ORCID Profile
0000-0002-1605-8843
Current Organisations
University of Sydney
,
Westmead Hospital
,
Royal Australasian College of Physicians
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Publisher: Wiley
Date: 03-2003
Publisher: Wiley
Date: 05-1999
DOI: 10.1097/00005537-199905000-00018
Abstract: Inspiratory flow limitation associated with collapse of the nasal vestibular walls is a feature of nasal breathing at high ventilatory levels. We examined whether an external nasal dilator strip (ENDS) device (Breathe Right, CNS Inc., Chanhassen, MN) influences maximum inspiratory and expiratory flow rates. Prospective, randomized. We studied 20 Caucasian subjects (13 female, 7 male age range, 16-49 y) performing maximum-effort nasal flow-volume loop studies with (ENDS) and without ENDS (control) and following topical nasal decongestant (oxymetazoline hydrochloride, 0.2 mg per nostril). ENDS increased peak inspiratory flow from 2.55+/-0.24 L/s (mean+/-standard error [SE]) to 2.86+/-0.25 L/s and forced inspiratory flow at 50% of vital capacity from 2.23+/-0.24 L/s to 2.53+/-0.24 L/s (both, P<.0001), but had no effect on maximum expiratory flows. Nasal decongestant increased the forced expiratory volume in 1 second from 3.39+/-0.22 L/s to 3.59+/-0.22 L/s and the average forced expiratory flow over 25% to 75% of vital capacity from 3.31+/-0.31 L/s to 3.61+/-0.28 L/s (both, P< or = .008), but had no effect on maximum inspiratory flows. The combination of decongestant and ENDS increased both inspiratory and expiratory maximum flows. Since ENDS selectively increases maximum nasal inspiratory flow rates, we conclude that ENDS increases inspiratory nasal patency during maximum inspiratory efforts through the nose by supporting the lateral nasal vestibular walls and making them more resistant to collapse.
Publisher: American Physiological Society
Date: 11-2003
DOI: 10.1152/JAPPLPHYSIOL.00488.2003
Abstract: Lowering surface tension (γ) of upper airway lining liquid (UAL) reduces upper airway opening (anesthetized humans) and closing (anesthetized rabbits) pressures. We now hypothesize that in sleeping obstructive sleep apnea hypopnea syndrome (OSAHS) patients lowering γ of UAL will enhance upper airway stability and decrease the severity of sleep-disordered breathing. Nine OSAHS patients [respiratory disturbance index (RDI): 49 ± 8 (SE) events/h, diagnostic night] participated in a two-part, one-night, polysomnography study. In the first part, upper airway closing pressures (during non-rapid eye movement sleep, Pcrit) were measured and s les of UAL (awake) were obtained before and after 2.5 ml of surfactant (Exosurf, Glaxo Smith Kline) was instilled into the posterior pharynx. The γ of UAL was determined with the use of the “pull-off” force technique. In the second part, subjects received a second application of 2.5 ml of surfactant and then slept the remainder of the night (205 ± 30 min). Instillation of surfactant decreased the γ of UAL from 60.9 ± 3.1 mN/m (control) to 45.2 ± 2.5 mN/m (surfactant group) ( n = 9, P 0.001). Pcrit decreased from 1.19 ± 1.14 cmH 2 O (control) to -0.56 ± 1.15 cmH 2 O (surfactant group) ( n = 7, P 0.02). Compared with the second half of diagnostic night, surfactant decreased RDI from 51 ± 8 to 35 ± 8 events/h ( n = 9, P 0.03). The fall in RDI (ΔRDI) correlated with the fall in γ of UAL (Δγ) (ΔRDI = 1.8 × Δγ, r = 0.68, P = 0.04). Hypopneas decreased ∼50% from 42 ± 8 to 20 ± 5 events/h ( n = 9, P 0.03, paired t-test). The γ of UAL measured the next morning remained low at 49.5 ± 2.7 mN/m ( n = 9, P 0.001, ANOVA, compared with control). In conclusion, instillation of surfactant reduced the γ of UAL in OSAHS patients and decreased Pcrit and the occurrence of hypopneas. Therapeutic manipulation of γ of UAL may be beneficial in reducing the severity of sleep-disordered breathing in OSAHS patients.
Publisher: IOP Publishing
Date: 22-12-2010
DOI: 10.1088/0967-3334/32/2/006
Abstract: The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (β(1) = 1.08 V L(-1) s(-1) β(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow litude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data validate the pitot flowmeter for quantification of airflow and detecting breathing reduction during polysomnographic sleep studies. We speculate that quantifying airflow during sleep can differentiate phenotypic traits related to sleep disordered breathing.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2014
DOI: 10.1007/S11325-013-0845-0
Abstract: We used statistical modelling to probe the contributions of anthropometric and surface cephalometric variables to the OSA phenotype. The design is prospective cohort study. The setting is community-based and sleep disorder laboratory. Study #1-Model development study: 147 healthy asymptomatic volunteers (62.6 % Caucasian age, 18-76 years 81 females median multivariable apnea prediction index=0.15) and 140 diagnosed OSA patients (84.3 % Caucasian age, 18-83 years 41 females polysomnography [PSG] determined apnea-hypopnea index >10 events/h). Study #2-Model test study: 345 clinic patients (age, 18-86 years 129 females) undergoing PSG for diagnosis of OSA. We measured 10 anthropometric and 34 surface cephalometric dimensions (calipers) and calculated mandibular enclosure volumes for study #1 and recorded age and neck circumference for study #2. Statistical modelling included principal component (PC), logistic regression, and receiver-operator curve analyses. Model development study: A regression model incorporating three identified PC predicted OSA with 88 % sensitivity and specificity. However, a simplified model based on age and NC alone was equally effective (87 % sensitivity and specificity). Model test study: The simplified model predicted OSA with high sensitivity (93 %) but poor specificity (21 %). We conclude that in our clinic-based cohort, craniofacial bony and soft tissue structures (excluding neck anatomy) do not play a substantial role in distinguishing patients with OSA from those without. This may be because craniofacial anatomy does not contribute greatly to the pathogenesis of OSA in this group or because referral bias has created a relatively homogeneous phenotypic population.
Publisher: Wiley
Date: 04-09-2014
DOI: 10.1111/JSR.12079
Publisher: Elsevier BV
Date: 12-1999
Abstract: To measure route of breathing in chronic asthmatic patients during and after an acute severe exacerbation. Thirteen asthmatic patients were studied during hospital admission for acute asthma and, in 9 patients, again when asymptomatic. Nine healthy subjects were also studied. Spontaneous route of breathing was qualitatively assessed using oral and nasal thermistor probes, and was then quantified using a dual compartment face mask with attached pneumotachographs. All asthmatic patients had severe bronchoconstriction initially (FEV(1), 46 +/- 3% of predicted) that had resolved at follow-up (FEV(1), 91 +/- 6% of predicted). No healthy subject had evidence of bronchoconstriction (FEV(1), 102 +/- 5% of predicted). During acute asthma, 11 asthmatics were spontaneously breathing oronasally, as assessed using thermistor probes, while all 13 breathed oronasally via face mask. When assessed using thermistor probes, seven of nine asymptomatic asthmatic patients studied were breathing exclusively via the nose however, all breathed oronasally via face mask. In contrast, while eight of nine healthy subjects were also breathing exclusively via the nose when assessed using thermistor probes, all breathed nasally only via face mask. Thus, when asymptomatic and at rest, asthmatic patients breathe exclusively via the nose. However, during acute exacerbations of asthma, these patients switch to oronasal breathing. Unlike healthy subjects, chronic asthmatic patients also switch to oronasal breathing when wearing a face mask, irrespective of the degree of bronchoconstriction. We speculate that asthmatics may have an increased tendency to switch to oral breathing, a factor that may contribute to the pathogenesis of their asthma.
