimed to compare EIT with five other non-invasive techniques for identifying ETT position in a piglet model. Six saline lavage surfactant-depleted piglets were studied. Periods of ventilation with ETT placed in the oesophagus or a main bronchus (MB) were compared with an appropriately placed mid-tracheal ETT. Colorimetric end-tidal CO(2) (Pedi-Cap®), SpO(2) and heart rate, tidal volume (${\\rm V}_{{\\rm T}_{{\\rm ao}} } $) using a hot-wire anemometer at the airway opening, tidal volume using respiratory inductive plethysmography (${\\rm V}_{{\\rm T}_{{\\rm RIP}} } $) and regional tidal ventilation within each hemithorax (EIT) were measured. Oesophageal ventilation: Pedi-Cap® demonstrated absence of color change. ${\\rm V}_{{\\rm T}_{{\\rm ao}} } $, ${\\rm V}_{{\\rm T}_{{\\rm RIP}} } $, and EIT correctly demonstrated no tidal ventilation. SpO(2) decreased from mean (SD) 96 (2)% to 74 (12)% (P < 0.05 Bonferroni post-test), without heart rate change. MB ventilation: SpO(2) , heart rate and Pedi-Cap® were unchanged compared with mid-tracheal position. ${\\rm V}_{{\\rm T}_{{\\rm ao}} } $ and ${\\rm V}_{{\\rm T}_{{\\rm RIP}} } $ decreased from a mean (SD) 10.8 (5.6) ml/kg and 14.6 (6.2) ml/kg to 5.5 (1.9) ml/kg and 6.4 (2.6) ml/kg (both P < 0.05 Bonferroni post-test). EIT identified the side of MB ventilation, with a mean (SD) 95 (3)% reduction in tidal volume in the unventilated lung. EIT not only correctly identified oesophageal ventilation but also localized the side of MB ventilation. At present, no one technique is without limitations and clinicians should utilize a combination in addition to clinical judgement.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2014
DOI: 10.1038/PR.2013.218
Abstract: Sustained inflation (SI) at birth facilitates establishment of functional residual capacity (FRC) in the preterm lung, but the ideal lung recruitment strategy is unclear. We have compared the effect of SI and a stepwise positive end-expiratory pressure (PEEP SEP) strategy in a preterm model. 127 d gestation lambs received either 20-s SI (n = 9) or 2 cmH2O stepwise PEEP increases to 20 cmH2O every 10 inflations, and then decreases to 6 cmH2O (n = 10). Ventilation continued for 70 min, with surfactant administered at 10 min. Alveolar-arterial oxygen gradient (AaDO2), compliance (C(dyn)), end-expiratory thoracic volume (EEVRIP respiratory inductive plethysmography), and EEV and C(dyn) in the gravity-dependent and nondependent hemithoraces (electrical impedance tomography) were measured throughout. Early mRNA markers of lung injury were analyzed using quantitative real-time PCR. From 15 min of life, AaDO2 was lower in SEP group (P < 0.005 two-way ANOVA). SEP resulted in higher and more homogeneous C(dyn) (P < 0.0001). Mean (SD) EEVRIP at 5 min was 18 (9) ml/kg and 6 (5) ml/kg following SEP and SI, respectively (P = 0.021 Bonferroni posttest) this difference was due to a greater nondependent hemithorax EEV. There was no difference in markers of lung injury. An SEP at birth improved gas exchange, lung mechanics, and EEV, without increasing lung injury, compared to the SI strategy used.