Publisher: Elsevier BV
Date: 05-2005
DOI: 10.1016/J.TUBE.2004.06.003
Abstract: Nine university-affiliated chest clinics in Australia. To evaluate the sensitivity of a whole blood human gamma-interferon assay (HGIA, QuantiFERON-TB) for specific T lymphocyte responses and Tuberculin skin testing (TST) for the detection of Mycobacterium tuberculosis infection in subjects with culture-proven M. tuberculosis disease (TBCP). Prospective testing of 129 patients with recent TBCP and 100 patients with non-tuberculosis lung disease (NTBLD). Using a defined level of specific IFN-gamma production and TST 10mm as positive cut-offs, the sensitivity of HGIA was 81% compared to 89% for TST (p=0.06). When positive responses in both TST and HGIA were combined, 96% of TB patients were detected. For the NTBLD group, 43% of whom were born overseas, 73% were negative for both the HGIA and TST. Prior immunization with M. bovis (bacille Calmette-Guerin) (BCG) or the type of TB had no effect on the sensitivities of the assays. For those treated for 2 months the sensitivity of TST (90%) tended to be higher than for HGIA (81%) (p=0.07). The distribution of TST results in TB patients showed a broad peak between 10 and 25 mm, while the results in the HGIA were bimodal in both TB and NTBLD patients. HGIA may prove an alternative to skin testing for detecting M. tuberculosis infection in certain settings.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Oxford University Press (OUP)
Date: 02-2007
Abstract: To investigate the mechanisms via which lung volume related caudal tracheal traction decreases upper airway collapsibility. Acute physiological study. 20 male, supine, anesthetised, tracheostomised, spontaneously breathing, NZ white rabbits fitted with a sealed face mask. N/A. Upper airway extraluminal tissue pressure (ETP) was measured in the lateral (ETPlat) and anterior (ETPant) pharyngeal walls (pressure transducer tipped catheters). Graded traction was applied to the isolated upper airway (n = 17, 0-140 g). Subsequently, inflation and deflation was performed (with and without traction, 48 g, n = 13) with measurement of intraluminal pressure. Upper airway transmural pressure (PTM) was calculated (at closure and reopening) for both ETP sites (PTMlat and PTMant, respectively). A traction force of 144 g decreased ETPlat from 2.6 +/- 0.7 cm H2O (mean +/- SEM) to 2.1 +/- 0.7 cm H2O and ETPant from 1.1 +/- 0.4 cm H2O to 0.8 +/- 0.4 cm H2O (both P < 0.001). Increasing traction decreased closing and reopening pressures by 1.4 +/- 0.2 cm H2O for 48 g of traction (n = 13, P < 0.0001). In addition, 48 g of traction decreased ETPlat (at closure and reopening) by 0.2 +/- 0.05 cm H2O (P < 0.0001), and decreased ETPant by 0.5 +/- 0.1 cm H2O at closing pressure and 0.8 +/- 0.1 cm H2O at reopening (both p < 0.0001). Thus, for 48 g of traction, PTMlat (at closure and reopening) fell by 1.1 +/- 0.2 cm H2O and PTMant (reopening only) fell by 0.9 +/- 0.3 cm H2O (all P < 0.0001). Since tracheal traction decreased PTMlat and PTMant by a greater amount than ETPlat and ETPant, we conclude that the decrease in upper airway collapsibility mediated by lung volume related caudal tracheal traction is partially explained by reductions in ETP.
Publisher: American Physiological Society
Date: 05-2006
DOI: 10.1152/JAPPLPHYSIOL.01439.2005
Abstract: Epidemiological studies link habitual snoring and stroke, but mechanisms involved are poorly understood. One previously advanced hypothesis is that transmitted snoring vibration energy may promote carotid atheromatous plaque formation or rupture. To test whether vibration energy is present in carotid artery walls during snoring we developed an animal model in which we examined induced snoring (IS)-associated tissue energy levels. In six male, supine, anesthetized, spontaneously breathing New Zealand White rabbits, we surgically inserted pressure transducer-tipped catheters (Millar) to monitor tissue pressure at the carotid artery bifurcation (P CT ) and within the carotid sinus lumen (P CS artery ligated). Snoring was induced via external compression (sandbag) over the pharyngeal region. Data were analyzed using power spectral analysis for frequency bands above and below 50 Hz. For frequencies below 50 Hz, P CT energy was 2.2 (1.1–12.3) cmH 2 O 2 [median (interquartile range)] during tidal breathing (TB) increasing to 39.0 (2.5–95.0) cmH 2 O 2 during IS ( P = 0.05, Wilcoxon's signed-rank test). For frequencies Hz, P CT energy increased from 9.2 (8.3–10.4) × 10 −4 cmH 2 O 2 during TB to 172.0 (118.0–569.0) × 10 −4 cmH 2 O 2 during IS ( P = 0.03). Concurrently, P CS energy was 13.4 (8.5–18.0) × 10 −4 cmH 2 O 2 during TB and 151.0 (78.2–278.8) × 10 −4 cmH 2 O 2 during IS ( P 0.03). The P CS energy was greater than P CT energy for the 100–275 Hz bandwidth. In conclusion, during IS there is increased energy around and within the carotid artery, including lower frequency lification for P CS . These findings may have implications for carotid atherogenesis and/or plaque rupture.
Publisher: American Physiological Society
Date: 02-2014
DOI: 10.1152/JAPPLPHYSIOL.00668.2014
Abstract: Mandibular advancement (MA) increases upper airway (UA) patency and decreases collapsibility. Furthermore, MA displaces the hyoid bone in a cranial-anterior direction, which may contribute to MA-associated UA improvements via redistribution of peripharyngeal tissue stresses (extraluminal tissue pressure, ETP). In the present study, we examined effects of MA on ETP distributions, deformation of the peripharyngeal tissue surface (UA geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing adult male New Zealand White rabbits. Graded MA was applied from 0 to ∼4.5 mm. ETP was measured at six locations distributed throughout three UA regions: tongue, hyoid, and epiglottis. Axial computed tomography images of the UA (nasal choanae to glottis) were acquired and used to measure lumen geometry (UA length regional cross-sectional area) and hyoid displacement. MA resulted in nonuniform decreases in ETP (greatest at tongue region), ranging from −0.11 (−0.15 to −0.06) to −0.82 (−1.09 to −0.54) cmH 2 O/mm MA [linear mixed-effects model slope (95% confidence interval)], across all sites. UA length decreased by −0.5 (−0.8 to −0.2) %/mm accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 7.5 (3.6–11.4) to 18.7 (14.9–22.5) %/mm. The hyoid bone was displaced in a cranial-anterior direction by 0.42 (0.36–0.44) mm/mm MA. In summary, MA results in nonuniform changes in peripharyngeal tissue pressure distributions and lumen geometry. Displacement of the hyoid bone with MA may play a pivotal role in redistributing applied MA loads, thus modifying tissue stress/deformation distributions and determining resultant UA geometry outcomes.
Publisher: American Physiological Society
Date: 2006
DOI: 10.1152/JAPPLPHYSIOL.00560.2005
Abstract: The pharyngeal airway can be considered as an airway luminal shape formed by surrounding tissues, contained within a bony enclosure formed by the mandible, skull base, and cervical vertebrae. Mandibular advancement (MA), a therapy for obstructive sleep apnea, is thought to increase the size of this bony enclosure and to decrease the pressure in the upper airway extraluminal tissue space (ETP). We examined the effect of MA on upper airway airflow resistance (Rua) and ETP in a rabbit model. We studied 11 male, supine, anesthetized, spontaneously breathing New Zealand White rabbits in which ETP was measured via pressure transducer-tipped catheters inserted into the tissues surrounding the lateral (ETPlat) and anterior (ETPant) pharyngeal wall. Airflow, measured via surgically inserted pneumotachograph in series with the trachea, and tracheal pressure were recorded while graded MA at 75° and 100° to the horizontal was performed using an external traction device. Data were analyzed using a linear mixed-effects statistical model. We found that MA at 100° increased mouth opening from 4.7 ± 0.4 to 6.6 ± 0.4 (SE) mm ( n = 7 P 0.004), whereas mouth opening did not change from baseline (4.0 ± 0.2 mm) with MA at 75°. MA at both 75° and 100° decreased mean ETPlat and ETPant by ∼0.1 cmH 2 O/mm MA ( n = 7–11 all P 0.0005). However, the fall in Rua (measured at 20 ml/s) with MA was greater for MA at 75° (∼0.03 mmH 2 O·ml −1 ·s·mm −1 ) than at 100° (∼0.01 mmH 2 O·ml −1 ·s·mm −1 P 0.02). From these findings, we conclude that MA decreases ETP and is more effective in reducing Rua without mouth opening.
Publisher: American Thoracic Society
Date: 09-1993
Abstract: An important mechanism controlling genioglossus (GG) muscle activity is the reflex response to negative airway pressure. We hypothesize that this reflex response may be lost during sleep and believe that this loss may be important in the pathogenesis of airway collapse during sleep. Thus, we determined the effect of non-rapid eye movement (NREM) sleep on the GG electromyogram (EMG) response to brief (0.2 to 0.6 s) episodes of negative pressure generation (NPG) in the upper airway of six normal subjects. Up to 100 NPGs (mean 58 +/- 12) were recorded both awake and during stable NREM sleep. During wakefulness, the change in GG moving time average EMG from basal to peak levels (during NPG) was 17.1 +/- 2.5 au (a 154 +/- 22% increase above basal levels). This response was markedly reduced during NREM sleep (2.7 +/- 1.2 au p < 0.01). The latency of the GG EMG response was 53.8 +/- 11.5 ms during wakefulness (n = 6), but much longer during sleep (132.7 +/- 24.5 ms n = 3 p < 0.03). We conclude that in normal subjects (1) the GG muscle responds to negative airway pressure by reflex activation during wakefulness, and (2) this reflex activation is reduced or lost during NREM sleep. We speculate that loss of this mechanism during sleep may contribute to pharyngeal collapse in obstructive apnea patients.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-1998
DOI: 10.1097/00063198-199811000-00011
Abstract: Abnormalities of upper airway mechanical properties are a well-recognized and important feature of the pathophysiology of the obstructive sleep apnea hypopnea syndrome (OSAHS). Recently, investigations enhanced our understanding of the factors that promote upper airway obstruction. In patients with OSAHS, anatomic narrowing of the pharyngeal airway, particularly in the lateral dimension with thickening of the lateral pharyngeal walls, is present. In addition, the passive upper airway (absent muscle activity) demonstrates increased collapsibility, which is modulated by caudal tracheal traction, mucosal surface forces, route of breathing, and the balance of intraluminal airway and extraluminal tissue pressures. In patients with OSAHS, pharyngeal dilator muscles (including the genioglossus and soft palate muscles) demonstrate a coordinated pattern of increased muscle activity while awake compared with normals. This is thought to represent a neuromuscular compensatory mechanism for the anatomically narrow, more collapsible upper airway. With the onset of sleep, the reflexes that drive this muscular compensation are diminished, leading to reduced muscle activity and predisposing the OSAHS patient to pharyngeal collapse. Better understanding of the mechanical properties of the upper airway in normals and patients with OSAHS should help in the development of new therapeutic strategies.