Publisher: Frontiers Media SA
Date: 22-01-2019
Publisher: Springer Science and Business Media LLC
Date: 05-05-2007
DOI: 10.1007/S00134-007-0635-X
Abstract: To compare the effectiveness of open and closed endotracheal suction in recovering thin and thick secretions in normal and injured lungs during conventional and high frequency ventilation. Randomised study in a paediatric intensive care model in the animal research laboratory of a tertiary paediatric hospital. 16 New Zealand White rabbits. Anaesthetised animals were intubated with a 3.5-mm endotracheal tube. Simulated thin and thick secretions (iopamidol 2 ml, a watery radio-opaque fluid, and fluorescent mucin 1 ml) were instilled in turn 1 cm below the tube tip through a catheter placed via a tracheostomy. Open or closed suction, randomly assigned, was applied for 6s at -140 mmHg using a 6-F gauge catheter. Following lung injury with repeated saline lavage the procedure was repeated on conventional and high frequency ventilation. Iopamidol recovery was determined by digitally subtracting the post-contrast and post-suction radiographic images. Mucin recovery was determined by fluorescence assay of the aspirate. In the normal lung similar amounts were recovered by both suction methods. In the lavaged lung closed suction recovered less iopamidol during conventional (22 +/- 7.5%) and high frequency ventilation (11 +/- 2.4%) than open suction (36 +/- 2% and 22 +/- 8.1%, respectively). Mucin recovery was less with closed suction during conventional 32 +/- 28 microl) and high frequency ventilation (30 +/- 31 microl) than with open suction (382 +/- 235 microl and 24 +/- 153 microl). In the injured lung closed suction was less effective than open suction at recovering thin and thick simulated secretions, irrespective of ventilation mode.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2015
DOI: 10.1097/ALN.0000000000000898
Abstract: Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. The authors hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve gas exchange compared with traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed “multifrequency oscillatory ventilation” (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Thirteen intubated preterm lambs were randomly assigned to either SFOV or MFOV for 1 h, followed by crossover to the alternative regimen for 1 h. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, whereas the customized MFOV waveform consisted of a 5-Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening () and inspired oxygen fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted at 15-min intervals. A ventilatory cost function for SFOV and MFOV was defined as , where Wt denotes body weight. Averaged over all time points, MFOV resulted in significantly lower VC (246.9 ± 6.0 vs. 363.5 ± 15.9 ml2 mmHg kg−1) and (12.8 ± 0.3 vs. 14.1 ± 0.5 cm H2O) compared with SFOV, suggesting more efficient gas exchange and enhanced lung recruitment at lower mean airway pressures. Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared with traditional single-frequency HFOV.
Publisher: American Thoracic Society
Date: 15-02-2006
Publisher: S. Karger AG
Date: 2008
DOI: 10.1159/000143394
Abstract: i Background: /i Therapeutic lung lavage is an emerging treatment for meconium aspiration syndrome (MAS), but the ideal fluid volume and lavage technique remain unclear. i Objective: /i To evaluate the impact of suction technique, chest squeeze and aliquot volume on the efficacy of lung lavage in MAS. i Methods: /i MAS was induced in ventilated 2-week-old piglets using 4 ml/kg of 20% human meconium. Lung lavage with either two 8 ml/kg saline aliquots (n = 5) or a single 15 ml/kg aliquot (n = 6) was performed soon after meconium instillation. Lavage fluid was recovered by three methods performed in sequence: closed suction via a suction adaptor open suction with the ventilator disconnected, and open suction with manual vibratory chest squeezing. Return fluid was collected separately with each method. Recovery of meconium and lavage fluid was determined and expressed as a proportion of the amount instilled. i Results: /i Closed suction resulted in poor meconium and fluid returns, with recovery of meconium being only 5.2 ± (SD) 2.5% with 2 × 8 ml/kg lavage and 19 ± 11% with a single 15 ml/kg aliquot. Chest squeeze during suction increased recovery of both meconium and lavage fluid. Overall recovery of instilled meconium was greater with 15 ml/kg lavage (45 ± 17%) than with two 8 ml/kg aliquots (24 ± 4.5%, p = 0.028, repeated-measures ANOVA) the corresponding values for return of lavage fluid were 73 ± 10 and 49 ± 13%, respectively (p 0.01). i Conclusions: /i Open suction, vibratory chest squeezing and an aliquot volume of 15 ml/kg each improve the efficacy of lung lavage in MAS, and merit inclusion in the lavage technique in clinical trials of this therapy.