Publisher: IOP Publishing
Date: 20-02-2014
DOI: 10.1088/0967-3334/35/3/455
Abstract: We examined thermocouple and pressure cannulae responses to oral and nasal airflow using a polyester model of a human face, with patent nasal and oral orifices instrumented with a dual thermocouple (F-ONT2A, Grass) or a dual cannula (0588, Braebon) pressure transducer (± 10 cm H2O, Celesco) system. Tidal airflow was generated using a dual compartment facemask with pneumotachographs (Fleisch 2) connected to the model orifices. During nasal breathing: thermocouple litude = 0.38 Ln [pneumotachograph litude] + 1.31 and pressure cannula litude = 0.93 [pneumotachograph litude](2.15) during oral breathing: thermocouple litude = 0.44 Ln [pneumotachograph litude] + 1.07 and pressure cannula litude = 0.33 [pneumotachograph litude](1.72) (all range ∼ 0.1-∼ 4.0 L s(-1) r(2) > 0.7). For pneumotachograph litudes <1 L s(-1) (linear model) change in thermocouple litude/unit change in pneumotachograph litude was similar for nasal and oral airflow, whereas nasal pressure cannula litude/unit change in pneumotachograph litude was almost four times that for oral. Increasing oral orifice area from 0.33 cm(2) to 2.15 cm(2) increased oral thermocouple litude/unit change in pneumotachograph litude by ∼ 58% but decreased pressure cannula litude/unit change in pneumotachograph litude by 49%. For pneumotachograph litudes up to 1 L s(-1), alterations in inspiratory/expiratory ratios or total respiratory time did not affect the sensitivity of either nasal or oral pressure cannulae or the nasal thermocouple, but the oral thermocouple sensitivity was influenced by respiratory cycle time. Different nasal and oral responses influence the ability of these systems to quantitatively assess nasal and oral airflow and oro-nasal airflow partitioning.
Publisher: Oxford University Press (OUP)
Date: 08-1999
Publisher: Springer Science and Business Media LLC
Date: 23-01-2021
DOI: 10.1007/S11325-021-02300-8
Abstract: REM-related obstructive sleep apnea (REM-OSA), as defined using revised apnea-hypopnea index (AHI) criteria, might represent a specific OSA phenotype. However, there is a lack of data on outcomes of treatment in this population. This study evaluated the effects of CPAP treatment over 12 months on clinical outcomes for patients with the polysomnography phenotype of REM-OSA. We conducted a prospective observational study with the following inclusion criteria: subjective sleepiness and diagnostic polysomnography demonstrating AHI Twenty participants completed a minimum of 1 month of CPAP treatment and were included for analysis. During the trial, 8 participants discontinued CPAP (4 before 3 months, 1 before 6 months, 3 before 12 months), and 19 participants completed 12 months of treatment. Baseline ESS was elevated at 12.6 units. Average CPAP usage for all 27 participants over 12 months was 2.9 ± 2.4 h. There was a significant decrease in ESS and increase in FOSQ at all time points, and the decrease in ESS was only seen in the CPAP-adherent subgroup. Decreases in DASS-21 and PVT-RT were not sustained. CPAP treatment in sleepy patients with moderate to severe REM-OSA is associated with reduced sleepiness and improved quality of life. The trial was registered in the Australian New Zealand Clinical Trials Registry: ACTRN12620000576921, 18/05/2020 (retrospectively registered).
Publisher: American Physiological Society
Date: 15-03-2015
DOI: 10.1152/JAPPLPHYSIOL.00691.2014
Abstract: Mechanical processes underlying pharyngeal closure have not been examined. We hypothesized that the pharyngeal mucosal surface would fold during closure, and lowering the upper airway lining liquid surface tension would unfold areas of mucosal apposition, i.e., folds. We compared baseline pharyngeal fold numbers and response to reduction in upper airway liquid surface tension in healthy and obstructive sleep apnea (OSA) subjects. Awake, gated magnetic resonance pharyngeal airway images of 10 healthy and 11 OSA subjects were acquired before and after exogenous surfactant administration (beractant). Upper airway liquid surface tension was measured at the beginning and end of image acquisition and averaged. Velopharyngeal and oropharyngeal images were segmented and analyzed separately for average cross-sectional area, circumference, and fold number. Compared with healthy subjects, at baseline, velopharynx for OSA subjects had a smaller cross-sectional area (98.3 ± 32.5 mm 2 healthy, 52.3 ± 23.6 mm 2 OSA) and circumference (46.5 ± 8.1 mm healthy, 30.8 ± 6.1 mm OSA both P 0.05, unpaired t-test), and fewer folds (4.9 ± 1.6 healthy, 3.1 ± 1.8 OSA, P 0.03). There were no differences in oropharynx for cross-sectional area, circumference, or folds. Reduction in upper airway liquid surface tension from 61.3 ± 1.2 to 55.3 ± 1.5 mN/m ( P 0.0001) did not change cross-sectional area or circumference for velopharynx or oropharynx in either group however, in OSA subjects, oropharyngeal folds fell from 6.8 ± 3.1 to 4.7 ± 1.2 ( n = 8, P 0.05), and velopharyngeal folds from 3.3 ± 1.9 to 2.3 ± 1.2 ( P = 0.08), and were unchanged in healthy subjects. Subjects with OSA have fewer velopharyngeal wall folds, which decrease further when surface tension falls. We speculate that reduced pharyngeal wall folds contribute to an increase in pharyngeal collapsibility.
Publisher: European Respiratory Society (ERS)
Date: 07-2005
DOI: 10.1183/09031936.05.00144704
Abstract: Lung function is commonly used as the primary endpoint in asthma clinical trials, but it may not reflect changes which are important to patients. The present study compared changes in, and relationships between, traditional and patient-centred end-points during treatment with three classes of asthma medication. Subjects with mild-to-moderate asthma were randomised to double-blind, double-dummy crossover treatment with eformoterol 12 microg b.i.d. or montelukast 10 mg q.d., then single-blind treatment with fluticasone 250 microg b.i.d. lacebo capsules, with 6-week treatment periods and 1-week washouts. In idual "traditional" end-points (symptoms, reliever use, forced expiratory volume in one second per cent predicted, morning peak expiratory flow, airway hyperresponsiveness) and "patient-centred" end-points (asthma control questionnaire, quality of life, patient global assessments) were assessed. Principal component analysis and linear modelling were used to explore overall rank orders for treatment, and relationships between outcomes. A total of 58 subjects were randomised. The rank order of benefit from eformoterol and fluticasone differed for three factors derived from principal component analysis (eformoterol>fluticasone for symptom/reliever use factor, fluticasone>eformoterol for lung function factor, eformoterol=fluticasone for patient-centred factor). Montelukast was ranked third for all three factors. A significant relationship between patient-based variables and lung function was found only for montelukast treatment. In asthma treatment, traditional end-points do not fully capture patient-centred benefits, and the relationship between end-points differs with medication class.
Publisher: Wiley
Date: 20-01-2015
DOI: 10.1111/RESP.12471
Abstract: The 6-min walk test (6MWT) is a simple test assessing functional capacity, but concerns about risks of substantial oxygen desaturation in pulmonary patients have led to non-adherence to the standardised American Thoracic Society guideline. We evaluated the safety of the 6MWT in stable COPD patients and compared the incidence of adverse events in patients with and without substantial exertional hypoxaemia. 6MWT data were obtained for 1136 patients with moderate to very severe COPD. Demographics, adverse events, oxygen saturation (SpO2), 6-min walk distance, lung function and quality of life measures were compared between patients with substantial exertional hypoxaemia (nadir SpO2 < 85%) and those without (SpO2 ≥ 85%). Comparisons were made using Mann-Whitney U-test for continuous variables and Fisher's exact test for categorical variables. Twenty-five patients (2.2%) had adverse events, the most common being dizziness, chest tightness, chest pain and palpitations. Substantial exertional hypoxaemia did not increase the incidence of adverse events. No significant morbidity or mortality was recorded. Patients with adverse events had lower baseline SpO2, worse quality of life scores, and higher depression and anxiety scores. However, no significant differences were seen in anthropometric data, spirometric values or SpO2 during and after the 6MWT. Asymptomatic exertional hypoxaemia is not associated with an increased incidence of adverse events during 6MWT in COPD patients. Our data support the ATS guideline that the 6MWT should be continued in the absence of symptoms and that intermittent oximetry monitoring does not assist in preventing adverse events.