Publisher: Wiley
Date: 03-2007
DOI: 10.1111/J.1440-1754.2007.01036.X
Abstract: To examine the use of high frequency ventilation (HFV) to treat newborn infants in Australia and New Zealand and the associated complications and outcomes. Data for all infants receiving HFV were collected from the 28 neonatal intensive care units contributing to the Australian and New Zealand Neonatal Network database between 1996 and 2003, inclusive. For comparison, the same data were gathered on all infants who received conventional mechanical ventilation (CMV) and nasal continuous positive airway pressure. HFV was used to treat 3270 infants (10.1% of all ventilated infants) between 1996 and 2003 uptake doubled during this period from 5.9% to 12.6% of ventilated infants per year. HFV was most frequently applied in the context of extreme prematurity (29.9% of ventilated infants <26 weeks gestation). HFV is being increasingly used to treat complex diseases such as meconium aspiration syndrome and congenital diaphragmatic hernia (12.2% and 10.6% in 1996 to 25.2% and 48.4% in 2003, respectively, chi2 -test for trend, P<0.001). Infants receiving HFV spent longer on respiratory support than infants treated with CMV (median 21 days compared with 7 days, Mann-Whitney test P<0.001) and required a higher initial FiO2 (median 0.8 compared to 0.5, Mann-Whitney test, P<0.001). The use of HFV was associated with a higher mortality than CMV and nasal continuous positive airway pressure (39.7%, 10.1% and 0.4%, chi2 -test, P<0.001). The incidence of death and intraventricular haemorrhage decreased over time in the HFV group (chi2 -test for trend, P<0.001 and P=0.02 respectively). HFV is an established mode of neonatal ventilation in Australia and New Zealand. HFV is being applied to infants at the greatest risk of serious adverse outcomes, most likely as a rescue therapy.
Publisher: Wiley
Date: 09-10-2014
DOI: 10.1111/JPC.12398
Abstract: The aim of this study is to compare the high-frequency pressure litude (oscillatory change in pressure (ΔP)) and tidal volume (high-frequency tidal volume at the airway opening (VTHF )) delivered by the Dräger VN500 (Drägerwerk Ag & Co., Lübeck, Germany) and the Sensormedics 3100 (SM3100 CareFusion, San Diego, CA, USA) through a range of oscillatory frequencies. In this benchtop study, high-frequency oscillations were applied to an infant test lung at unrestricted set litudes. Pressure and flow were measured as a function of frequency, incremented by 1 Hz from 5 to 15 Hz. Measurements were repeated for a range of ventilator settings, and lung resistive and compliance states. The VN500, but not the SM3100, demonstrated an exponential decrease in airway opening ΔP as frequency increased. The difference between the SM3100- and VN500-delivered VTHF became greater with each frequency increment. At 15 Hz, VN500 VTHF was 49% of SM3100 VTHF . The VN500 demonstrates a frequency-related reduction in ΔP not observed in the SM3100. Clinicians need to be aware of these differences in performance characteristics.
Publisher: American Thoracic Society
Date: 05-06-2023
Publisher: American Thoracic Society
Date: 02-2016
Publisher: Springer Science and Business Media LLC
Date: 07-2008
Publisher: American Thoracic Society
Date: 07-2021
Publisher: American Physiological Society
Date: 09-2019
DOI: 10.1152/JAPPLPHYSIOL.00973.2018
Abstract: Pneumothoraxes are common in preterm infants and are a major cause of morbidity. Early detection and treatment of pneumothoraxes are vital to minimize further respiratory compromise. Electrical impedance tomography (EIT) has been suggested as a method of rapidly detecting pneumothoraxes at the bedside. Our objective was to define the EIT-derived regional phase angle differences in filling characteristics before and during spontaneous pneumothoraxes in preterm lambs. Preterm lambs (124–127-day gestation) were ventilated with high-frequency oscillatory ventilation for 120 min. EIT data and cardiorespiratory parameters were monitored continuously and recorded for 3 min every 15 min. Six animals spontaneously developed a pneumothorax within a gravity-nondependent quadrant of the lung and were included for this analysis. Changes in end-expiratory lung impedance (EELI), ventilation, and phase angle delay were calculated in the four lung quadrants at the onset of the pneumothorax and 15 and 30 min prior. At the onset of the pneumothorax, all animals showed a clear increase in EELI in the affected lung quadrant. Fifteen and thirty minutes before the pneumothorax there was a significant phase angle delay between the nondependent and dependent lung. At 1 min before pneumothorax this phase angle delay was isolated just to the affected quadrant (nondependent). These findings are the first description of the events within the lung at initiation of a pneumothorax, demonstrating distinct predictive changes in air-filling characteristics before the occurrence of pneumothorax. This suggests that EIT may be able to accurately identify the onset of a pneumothorax. NEW & NOTEWORTHY In this article we describe for the first time predictive changes in electrical impedance tomography-based regional filling characteristics of the lung before the onset of a one-sided pneumothorax in six preterm lambs ventilated with high-frequency oscillatory ventilation. This can give clinicians bedside information to change treatment of preterm infants and prevent pneumothorax as life-threatening event from happening.
Publisher: BMJ
Date: 08-2008
Abstract: To compare change in lung volume (DeltaV(L)), using respiratory inductive plethysmography, time to recover pre-suction lung volume (t(rec)) and the cardiorespiratory disturbances associated with open suction (OS) and closed suction (CS) in ventilated infants. Randomised blinded crossover trial. Neonatal intensive care unit. Thirty neonates, 20 receiving synchronised intermittent mandatory ventilation (SIMV) and 10 high-frequency oscillatory ventilation (HFOV, four receiving muscle relaxant). OS and CS were performed, in random order, on each infant using a 6FG catheter at -19 kPa for 6 seconds and repeated after 1 minute. DeltaV(L), oxygen saturation (Spo(2)) and heart rate were continuously recorded from 2 minutes before until 5 minutes after suction. Lowest values were identified during the 60 seconds after suction. Variations in all measures were seen during CS and OS. During SIMV no differences were found between OS and CS for maximum DeltaV(L) or t(rec) mean (95% CI) difference of 3.5 ml/kg (-2.8 to 9.7) and 4 seconds (-5 to 13), respectively. During HFOV t(rec) was longer during OS by 13 seconds (0 to 27) but there was no difference in the maximum DeltaV(L) of 0.1 mV (-0.02 to 0.22). A small reduction in SpO(2) with CS in the SIMV group mean difference 6% (2.1 to 9.8) was the only significant difference in physiological measurements. Both OS and CS produced transient variable reductions in heart rate and Spo(2). During SIMV there was no difference between OS and CS in DeltaV(L) or t(rec). During HFOV there was no difference in DeltaV(L) but a slightly longer t(rec) after OS.
Publisher: IOP Publishing
Date: 26-04-2018
Abstract: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode-skin interface and possible adverse effects. Thirty preterm infants (gestational age: 30.3 ± 3.9 week (mean ± SD), postnatal age: 13.8 ± 28.2 d, body weight at inclusion: 1727 ± 869 g) were included in this multicentre study. The electrode-skin contact impedances were measured continuously for up to 3 d and analysed during the initial 20-min phase after fastening the belt and during a 10 h measurement interval without any clinical interventions. The skin condition was assessed by attending clinicians. Our findings imply that the textile electrode interface is suitable for long-term neonatal chest EIT imaging. It does not cause any distress for the preterm infants or discomfort. Stable contact impedance of about 300 Ohm was observed immediately after fastening the electrode belt and during the subsequent 20 min period. A slight increase in contact impedance was observed over time. Tidal variation of contact impedance was less than 5 Ohm. The availability of a textile 32-electrode belt for neonatal EIT imaging with simple, fast, accurate and reproducible placement on the chest strengthens the potential of EIT to be used for regional lung monitoring in critically ill neonates and infants.