Publisher: Springer Science and Business Media LLC
Date: 12-2005
Abstract: Inhaled mannitol is a new bronchial provocation test (BPT) developed to improve portability and standardisation of osmotic challenge testing. Osmotic challenge tests have an advantage over the traditional methods of measuring airway hyperresponsiveness using methacholine as they demonstrate higher specificity to identify asthma and thus the need for treatment with inhaled corticosteroids (ICS). The safety and the efficacy of mannitol (M) as a BPT to measure airway hyperresponsiveness were compared to hypertonic (4.5%) saline (HS) in people both with and without signs and symptoms of asthma. A phase III, multi-centre, open label, operator-blinded, crossover design, randomised trial, with follow-up. Asthmatics and non-asthmatics (6–83 yr) were recruited and 592 subjects completed the study. Mannitol was delivered using a low resistance dry powder inhaler and HS was delivered using an ultrasonic nebuliser. The FEV 1 was measured 60 seconds after each dose of mannitol (5,10,20,40,80,160,160,160 mg) and after each exposure to HS (0.5,1.0,2.0,4.0,8.0 minutes). A 15% fall in FEV 1 defined a positive test. Adverse events were monitored and diaries kept for 7 days following the tests. Mean pre-test FEV1 (mean ± SD) was 95.5 ± 14% predicted. 296 were positive to mannitol (M+) and 322 positive to HS (HS+). A post study physician conducted clinical assessment identified 82.3% asthmatic (44% classified mild) and 17.7% non-asthmatic. Of those M+, 70.1% were taking ICS and of those mannitol negative (M-), 81.1 % were taking ICS. The % fall in FEV1 for mannitol in asthmatics was 21.0% ± 5.7 and for the non-asthmatics, 5.5% ± 4.8. The median PD15 M was 148 mg and PD15 HS 6.2 ml. The sensitivity of M to identify HS+ was 80.7% and the specificity 86.7%. The sensitivity of M compared with the clinical assessment was 59.8% and specificity 95.2% and increased to 88.7% and 95.0% respectively when the M- subjects taking ICS were excluded. Cough was common during testing. There were no serious adverse events. The diarised events were similar for mannitol and HS, the most common being headache (17.2%M, 19%HS), pharyngolaryngeal pain (5.1%M, 3%HS), nausea (4.3%M, 3%HS), and cough (2.2%M, 2.4%HS). The efficacy and safety of mannitol was demonstrated in non-asthmatic and clinically diagnosed asthmatic adults and children.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2000
DOI: 10.1097/00005768-200002000-00006
Abstract: Mouthguards worn during sporting competition may influence oral airway flow dynamics and potentially increase airflow resistance during mouth breathing. We measured oral airflow resistance (RO) in 10 normal subjects (four men, six women, age 29 +/- 3 yr, mean +/- SEM) wearing two different custom-made maxillary mouthguards. During tidal mouthpiece breathing (jaw position controlled), inspiratory R(O) (at (1.4 L x s(-1)) increased from 0.22 (0.15-0.46) cm H2O x L(-1) x s(-1) (median and interquartile range) to 0.47 (0.24-0.52) cm H2O x L(-1) x s(-1) with mouthguard 1 (general sports mouthguard) and from 0.34 (0.27-0.51) to 0.46 (0.39-0.86) cm H2O x L(-1) x s(-1) (N = 8) with mouthguard 2 (laminated, field hockey mouthguard, both P < 0.05). With oral only mask breathing (jaw position not controlled), inspiratory R(O) (at 0.4 L x s(-1)) increased to 1.02 (0.42-1.57) cm H2O x L(-1) x s(-1) (P < 0.03, compared with mouthpiece) but was variably affected by both mouthguards. At 1.0 L x s(-1), there was a tendency for both mouthguards to increase inspiratory R(O) however, this effect only reached significance for mouthguard 1 during mouthpiece breathing. Thus, although maxillary mouthguards do increase R(O) when jaw position is controlled, in idual subjects respond differently when in control of mouth opening. This may be related to variable recruitment of compensatory mechanisms (e.g. mouth opening and/or oral airway dilator muscle activity).
Publisher: IOP Publishing
Date: 13-06-2005
DOI: 10.1088/0967-3334/26/5/009
Abstract: Upper airway luminal patency is influenced by a number of factors including: intraluminal air pressure, upper airway dilator muscle activity, surrounding extraluminal tissue pressure and surface tension acting within the liquid layer lining the upper airway. In this study we examine the performance characteristics for the 'pull-off' force method for measuring the surface tension (gamma) of liquids. This method is then used to examine the gamma of the liquid lining the oro-pharynx in awake human subjects. The gamma of UAL s les (approximately 0.2 microL) obtained from the posterior pharyngeal wall was quantified using the pull-off force technique in which gamma is measured as the force required to separate two curved silica discs bridged by the liquid s le. Pull-off force measurement was not influenced by s le volumes or under different temperature or humidity conditions. The coefficients of variation for repeated measurements using the pull-off force technique for the three standard liquids ranged from 1.2% to 5.6%. The pull-off method tended to give slightly lower values than the Wihelmy balance method with the mean difference being 2.4 +/- 1.8 mN m(-1). For the group, the gamma of saliva was 59.2 +/- 0.6 mN m(-1) (CV 4.9 +/- 0.9%) for five measurements of a single s le. There was no significant relationship between the measured gamma values for five subjects measured on five separate days and the day of collection of the s le for any of the subjects or the group as a whole (both p > 0.6). There was no significant difference (p = 0.53, ANOVA) between the gamma values for s les obtained from under the tongue (61.6 +/- 1.7 mN m(-1)), at the oral surface of the soft palate (56.1 +/- 3.2 mN m(-1)) and from the posterior oro-pharyngeal wall (58.1 +/- 2.4 mN m(-1)). The pull-off force method provides adequate reproducibility to be able to measure the gamma of UAL. In healthy humans the gamma of UAL is similar to that of saliva.
Publisher: IOP Publishing
Date: 12-11-2014
DOI: 10.1088/0967-3334/35/12/2447
Abstract: Nasal expiratory resistive valves (Provent(®)) have been proposed as novel therapy for obstructive sleep apnea. We compared pressure measurements from a standard nasal pressure catheter used to assess nasal airflow during sleep with those from nasal expiratory resistive device with attached proprietary nasal pressure cannula. Nasal pressure cannula or Provent(®) + proprietary nasal pressure cannula were attached to a bench model of human anterior nares and nasal passages, and pressure measured (P). Respiratory airflows generated by a subject breathing were applied to rear of model and airflow (V) measured via pneumotachograph. Airflow litude (ΔV) was plotted against pressure litude (ΔP). Hypopnoea detection ( 0.65, p < 0.0001 p < 0.0001 for between slope difference). For nasal pressure cannula, specificity of hypopnoea detection differed between reference breaths one and two (80.2% and 40.0%, respectively), and Provent(®) + proprietary nasal pressure cannula (30.3% and 74.2%, respectively). Quantification of airflow obstruction in the presence of Provent(®) + proprietary nasal pressure cannula is greatly influenced by the reference breath chosen to determine a reduction in nasal airflow. Reported variability in therapeutic response to nasal expiratory resistive devices may relate to differences in measurement technique specificity used to quantify the severity of sleep disordered breathing.
Publisher: Springer Science and Business Media LLC
Date: 15-05-2021
Publisher: Oxford University Press (OUP)
Date: 07-2011
DOI: 10.5665/SLEEP.1134
Publisher: American Physiological Society
Date: 02-1999
DOI: 10.1152/JAPPL.1999.86.2.523
Abstract: The afferent pathways and upper airway receptor locations involved in negative upper airway pressure (NUAP) augmentation of soft palate muscle activity have not been defined. We studied the electromyographic (EMG) response to NUAP for the palatinus, tensor veli palatini, and levator veli palatini muscles in 11 adult, supine, tracheostomized, anesthetized dogs. NUAP was applied to the nasal or laryngeal end of the isolated upper airway in six dogs and to four to six serial upper airway sites from the nasal cavity to the subglottis in five dogs. When NUAP was applied at the larynx, peak inspiratory EMG activity for the palatinus and tensor increased significantly ( P 0.05) and plateaued at a NUAP of −10 cmH 2 O. Laryngeal NUAP failed to increase levator activity consistently. Nasal NUAP did not increase EMG activity for any muscle. Consistent NUAP reflex recruitment of soft palate muscle activity only occurred when the larynx was exposed to the stimulus and, furthermore, was abolished by bilateral section of the internal branches of the superior laryngeal nerves. We conclude that soft palate muscle activity may be selectively modulated by afferent activity originating in the laryngeal and hypopharyngeal airway.
Publisher: European Respiratory Society (ERS)
Date: 04-2008
DOI: 10.1183/09031936.00001007
Abstract: Factors influencing nasal versus oral breathing in asthmatics are not well understood. The current authors hypothesised that asthmatic subjects have enhanced perception of nasal threshold loads, and switch from nasal to oral breathing at a lower load than healthy subjects. In total, 15 mild asthmatic and 20 healthy control subjects breathed nasally via an inspiratory threshold loading device. Nasal loading was progressively increased until subjects switched to oral breathing. Load perception at switching was rated using a Borg scale. Nasal resistance was measured using posterior rhinomanometry. The protocol was repeated before and after nasal decongestant administration in subgroups of 10 healthy control and six asthmatic subjects. Inspiratory nasal resistance was within normal limits for most subjects and was not significantly different between asthmatics and healthy controls. Compared with controls, asthmatics switched to oral breathing at a significantly lower nasal load but rated "difficulty breathing in" at the same level. Decongestant significantly lowered nasal resistance but did not change the nasal load initiating switching in either subgroup. Enhanced perception of nasal loading may trigger increased oral breathing in asthmatics, potentially enhancing exposure to nonconditioned inhaled gas and contributing to the occurrence and/or severity of bronchoconstrictive exacerbations.