Publisher: Springer Science and Business Media LLC
Date: 12-07-2017
DOI: 10.1038/PR.2017.141
Abstract: BackgroundCurrent sustained lung inflation (SI) approaches use uniform pressures and durations. We hypothesized that gestational-age-related mechanical and developmental differences would affect the time required to achieve optimal lung aeration, and resultant lung volumes, during SI delivery at birth in lambs.Methods49 lambs, in five cohorts between 118 and 139 days of gestation (term 142 d), received a standardized 40 cmH
Publisher: Springer Science and Business Media LLC
Date: 15-02-2014
Abstract: Sustained inflations (SI) are advocated for the rapid establishment of FRC after birth in preterm and term infants requiring resuscitation. However, the most appropriate way to deliver a SI is poorly understood. We investigated whether a volume-limited SI improved the establishment of FRC and ventilation homogeneity and reduced lung inflammation/injury compared to a pressure-limited SI. 131 d gestation lambs were resuscitated with either: i) pressure-limited SI (PressSI: 0-40 cmH 2 O over 5 s, maintained until 20 s) or ii) volume-limited SI (VolSI: 0-15 mL/kg over 5 s, maintained until 20 s). Following the SI, all lambs were ventilated using volume-controlled ventilation (7 mL/kg tidal volume) for 15 min. Lung mechanics, regional ventilation distribution (electrical impedance tomography), cerebral tissue oxygenation index (near infrared spectroscopy), arterial pressures and blood gas values were recorded regularly. Pressure-volume curves were performed in-situ post-mortem and early markers of lung injury were assessed. Compared to a pressure-limited SI, a volume-limited SI had increased pressure variability but reduced volume variability. Each SI strategy achieved similar end-inflation lung volumes and regional ventilation homogeneity. Volume-limited SI increased heart-rate and arterial pressure faster than pressure-limited SI lambs, but no differences were observed after 30 s. Volume-limited SI had increased arterial-alveolar oxygen difference due to higher FiO 2 at 15 min (p = 0.01 and p = 0.02 respectively). No other inter-group differences in arterial or cerebral oxygenation, blood pressures or early markers of lung injury were evident. With the exception of inferior oxygenation, a sustained inflation targeting delivery to preterm lambs of 15 mL/kg volume by 5 s did not influence physiological variables or early markers of lung inflammation and injury at 15 min compared to a standard pressure-limited sustained inflation.
Publisher: Cold Spring Harbor Laboratory
Date: 15-06-2020
DOI: 10.1101/2020.06.12.20129379
Abstract: Synchronising positive pressure inflations with an infant’s own breathing is considered lung protective, but the ventilation patterns within the infant lung during synchronous and asynchronous inflations are unknown. The aim of this study was to describe the regional distribution patterns of tidal ventilation within the lung during mechanical ventilation that is synchronous or asynchronous with an infant’s own breathing effort. Intubated infants receiving synchronised mechanical ventilation at The Royal Children’s Hospital NICU were studied. During four 10-minute periods of routine care, regional distribution of tidal volume (V T Electrical Impedance Tomography), delivered pressure and airway flow (Florian Respiratory Monitor) were measured for every inflation. Post hoc, each inflation was then classified as synchronous or asynchronous from video data of the ventilator screen, and the distribution of absolute V T and delivered ventilation characteristics determined. 2749 inflations (2462 synchronous) were analysed in 19 infants mean (SD) age 28 (30) day, GA 35 (5) weeks. Synchronous inflations were associated with a shorter respiratory cycle (p=0.004) and more homogenous V T (centre of ventilation) along the right (0%) to left (100%) lung plane 45.3 (8.6)% vs 48.8 (9.4)% (uniform ventilation 46%). The gravity dependent centre of ventilation was a mean (95% CI) 2.1 (−0.5, 4.6)% more towards the dependent lung during synchronous inflations. Tidal ventilation relative to anatomical lung size was more homogenous during synchronised inflations in the dependent lung. Synchronous mechanical ventilator lung inflations generate more gravity dependent lung ventilation and more uniform right to left ventilation than asynchronous inflations.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.JPEDS.2018.05.029
Abstract: Noninvasive high-frequency oscillatory ventilation compared with nasal continuous positive airway pressure significantly reduced the number of desaturations and bradycardia in preterm infants. However, noninvasive high-frequency oscillatory ventilation was associated with increased oxygen requirements and higher heart rates. Australian and New Zealand Clinical Trial Registry: ACTRN12616001516471.