Publisher: American Physiological Society
Date: 04-2014
DOI: 10.1152/JAPPLPHYSIOL.01245.2013
Abstract: Caudal tracheal displacement (TD) leads to improvements in upper airway (UA) function and decreased collapsibility. To better understand the mechanisms underlying these changes, we examined effects of TD on peripharyngeal tissue stress distributions [i.e., extraluminal tissue pressure (ETP)], deformation of its topographical surface (UA lumen geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing, adult male New Zealand white rabbits. Graded TD was applied to the cranial tracheal segment from 0 to ∼10 mm. ETP was measured at six locations distributed around/along the length of the UA, covering three regions: tongue, hyoid, and epiglottis. Axial images of the UA (nasal choanae to glottis) were acquired with computed tomography and used to measure lumen geometry (UA length regional cross-sectional area) and hyoid bone displacement. TD resulted in nonuniform decreases in ETP (generally greatest at tongue region), ranging from −0.07 (−0.11 to −0.03) [linear mixed-effects model slope (95% confidence interval)] to −0.27 (−0.31 to −0.23) cmH 2 O/mm TD, across all sites. UA length increased by 1.6 (1.5–1.8)%/mm, accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 2.8 (1.7–3.9) to 4.9 (3.8–6.0)%/mm. The hyoid bone was displaced caudally by 0.22 (0.18–0.25) mm/mm TD. In summary, TD imposes a load on the UA that results in heterogeneous changes in peripharyngeal tissue stress distributions and resultant lumen geometry. The hyoid bone may play a pivotal role in redistributing applied caudal tracheal loads, thus modifying tissue deformation distributions and determining resultant UA geometry outcomes.
Publisher: European Respiratory Society (ERS)
Date: 07-2004
DOI: 10.1183/09031936.04.00004303
Abstract: Breathing route during sleep has been studied very little, however, it has potential importance in the pathophysiology of sleep disordered breathing. Using overnight polysomnography, with separate nasal and oral thermocouple probes, data were obtained from 41 subjects (snorers and nonsnorers 25 male and 16 female aged 20-66 yrs). Awake, upright, inspiratory nasal resistance (Rn) was measured using posterior rhinomanometry. Each 30-s sleep epoch (not affected by apnoeas/hypopnoeas) was scored for presence of nasal and/or oral breathing. Overnight, seven subjects breathed nasally, one subject oro-nasally and the remainder switched between nasal and oro-nasal breathing. Oral-only breathing rarely occurred. Nasal breathing epochs were 55.79 (69.78) per cent of total sleep epochs (%TSE median (interquartile range)), a value not significantly different to that for oro-nasal (TSE: 44.21 (68.66)%). Oro-nasal breathing was not related to snoring, sleep stage, posture, body mass index, height, weight, Rn (2.19 (1.77) cm H2O x L(-1) x sec(-1)) or sex, but was positively associated with age. Subjects > or = 40 yrs were approximately six times more likely than younger subjects to spend >50% of sleep epochs utilising oro-nasal breathing. Ageing is associated with an increasing occurrence of oro-nasal breathing during sleep.
Publisher: Oxford University Press (OUP)
Date: 09-2014
DOI: 10.5665/SLEEP.3996
Publisher: Wiley
Date: 11-2017
DOI: 10.5694/MJA17.00684
Publisher: Canadian Science Publishing
Date: 12-1999
DOI: 10.1139/H99-035
Abstract: The external nasal dilator strip (ENDS) device (Breathe Right®, CNS Inc., Chanhassen, MN, USA) has been adopted by athletes to promote nasal route breathing during exercise. We studied the influence of ENDS on the switching point from nasal-only to oro-nasal breathing during exercise in 4 healthy men (age 25 ± 2 yrs, mean ± SEM) and 5 women (age 30 ± 5 yrs). Resting inspiratory nasal airflow resistance decreased from 0.33 ± 0.02 kPa/L/s without ENDS to 0.22 ± 0.01 kPa/L/s with ENDS (p 0.01). ENDS delayed the onset of oro-nasal breathing such that the time from commencement of exercise to switching increased by 15.2%, and maximum levels of inspiratory nasal airflow and ventilation achieved prior to switching increased by 14.9% and 14.3%, respectively (all p 0.05). We conclude that, in normal healthy subjects, ENDS does promote nasal route breathing during exercise, but any delay in the onset of oral route breathing during a progressive exercise task appears relatively small. Key words: upper airway, nose, mouth breathing
Publisher: American Physiological Society
Date: 1997
DOI: 10.1152/JAPPL.1997.82.1.78
Abstract: Van der Touw, T., A. B. H. Crawford, and J. R. Wheatley.Effects of a synthetic lung surfactant on pharyngeal patency in awake human subjects. J. Appl. Physiol. 82(1): 78–85, 1997.—We examined the effects of separate applications of saline and a synthetic lung surfactant preparation (Surf Exosurf Neonatal) into the supraglottic airway (SA) on the anteroposterior pharyngeal diameter ( D ap ) and the airway pressures required to close (Pcl) and reopen (Pop) the SA in five awake normal supine subjects. D ap , Pcl, and Pop were determined during lateral X-ray fluoroscopy and voluntary glottic closure when pressure applied to the SA lumen was decreased from 0 to −20 cmH 2 O and then increased to +20 cmH 2 O. After Surf application and relative to control, D ap was larger for most of the applied pressures, Pcl decreased (−12.3 ± 1.9 to −18.7 ± 0.9 cmH 2 O P 0.01), Pop decreased (13.4 ± 1.9 to −6.0 ± 3.4 cmH 2 O P 0.01), and genioglossus electromyographic activity did not change ( P 0.05). Saline had no effect. These observations suggest that pharyngeal intraluminal surface properties are important in maintaining pharyngeal patency. We propose that surfactants enhance pharyngeal patency by reducing surface tension and adhesive forces acting on intraluminal SA surfaces.
Publisher: Elsevier BV
Date: 03-2012
Publisher: American Physiological Society
Date: 10-2003
DOI: 10.1152/JAPPLPHYSIOL.00432.2003
Abstract: Transmural pressure at any level in the upper airway is dependent on the difference between intraluminal airway and extraluminal tissue pressure (ETP). We hypothesized that ETP would be influenced by topography, head and neck position, resistive loading, and stimulated breathing. Twenty-eight male, New Zealand White, anesthetized, spontaneously breathing rabbits breathed via a face mask with attached pneumotachograph to measure airflow and pressure transducer to monitor mask pressure. Tidal volume was measured via integration of the airflow signal. ETP was measured with a pressure transducer-tipped catheter inserted in the tissues of the lateral (ETPlat, n = 28) and anterior (ETPant, n = 21) pharyngeal wall. Head position was controlled at 30, 50, or 70°, and the effect of addition of an external resistor, brief occlusion, or stimulated breathing was examined. Mean ETPlat was ∼0.7 cmH 2 O greater than mean ETPant when adjusted for degree of head and neck flexion ( P 0.05). Mean, maximum, and minimum ETP values increased significantly by 0.7-0.8 cmH 2 O/20° of head and neck flexion when adjusted for site of measurement ( P 0.0001). The main effect of resistive loading and occlusion was an increase in the change in ETPlat (maximum - minimum ETPlat) and change in ETPant at all head and neck positions ( P 0.05). Mean ETPlat and ETPant increased with increasing tidal volume at head and neck position of 30° (all P 0.05). In conclusion, ETP was nonhomogeneously distributed around the upper airway and increased with both increasing head and neck flexion and increasing tidal volume. Brief airway occlusion increased the size of respiratory-related ETP fluctuations in upper airway ETP.
Publisher: Oxford University Press (OUP)
Date: 04-2005
Abstract: The obstructive sleep apnea hypopnea syndrome (OSAHS) is a disorder characterized by repetitive closure and reopening of the upper airway during sleep. Upper airway luminal patency is influenced by the surface tension (gamma) acting within the liquid layer lining the upper airway. The aim of the present study was to examine the gamma of upper airway mucosal lining liquid (UAL) in both healthy subjects and patients with OSAHS before and after sleep. Measurements were performed before (PM) and after (AM) an overnight polysomnographic study. Sleep laboratory. We studied 11 healthy adults (5 men, 6 women) and 15 patients with OSAHS (14 men, 1 woman). None. The gamma of UAL ("pull-off' force technique, pooled PM and AM s les) in patients with OSAHS was increased (59.9 [53.8, 58.8] mN/m mean [95% confidence interval]) compared with healthy subjects (56.3 [57.7, 62.1] mN/m linear mixed effects models P =.05). In both groups there was no significant difference between PM (56.6 [53.7, 59.5] mN/m for healthy subjects, 60.1 [57.9, 62.3] mN/m for the patients with OSAHS) and AM (56.1 [51.8, 60.4] mN/m and 59.6 [57.4, 61.8] mN/m, respectively) s les for gamma of UAL and salivary flow rate (5 minutes unstimulated collection PM =0.53 [0.22, 0.84] mL/minute for healthy subjects, 0.38 [0.22, 0.54] mL/minute for OSAHS AM=0.39 [0.23, 0.55] mL/minute and 0.32 [0.2, 0.44] mL/minute). However, the occurrence of nasal breathing during sleep was associated with a fall in gamma of UAL overnight (r2 = 0.15, P < .05). Patients with OSAHS have normal salivary flow rate but an increased gamma of UAL. In both healthy subjects and OSAHS patients, nasal breathing during sleep was associated with an overnight fall in the gamma of UAL.
Publisher: American Physiological Society
Date: 11-2010
DOI: 10.1152/JAPPLPHYSIOL.00096.2010
Abstract: We studied the impact of wall strain and surrounding pressure on the onset of airflow limitation in a thin-walled “floppy” tube model. A vacuum source-generated steady-state (baseline) airflow (0–350 ml/s) through a thin-walled latex tube (length 80 mm, wall thickness 0.23 mm) enclosed within a rigid, sealed, air-filled, cylindrical chamber while upstream minus downstream pressure, chamber pressure (Pc), and lumen geometry [in-line digital camera segmentation (Amira 5.2.2) and analysis (Rhinoceros 4) software] were monitored. Longitudinal strain (S 0–62.5%) and Pc (0–20 cmH 2 O) combinations were imposed, and Pc associated with onset of 1) reduced airflow and 2) fully developed airflow limitation recorded. At any strain, increasing Pc resulted in a decrease in airflow. Across all baseline airflow, threshold pressure was 1–7 cmH 2 O for S 25%, 6–8 cmH 2 O at S = 25% and 37.5%, and 5–7 cmH 2 O at S = 50% and 62.5%. Pc associated with fully developed airflow limitation was 4–6 cmH 2 O for S 25%, cmH 2 O at S = 25% (i.e., no flow limitation), 18 cmH 2 O at S = 37.5%, and 8–12 cmH 2 O at S = 50% and 62.5%. Lumen area decreased with increasing Pc but was 1) larger at S = 25% and 2) characterized by bifold narrowing at S 25% and trifold narrowing at S ≥ 25%. In conclusion, tube function was modulated by Pc vs. S interactions, with S = 25% producing trifold lumen narrowing, maximal patency, and no airflow limitation. Findings may have implications for understanding peripharyngeal tissue pressure and pharyngeal wall strain effects on passive pharyngeal airway function in humans.
Publisher: Informa UK Limited
Date: 29-11-2017
DOI: 10.1080/09286586.2017.1409360
Abstract: To assess the effect of pupil dilation on measures of retinal vessel caliber. Observational study with self-comparisons Methods: Retinal photographs were taken for both eyes of 25 subjects before and after pupil dilation. Three photographic graders, masked to pupil dilation status, measured the same set of images using a computer-assisted, semi-automatic method. We compared means (standard deviations) of retinal arteriolar caliber equivalent (CRAE) and retinal venular caliber equivalent (CRVE) of the same eyes between pre- and post-dilation images. We assessed concordance correlation coefficients (CC), Bland Altman limits-of-agreements, and used linear mixed models to assess CRAE and CRVE measures associated with pupil dilation (influencing image quality), graders (observers) and right-left eye variation. We found high CCs for CRAE (0.82-0.94) and CRVE (0.87-0.94) between pre- and post-dilation images of the same eyes across the graders. Bland Altman plots showed that mean differences ranged from 0.55-3.42μm for CRAE and 1.56-2.29μm for CRVE. After adjusting for right-left eye random variation, a significant fixed effect of dilation was evident in mean CRAE in two of the three graders. There was no significant fixed effect of dilation in mean CRVE across all graders. In models including data of both eyes' measures from pre- and post-dilation images by three graders, the fixed effect for dilation status contributed significantly to CRAE and CRVE variances whereas random effects for graders and dilation status contributed minimally. Contrary to our hypothesis, we found a systematic effect of pupil dilation on retinal vessel caliber measures.
Publisher: Elsevier BV
Date: 11-2019
Publisher: European Respiratory Society (ERS)
Date: 05-2000
DOI: 10.1034/J.1399-3003.2000.15E20.X
Abstract: The adhesive external nasal dilator strip (ENDS) is widely advocated for prevention of snoring and promotion of nasal breathing during exercise. In the present study, the effects of the ENDS on nasal airflow resistance (Rn) in normal subjects were examined and factors determining in idual responses to the ENDS explored. Using posterior rhinomanometry, 20 healthy Caucasian adults (10 males, 10 females age: 18-56 yrs) were studied during quiet tidal breathing and voluntary hyperpnoea with (ENDS) and without (control) ENDS and with a placebo strip (placebo) before and after application of a topical nasal decongestant (oxymetazoline hydrochloride). During tidal breathing, only nine subjects showed a significantly (p<0.05) decreased inspiratory and/or expiratory Rn with the ENDS ("responders"). During the control, inspiratory Rn (at 0.4 L x s(-1)) was higher in "responders" than "nonresponders" (3.28+/-0.16 versus 2.60+/-0.08 cmH2O x L(-1) x s p=0.04). The effects of nasal decongestant and the ENDS were additive. During voluntary hyperpnoea, inspiratory Rn (at 1.0 L x s(-1)) and the hysteresis of the inspiratory transnasal pressure/flow curve were decreased with the ENDS in most subjects. It is concluded that the external nasal dilator strip influences nasal airflow dynamics by both dilation of the nasal valve and stabilization of the lateral nasal vestibule walls and may be more effective in subjects with a high resting nasal airflow resistance.
Publisher: American Physiological Society
Date: 03-2009
DOI: 10.1152/JAPPLPHYSIOL.91236.2008
Abstract: Lateral pharyngeal fat pad compression of the upper airway (UA) wall is thought to influence UA size in patients with obstructive sleep apnea. We examined interactions between acute mass/volume loading of the UA extra-luminal tissue space and UA patency. We studied 12 supine, anesthetized, spontaneously breathing, head position-controlled (50°), New Zealand White rabbits. Submucosal extraluminal tissue pressures (ETP) in the anterolateral (ETPlat) and anterior (ETPant) pharyngeal wall were monitored with surgically inserted pressure transducer-tipped catheters (Millar). Tracheal pressure (Ptr) and airflow (V̇) were measured via a pneumotachograph and pressure transducer inserted in series into the intact trachea, with hypopharyngeal cross-sectional area (CSA) measured via computed tomography, while graded saline inflation (0–1.5ml) of a compliant tissue expander balloon in the anterolateral subcutaneous tissue was performed. Inspiratory UA resistance (Rua) at 20 ml/s was calculated from a power function fitted to Ptr vs. V̇ data. Graded expansion of the anterolateral balloon increased ETPlat from 2.3 ± 0.5 cmH 2 O ( n = 11, mean ± SEM) to 5.0 ± 1.1 cmH 2 O at 1.5-ml inflation ( P 0.05 ANOVA). However, ETPant was unchanged from 0.5 ± 0.5 cmH 2 O ( n = 9 P = 0.17). Concurrently, Rua increased to 119 ± 4.2% of baseline value ( n = 12 P 0.001) associated with a significant reduction in CSA between 10 and 70% of airway length to a minimum of 82.2 ± 4.4% of baseline CSA at 40% of airway length ( P 0.05). We conclude that anterolateral loading of the upper airway extraluminal tissue space decreases upper airway patency via an increase in ETPlat, but not ETPant. Lateral pharyngeal fat pad size may influence UA patency via increased tissue volume and pressure causing UA wall compression.
Publisher: American Physiological Society
Date: 11-2007
DOI: 10.1152/JAPPLPHYSIOL.01413.2006
Abstract: Snoring-associated vibration energy transmission from the upper airway to the carotid artery has been hypothesized as a potential atherosclerotic plaque initiating/rupturing event that may provide a pathogenic mechanism linking snoring and embolic stroke. We examined transmission of oscillatory pressure waves from the pharyngeal lumen to the common carotid artery wall and lumen in seven male, anesthetized, spontaneously breathing New Zealand White rabbits. Airflow was monitored via a pneumotachograph inserted in series in the intact trachea. Fifteen 20-s runs of, separately, 40-, 60-, and 90-Hz oscillatory pressure waves [pressure litude in the trachea (Ptr ), litude 2–20 cmH 2 O] were generated by a loudspeaker driven by a sine wave generator and lifier and superimposed on tidal breathing via the cranial tracheal connector. Pressure transducer-tipped catheters measured pressure litudes in the tissues adjacent to the common carotid artery bifurcation (Pcti ) and within the lumen (carotid sinus Pcs ). Data were analyzed using power spectrum analysis and linear mixed-effects statistical modeling. Both the frequency (f) and litude of the injected pressure wave influenced Pcti and Pcs , in that ln Pcti = 1.2(Ptr ) + 0.02(f) − 5.2, and ln Pcs = 0.6(Ptr ) + 0.02(f) − 4.9 (both P 0.05). Across all frequencies tested, transfer of oscillatory pressure across the carotid artery wall was associated with an litude gain, as expressed by a Pcs -to-Pcti ratio of 1.8 ± 0.3 ( n = 6). Our findings confirm transmission of oscillatory pressure waves from the upper airway lumen to the peripharyngeal tissues and across the carotid artery wall to the lumen. Further studies are required to establish the role of this incident energy in the pathogenesis of carotid artery vascular disease.