Publisher: Springer Science and Business Media LLC
Date: 15-09-2009
DOI: 10.1007/S00134-009-1628-8
Abstract: To compare four methods of volume recruitment upon initiation of high frequency oscillatory ventilation (HFOV). Anesthetized intubated neonatal piglets (n = 10) underwent repeated saline lavage, followed by conventional mechanical ventilation (CMV). After transition to HFOV at a mean airway pressure 8 cmH2O above CMV (P(basal)), four methods of lung volume recruitment were tested in each animal in random order: Escalating--step-wise pressure increments over 6 min to a peak mean airway pressure 12 cmH2O above P(basal) Sustained dynamic inflation (DI)--a 20 s inflation to the same peak pressure DI repeated six times for 1 s Standard--mean airway pressure set directly at P(basal). After each recruitment method, HFOV continued at P(basal) for 15 min. Thoracic gas volume and distribution of aeration were determined by single slice computed tomography, and oxygenation by arterial blood gas s ling. Escalating recruitment resulted in the greatest thoracic gas volume 15 min post recruitment [77 +/- 3.3% of total lung capacity vs. 70 +/- 4.2% (Sustained DI), 65 +/- 3.5% (Repeated DI),63 +/- 5.1% (Standard) mean +/- SEM P = 0.042, ANOVA]. All methods resulted in a reduction in non-aerated lung, with the greatest redistribution to normally aerated lung being with Escalating recruitment. Oxygenation 15 min post recruitment was better with the Escalating method than with Repeated DI or Standard recruitment (pO2 307 +/- 41 vs. 159 +/- 36 vs. 134 +/- 39 mmHg, respectively P = 0.016, ANOVA). Escalating recruitment produced the greatest increase in lung volume and resolution of atelectasis, and is recommended for lung volume recruitment upon initiation of HFOV.
Publisher: Springer Science and Business Media LLC
Date: 16-03-2010
DOI: 10.1007/S00134-010-1849-X
Abstract: To examine the impact of different endotracheal tube (ETT) suction techniques on regional end-expiratory lung volume (EELV) and tidal volume (V(T)) in an animal model of surfactant-deficient lung injury. Six 2-week old piglets were intubated (4.0 mm ETT), muscle-relaxed and ventilated, and lung injury was induced with repeated saline lavage. In each animal, open suction (OS) and two methods of closed suction (CS) were performed in random order using both 5 and 8 French gauge (FG) catheters. The pre-suction volume state of the lung was standardised on the inflation limb of the pressure-volume relationship. Regional EELV and V(T) expressed as a proportion of the impedance change at vital capacity (%Z (VCroi)) within the anterior and posterior halves of the chest were measured during and for 60 s after suction using electrical impedance tomography. During suction, 5 FG CS resulted in preservation of EELV in the anterior (non-dependent) and posterior (dependent) lung compared to the other permutations, but these only reached significance in the anterior regions (p < 0.001 repeated-measures ANOVA). V(T) within the anterior, but not posterior lung was significantly greater during 5FG CS compared to 8 FG CS the mean difference was 15.1 [95% CI 5.1, 25.1]%Z (VCroi). Neither catheter size nor suction technique influenced post-suction regional EELV or V(T) compared to pre-suction values (repeated-measures ANOVA). ETT suction causes transient loss of EELV and V(T) throughout the lung. Catheter size exerts a greater influence than suction method, with CS only protecting against derecruitment when a small catheter is used, especially in the non-dependent lung.