Publisher: BMJ
Date: 05-1999
DOI: 10.1136/THX.54.5.423
Abstract: Patients with obstructive sleep apnoea (OSA) have a number of upper airway structural abnormalities which may influence the resistance of the oral airway to airflow. There have been no systematic studies of the flow dynamics of the oral cavity in such patients. Inspiratory oral airway resistance to airflow (RO) was measured in 13 awake patients with OSA in both the upright and supine positions (neck position constant). Each subject breathed via a mouthpiece while the nasal airway was occluded with a nasal mask. In the upright position the mean (SE) RO was 1.26 (0. 19) cm H2O/l/s (at 0.4 l/s) which increased to 2.01 (0.43) cm H2O/l/s when supine (p<0.05, paired t test). The magnitude of this change correlated negatively with the respiratory disturbance index (r = -0.60, p = 0.03). In awake patients with OSA RO is normal when upright but abnormally raised when in the supine position.
Publisher: Elsevier BV
Date: 02-2013
Publisher: American Physiological Society
Date: 04-2016
DOI: 10.1152/JAPPLPHYSIOL.00820.2015
Abstract: The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for in idually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics.
Publisher: Informa UK Limited
Date: 04-2017
DOI: 10.2147/COPD.S131778
Publisher: Wiley
Date: 04-1996
DOI: 10.1111/J.1445-5994.1996.TB00889.X
Abstract: Ly6c is an antigen commonly used to differentiate between classical and non-classical monocytes/macrophages. Here we show its potential as a marker of the mouse vasculature, particularly of the retinal vascular plexuses. Ly6c was immunodetected in several tissues of C57BL/6 mice using isolectin IB4 as the control of vasculature staining. In the retina, Ly6c expression was analyzed qualitatively and quantitatively in intact, ischemic, and contralateral retinas from 0 to 30 days after the insult. Ly6c expression was observed in all organs and tissues tested, with a brighter signal and more homogeneous staining than the IB4. In the retinas, Ly6c was well expressed, allowing a detailed study of their anatomy. The three retinal plexuses were morphologically different, and from the superficial to the deep one occupied 15 ± 2, 24 ± 7, and 38 ± 1.4 percent of the retinal surface, respectively. In the injured retinas, there was extravasation of the classically activated monocyte/macrophages (Ly6c
Publisher: American Physiological Society
Date: 07-2003
DOI: 10.1152/JAPPLPHYSIOL.01198.2002
Abstract: Upper airway (UA) patency may be influenced by surface tension (γ) operating within the (UAL). We examined the role of γ of UAL in the maintenance of UA patency in eight isoflurane-anesthetized supine human subjects breathing via a nasal mask connected to a pneumotachograph attached to a pressure delivery system. We evaluated 1) mask pressure at which the UA closed (Pcrit), 2) UA resistance upstream from the site of UA collapse (RUS), and 3) mask pressure at which the UA reopened (Po). A multiple pressure-transducer catheter was used to identify the site of airway closure (velopharyngeal in all subjects). UAL s les (0.2 μl) were collected, and the γ of UAL was determined by using the “pull-off force” technique. Studies were performed before and after the intrapharyngeal instillation of 5 ml of exogenous surfactant (Exosurf, Glaxo Smith Kline). The γ of UAL decreased from 61.9 ± 4.1 (control) to 50.3 ± 5.0 mN/m (surfactant P 0.02). Changes in Po, RUS, and Po - Pcrit (change = control - surfactant) were positively correlated with changes in γ ( r 2 0.6 P 0.02) but not with changes in Pcrit ( r 2 = 0.4 P 0.9). In addition, mean peak inspiratory airflow (no flow limitation) significantly increased ( P 0.04) from 0.31 ± 0.06 (control) to 0.36 ± 0.06 l/s (surfactant). These findings suggest that γ of UAL exerts a force on the UA wall that hinders airway opening. Instillation of exogenous surfactant into the UA lowers the γ of UAL, thus increasing UA patency and augmenting reopening of the collapsed airway.
Publisher: American Physiological Society
Date: 05-1999
DOI: 10.1152/JAPPL.1999.86.5.1638
Abstract: We studied the effect of an adhesive external nasal dilator strip (ENDS) on external nasal geometry in 20 healthy Caucasian adults (10 men, 10 women age 21–45 yr). The recoil force exerted by ENDS was estimated by bending the device ( n = 10) with known weights. In the horizontal direction, a small/medium-sized ENDS in situ exerted a unilateral recoil force of 21.4–22.6 g. Application of ENDS resulted in a displacement of the lateral nasal vestibule walls that had both anterosuperior and horizontal components and that was maintained over an 8-h period. The resultant unilateral nasal vestibule wall displacement at the tip of the device was at 47.6 ± 2.0° to the horizontal (as related to the plane of the device when in situ) and had a magnitude of 3.5 ± 0.1 mm. ENDS increased external nasal cross-sectional area by 23.0–65.3 mm 2 . Nasal vestibule wall compliance was estimated at 0.05–0.16 mm/g. Thus ENDS applies a relatively constant abducting force irrespective of nasal width. Variable responsiveness to ENDS may be related to differences in elastic properties of the nasal vestibule wall.
Publisher: Oxford University Press (OUP)
Date: 11-2011
DOI: 10.5665/SLEEP.1380
Publisher: American Physiological Society
Date: 04-1999
DOI: 10.1152/JAPPL.1999.86.4.1396
Abstract: We examined whether receptors in the tongue muscle respond to negative upper airway pressure (NUAP). In six cats, one hypoglossal nerve was cut and its distal end was prepared for single-fiber recording. Twelve afferent fibers were selected for study on the basis of their sensitivity to passive stretch (PS) of the tongue. Fiber discharge frequency was measured during PS of the tongue and after the rapid onset of constant NUAP. During PS of 1–3 cm, firing frequency increased from 17 ± 7 to 40 ± 11 (SE) Hz ( P 0.01). In addition, 8 of the 12 fibers responded to NUAP (−10 to −30 cmH 2 O), with firing frequency increasing from 23 ± 9 to 41 ± 9 Hz ( P 0.001). In two fibers tested, the increase in firing frequency in response to NUAP was not altered by topical anesthesia (10% lignocaine) applied liberally to the entire upper airway mucosa. Our results demonstrate that afferent discharges from the hypoglossal nerve are elicited by 1) stretching of the tongue and 2) NUAP before and after upper airway anesthesia. We speculate that activation of proprioceptive mechanoreceptors in the cat’s tongue provides an additional pathway for the reflex activation of upper airway dilator muscles in response to NUAP, independent of superficially located mucosal mechanoreceptors.
Publisher: American Thoracic Society
Date: 15-11-2003
Publisher: Wiley
Date: 15-11-2008
Publisher: Wiley
Date: 21-05-2008
DOI: 10.1111/J.1440-1843.2008.01300.X
Abstract: Nasal breathing provides a protective influence against exercise-induced asthma. We hypothesized that enforced oral breathing in resting mild asthmatic subjects may lead to a reduction in lung function. Asymptomatic resting mild asthmatic volunteers (n = 8) were instructed to breathe either nasally only (N tape over lips) or orally only (O nose clip) for 1 h each, on separate days. Lung function (% predicted FEV(1)) was measured using standard spirometry at baseline and every 10 min for 1 h. 'Difficulty in breathing' was rated using a Borg scale at the conclusion of the N and O periods. Baseline FEV(1) on the N (101.2 +/- 3.8% predicted) and O (102.7 +/- 3.9% predicted) days was not significantly different (P > 0.3). At 60 min, FEV(1) on the O day (96.5 +/- 4.1% predicted) was significantly less than on the N day (101.0 +/- 3.5% predicted P 0.3), whereas on the O day, FEV(1) fell progressively (slope = -0.06 +/- 0.01% FEV(1)/min, P < 0.0001 linear mixed effects modelling). Three subjects experienced coughing/wheezing at the end of the O day but none experienced symptoms at the end of the N day. Subjects perceived more 'difficulty breathing in' at the end of the O day (1.5 +/- 0.4 arbitrary units) than on the N day (0.4 +/- 0.3 arbitrary unit P < 0.05). Enforced oral breathing causes a decrease in lung function in mild asthmatic subjects at rest, initiating asthma symptoms in some. Oral breathing may play a role in the pathogenesis of acute asthma exacerbations.
Publisher: Wiley
Date: 10-1998
DOI: 10.1111/J.1469-7793.1998.307BF.X
Abstract: 1. Using X-ray fluoroscopy we measured antero-posterior (A-P) and cranio-caudal (C-C) displacements of the epiglottic tip (ET), corniculate cartilage and hyoid bone in seven seated, normal human subjects (age 34 +/- 3 years mean +/- S.E.M. 4 males, 3 females) breathing via a nasal mask or mouthpiece with (RL) and without (UB) a fixed resistive load. 2. During UB, via either mouth or nose, there were no significant A-P ET movements. During RL via the nose the ET at peak expiratory flow was 2.6 +/- 1.3 mm cranial to its position at peak inspiratory flow (P < 0.05, ANOVA). C-C movements of the ET correlated strongly with C-C movements of the corniculate cartilage and hyoid bone. 3. The ET, corniculate cartilage and hyoid bone (at zero airflow) were situated more caudally during oral UB than for any other condition. 4. When present, epiglottic movements during breathing do not appear to be independent of those of the larynx and hyoid. Furthermore, epiglottic position may be related to the level of upper airway resistance.