Publisher: American Thoracic Society
Date: 08-2016
Publisher: American Thoracic Society
Date: 15-02-2017
Publisher: BMJ
Date: 30-07-2020
DOI: 10.1136/ARCHDISCHILD-2020-319136
Abstract: Skin-to-skin care (SSC) has proven psychological benefits however, the physiological effects are less clearly defined. Regional ventilation patterns during SSC have not previously been reported. This study aimed to compare regional ventilation indices and other cardiorespiratory parameters during prone SSC with supine and prone position cot-nursing. Prospective observational study. Single quaternary neonatal intensive care unit in Australia. 20 infants spontaneously breathing (n=17) or on non-invasive ventilation (n=3), with mean (SD) gestational age at birth of 33 (5) weeks. Thirty-minute episodes of care in each position: supine cot care, prone SSC and prone cot care preceding a 10 min period of continuous electrical impedance tomography measurements of regional ventilation. In each position, ventral–dorsal and right–left centre of ventilation (CoV), percentage of whole lung ventilation by region and percentage of apparent unventilated lung regions were determined. Heart and respiratory rates, oxygen saturation and axillary temperature were also measured. Heart and respiratory rates, oxygen saturation, temperature and right-left lung ventilation did not differ between the three positions (mixed-effects model). Ventilation generally favoured the dorsal lung, but the mean (95% CI) ventrodorsal CoV was −2.0 (−0.4 to –3.6)% more dorsal during SSC compared with prone. Supine position resulted in 5.0 (1.5 to 5.3)% and 4.5 (3.9 to 5.1)% less apparently unventilated lung regions compared with SSC and prone, respectively. In clinically stable infants, SSC generates a distinct regional ventilation pattern that is independent of prone position and results in greater distribution of ventilation towards the dorsal lung.
Publisher: Elsevier BV
Date: 2021
Publisher: American Physiological Society
Date: 2017
DOI: 10.1152/AJPLUNG.00416.2016
Abstract: Respiratory transition at birth involves rapidly clearing fetal lung liquid and preventing efflux back into the lung while aeration is established. We have developed a sustained inflation (SI OPT ) in idualized to volume response and a dynamic tidal positive end-expiratory pressure (PEEP) (open lung volume, OLV) strategy that both enhance this process. We aimed to compare the effect of each with a group managed with PEEP of 8 cmH 2 O and no recruitment maneuver (No-RM), on gas exchange, lung mechanics, spatiotemporal aeration, and lung injury in 127 ± 1 day preterm lambs. Forty-eight fetal-instrumented lambs exposed to antenatal steroids were ventilated for 60 min after application of the allocated strategy. Spatiotemporal aeration and lung mechanics were measured with electrical impedance tomography and forced-oscillation, respectively. At study completion, molecular and histological markers of lung injury were analyzed. Mean (SD) aeration at the end of the SI OPT and OLV groups was 32 (22) and 38 (15) ml/kg, compared with 17 (10) ml/kg (180 s) in the No-RM ( P = 0.024, 1-way ANOVA). This translated into better oxygenation at 60 min ( P = 0.047 2-way ANOVA) resulting from better distal lung tissue aeration in SI OPT and OLV. There was no difference in lung injury. Neither SI OPT nor OLV achieved homogeneous aeration. Histological injury and mRNA biomarker upregulation were more likely in the regions with better initial aeration, suggesting volutrauma. Tidal ventilation or an SI achieves similar aeration if optimized, suggesting that preventing fluid efflux after lung liquid clearance is at least as important as fluid clearance during the initial inflation at birth.
Publisher: Springer Science and Business Media LLC
Date: 25-02-2011
DOI: 10.1007/S00134-011-2157-9
Abstract: Synchronised volume-targeted ventilation (SIPPV + VTV) attempts to reduce lung injury by standardising volume delivery to the preterm lung. The aim of this study is to describe the regional distribution and variability of ventilation within the preterm lung during SIPPV + VTV. Twenty-seven stable, supine, preterm infants with 7 days), supplemental oxygen requirement and set tidal volume. In all sub-groups, the middle third of the chest accounted for the greatest ∆Z (VT) [p 7 days compared with ≤7 days (p < 0.0001, repeated-measures ANOVA). Set tidal volume and oxygen requirement did not significantly influence the regional distribution of ∆Z (VT). The mean (standard deviation, SD) CV of ∆Z (VTANT) and ∆Z (VTPOST) were 30.6% (14.0%) and 31.9% (12.7%). ∆Z (VTANT) and ∆Z (VTPOST) expressed greater breath-to-breath variability than the variation in inflation pressure and V (T) at airway opening (p = 0.012 and p < 0.0001, respectively, paired t-tests). During SIPPV + VTV the preterm infant exhibits marked breath-to-breath variability in regional ventilation which is influenced by age.