Publisher: Elsevier BV
Date: 12-2000
Publisher: Wiley
Date: 21-07-2006
Publisher: American Physiological Society
Date: 04-2012
DOI: 10.1152/JAPPLPHYSIOL.01286.2011
Abstract: Increasing lung volume improves upper airway airflow dynamics via passive mechanisms such as reducing upper airway extraluminal tissue pressures (ETP) and increasing longitudinal tension via tracheal displacement. We hypothesized a threshold lung volume for optimal mechanical effects on upper airway airflow dynamics. Seven supine, anesthetized, spontaneously breathing New Zealand White rabbits were studied. Extrathoracic pressure was altered, and lung volume change, airflow, pharyngeal pressure, ETP laterally (ETPlat) and anteriorly (ETPant), tracheal displacement, and sternohyoid muscle activity (EMG%max) monitored. Airflow dynamics were quantified via peak inspiratory airflow, flow limitation upper airway resistance, and conductance. Every 10-ml lung volume increase resulted in caudal tracheal displacement of 2.1 ± 0.4 mm (mean ± SE), decreased ETPlat by 0.7 ± 0.3 cmH 2 O, increased peak inspiratory airflow of 22.8 ± 2.6% baseline (all P 0.02), and no significant change in ETPant or EMG%max. Flow limitation was present in most rabbits at baseline, and abolished 15.7 ± 10.5 ml above baseline. Every 10-ml lung volume decrease resulted in cranial tracheal displacement of 2.6 ± 0.4 mm, increased ETPant by 0.9 ± 0.2 cmH 2 O, ETPlat was unchanged, increased EMG%max of 11.1 ± 0.3%, and a reduction in peak inspiratory airflow of 10.8 ± 1.0%baseline (all P 0.01). Lung volume, resistance, and conductance relationships were described by exponential functions. In conclusion, increasing lung volume displaced the trachea caudally, reduced ETP, abolished flow limitation, but had little effect on resistance or conductance, whereas decreasing lung volume resulted in cranial tracheal displacement, increased ETP and increased resistance, and reduced conductance, and flow limitation persisted despite increased muscle activity. We conclude that there is a threshold for lung volume influences on upper airway airflow dynamics.
Publisher: Wiley
Date: 12-08-2015
DOI: 10.1111/JSR.12205
Abstract: Obstructive sleep apnea (OSA) is more common in men than women. Body size is greater in males (sexual dimorphism), but large body habitus is associated with OSA for both genders. We speculated that male-female phenotypical convergence (reduced sexual dimorphism via identical phenotype acquisition) occurs with OSA and tested hypotheses: (1) phenotypical features pathogenic for OSA differ between OSA and healthy subjects irrespective of gender and (2) such characteristics exhibit phenotypical convergence. Utilizing an existing database, we calculated male-female (group average) ratios for eight anthropometric and 33 surface cephalometric variables from 104 Caucasian OSA patients [72 males apnea-hypopnea index (events h(-1) ): males: 42.3 ± 24.7 versus females: 42.6 ± 26.1 (P > 0.9)] and 85 Caucasian, healthy, non-OSA, community volunteers (36 males). Log-transformed data were analysed using a general linear model with post-hoc unpaired t-tests and significance at P 1.0 across groups, but with no significant group × gender interactions no variable satisfied hypothesis (2). Thus, in this exploratory study, OSA patients had gender-common phenotypical differences to healthy subjects, but sexual dimorphism was preserved. Lack of complete phenotypical convergence may indicate gender-based critical phenotype-level attainment for OSA and/or gender-based OSA prevalence arises from factors other than those in this study.
Publisher: Wiley
Date: 12-1999
DOI: 10.1046/J.1440-1843.1999.00201.X
Abstract: The ventilatory response to hypercapnia is greater breathing orally than nasally. We hypothesize that this is due to higher nasal resistance to airflow compared with oral resistance. Seven normal male subjects were studied during both progressive hyperoxic hypercapnia (HC) and exercise (EX) until ventilation exceeded 40 L/min. Under each condition, subjects breathed via the nose only or the mouth only. For each breathing route, ventilation and pathway resistance were calculated simultaneously at the highest common exercise workload (140 +/- 20 watt mean +/- SE) or the same end-tidal CO2 level (8.0 +/- 0.5%). The ventilatory response breathing nasally was decreased by a similar amount for both EX and HC when compared with the oral route. The difference between nasal and oral ventilation was highly correlated with the difference between nasal resistance and oral resistance for both EX and HC (linear regression analysis r = 0.91 for EX and r = 0.86 for HC both P < 0.01). We conclude that the breathing route dependence of ventilatory responses to respiratory stimuli in normal subjects is independent of the method of stimulation and is substantially determined by the added resistance of nasal breathing.
Publisher: Wiley
Date: 02-1999
DOI: 10.1111/J.1469-7793.1999.293AD.X
Abstract: 1. Oral airway resistance (RO) is an important determinant of oro-nasal partitioning of airflow (e.g. during exercise and sleep) however, little is known of factors influencing its magnitude and measurement. 2. We developed a non-invasive standardized technique for measuring RO (based on a modification of posterior rhinomanometry) and examined inspiratory RO in 17 healthy male subjects (age, 36 +/- 2 years (mean +/- s.e.m.) height, 177 +/- 2 cm weight, 83 +/- 3 kg). 3. Inspiratory RO (at 0.4 l s-1) was 0.86 +/- 0.23 cmH2O l-1 s-1 during resting mouthpiece breathing in the upright posture. RO was unaffected by assumption of the supine posture, tended to decrease with head and neck extension and increased to 1.22 +/- 0.19 cmH2O l-1 s-1 (n = 10 subjects, P < 0.01) with 40-45 deg of head and neck flexion. When breathing via a mouth-mask RO was 2.98 +/- 0.42 cmH2O l-1 s-1 (n = 7) and not significantly different from nasal airway resistance. 4. Thus, in awake healthy male subjects with constant jaw position, RO is unaffected by body posture but increases with modest degrees of head and neck flexion. This influence on upper airway patency may be important when oral route breathing is associated with alterations in head and neck position, e.g. during sleep.
Publisher: European Respiratory Society (ERS)
Date: 02-2001
DOI: 10.1183/09031936.01.17201950
Abstract: Aerosolized hypertonic saline is currently being investigated as a new agent for the treatment of impaired mucociliary clearance which occurs in many respiratory diseases. Mannitol aerosols, in particular dry powder inhalers, have been proposed as an alternative treatment to saline, offering the same osmotic load with other benefits. However, the effects of these hypertonic aerosols on airway epithelial ion transport processes have not been tested in human subjects in vivo . This report examines the effect of these solutions on airway ion transport using the nasal potential difference (PD) technique. Seven healthy nonsmoking adult volunteers were studied. On different days, a dose-response curve was constructed for the saline added to Krebs N-[2-hydroxyethyl] piperazine-N′-[2-ethanesulphonic acid] (HEPES) diluent. The reversibility of this saline effect was measured, and the response to additional saline (500 mM) and mannitol (1 M) compared. Hypertonic saline decreased nasal PD in a dose-related manner, with mean (sem) decreases in PD (less negative) of 6.6 (1.5), 7.6 (1.6), 10.0 (2.0), 13.1 (2.9) and 14.8 (3.2) mV (n=4) for addition of 150 mM, 250 mM, 500 mM, 1,200 mM and 2,000 mM NaCl to the Krebs HEPES diluent, respectively. The effect of hypertonic saline was fully reversible with washout for 3 min (presaline 15.9 (0.5) mV, postwashout 15.8 (1.1) mV, (n=4)). The hypertonic saline response was rapid in onset, sustained for at least 4 min, and decreased PD from 13.7 (1.7) mV to 5.1 (1.3) mV (n=7, p .001). In contrast, addition of mannitol to the perfusate did not significantly alter nasal PD, with a nonsignificant trend towards an increase (more negative) in the PD, (premannitol 13.9 (1.6) mV, postmannitol 15.3 (2.0) mV, n=7). As the osmotic stimulus of the 1 M mannitol is similar to that of the 500 mM sodium chloride, the ergent nasal potential difference responses suggest that the response to the saline was specific to the sodium chloride itself and not the simultaneous change in osmolarity. This demonstrates that the human airway epithelium in vivo can respond to topical hypertonic saline independent of the altered osmolarity.
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.RESP.2009.02.009
Abstract: We examined the influence of pharyngeal dilator muscle activity on upper airway extraluminal tissue pressure (ETP) distribution and upper airway patency. We studied seven anaesthetised, supine, spontaneously breathing NZ white rabbits. ETP was measured via pressure transducer tipped catheters in lateral (ETP(lat)) and anterior (ETP(ant)) pharyngeal wall tissues. Airflow (V) and tracheal pressure (P) were monitored and upper airway resistance (RUA) calculated. Genioglossus (GG) or bilateral sternohyoid (SH) muscles were electrically stimulated. Tongue protrusion (TP) during GG stimulation was measured. With GG stimulation, RUA decreased to 57.8+/-10.9% (mean+/-S.E.M.) of baseline and TP increased to 4.8+/-0.5mm (both p<0.05), but ETP(lat) (2.6+/-1.5 cm H(2)O) and ETP(ant) (1.4+/-0.8 cm H(2)O) were unchanged. SH stimulation reduced RUA to 53.6+/-6.8%, and ETP(lat) fell by 1.0+/-0.4 cm H(2)O (both p<0.05). ETP(ant) was unchanged. GG muscle contraction decreased RUA without altering ETP, whereas SH contraction altered RUA and ETP(lat), but not ETP(ant). Contraction of the upper airway dilator muscles results in improvements in upper airway patency associated with changes in peri-pharyngeal tissue pressure.
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