Publisher: Australasian Society for Computers in Learning in Tertiary Education
Date: 16-01-2008
DOI: 10.14742/AJET.1228
Abstract: span Many higher education institutions have implemented a learning management system (LMS) to manage online learning and teaching, with varying levels of support provided to staff and students, but often there is little subsequent investigation into the quality of the online sites or the use made of the support structures provided. This paper presents findings from an institutional survey investigating the use of /span em WebCT /em span by academic staff and students in their learning and teaching at a large Australian university. It was expected that student feedback would relate to technical and infrastructure issues, but instead, the survey elicited responses primarily on how /span em WebCT /em span was used in teaching and learning, indicating that quality control is a major issue for the University. Student opinions appear to reflect more the use of the technology made by teaching staff - students who have experienced a well-designed unit rich with resources, timely feedback and good interaction with staff reported a positive experience with the technology. Staff responses are more focused on the technical and administrative aspects of using /span em WebCT /em span rather than teaching issues. The findings in this paper have implications for quality teaching and learning with technology, and the way in which tertiary institutions support academic staff. /span
Publisher: Cold Spring Harbor Laboratory
Date: 30-07-2020
DOI: 10.1101/2020.07.29.20161166
Abstract: The transition to air-breathing at birth is a seminal, but poorly understood, respiratory event common to all humans. The objectives of this prospective, observational study were to describe the spatiotemporal gas flow, aeration and ventilation patterns occurring within the lung in neonates during successful respiratory transition. Electrical impedance tomography was used to image intrathoracic volume patterns for every breath until six minutes from birth in term infants not needing resuscitation. Breaths were classified by video data, and measures of lung aeration, tidal flow conditions and intrathoracic volume distribution calculated for each inflation. 1401 breaths (n=17 neonates) met eligibility and data analysis criteria. Stable functional residual capacity was obtained by median (IQR) 43 (21, 77) breaths. Breathing patterns changed from predominantly crying (80.9% first minute) to tidal breathing (65.3% sixth minute). Tidal ventilation was inhomogeneous at birth, favouring the right and non-dependent lung p .001 versus left and dependent lung (mixed effects model). Initial crying created a unique pattern with delayed mid-expiratory gas flow associated with intrathoracic volume redistribution (pendelluft flow) within the lung. This preserved functional residual capacity (70.8% cries), especially within the dorsal and right lung. The commencement of air-breathing at birth generates unique flow and volume states associated with marked spatiotemporal ventilation inhomogeneity not seen elsewhere in respiratory physiology. At birth neonates innately brake expiratory flow to defend functional residual capacity gains and redistribute gas to less aerated regions. National Health and Medical Research Council (Australia). Birth requires the rapid transition from a fluid-filled to aerated lung. Despite being a seminal event for all humans, very little is understood about the physiological processes supporting the transition to air-breathing. Radiological and interventional studies from more than 40 years ago suggest that respiratory success at birth requires high intrathoracic pressure and flow states. Imaging studies in animals indicate that braking expiratory flow aids generating functional residual capacity. In term neonates during successful respiratory transition, breath-by-breath imaging of the intrathoracic gas flow and volume patterns within the lungs was possible with electrical impedance tomography. We found that aeration and ventilation were not uniform, with highly inhomogeneous, spatiotemporal volume patterns during attainment of functional residual capacity. Crying at birth created a unique expiratory pattern that allowed intrathoracic volume redistribution (pendelluft flow) within the lung, and preserved functional residual capacity. We hypothesise that newborns defend aeration from intrathoracic lung-fluid shifts by innately braking flow using the glottis and diaphragm. Real-time imaging of intrathoracic volume patterns in humans is practical and may offer measures that identify neonates needing resuscitation. Whilst inspiration generated aeration, expiration is equally important to the respiratory transition. Expiratory braking is essential as a mechanism of defending aeration suggesting that positive end-expiratory pressure is likely to be the most important method of supporting the failing human lung at birth.
Publisher: Frontiers Media SA
Date: 21-08-2019
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2016
End Date: 2018
Funder: National Health and Medical Research Council
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Funder: National Health and Medical Research Council
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Funder: National Health and Medical Research Council
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Funder: National Health and Medical Research Council
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Funder: National Health and Medical Research Council
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