ORCID Profile
0000-0001-9641-3691
Current Organisation
University Hospital of Bern
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Cold Spring Harbor Laboratory
Date: 08-02-2021
DOI: 10.1101/2021.02.06.21251250
Abstract: Nitrogen multiple-breath washout (N 2 MBW) is an established technique to assess functional residual capacity (FRC) and ventilation inhomogeneity in the lung. Accurate measurement of gas concentrations is essential for the appropriate calculation of clinical outcomes. We investigated the accuracy of oxygen and carbon dioxide measurements used for the indirect calculation of nitrogen concentration in a commercial MBW device (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and its impact on FRC and lung clearance index (LCI). High precision calibration gas mixtures and mass spectrometry were used to evaluate sensor output. We assessed the impact of corrected signal processing on FRC and LCI in a dataset of healthy children and children with cystic fibrosis using custom analysis software. We found inadequate correction for the cross sensitivity of the oxygen and carbon dioxide sensors in the Exhalyzer D device. This results in an overestimation of expired nitrogen concentration, and consequently FRC and LCI outcomes. Breath-by-breath correction of this error reduced mean (SD) FRC by 8.9 (2.2)% and LCI by 11.9 (4.0)%. It also resulted in almost complete disappearance of the tissue nitrogen signal at the end of measurements. Inadequate correction for cross sensitivity between the oxygen and carbon dioxide gas sensors of the Exhalyzer D device leads to an overestimation of FRC and LCI. Correction of this error is possible and could be applied by re-analysing the measurements breath-by-breath in an updated software version. Eco Medics AG (Duernten, Switzerland) provided a research version of their commercial software Spiroware 3.2.1 including insight on signal processing algorithms and helped with the acquisition of mass spectrometry measurements. This project was funded by the Swiss National Science Foundation, Grant Nr. 182719 (P. Latzin) and 168173 (K. Ramsey)
Publisher: Cold Spring Harbor Laboratory
Date: 28-01-2022
DOI: 10.1101/2022.01.27.22269250
Abstract: Multiple-breath nitrogen washout is an established and sensitive technique to assess functional residual capacity and ventilation inhomogeneity in the lung. Indirect calculation of nitrogen concentration requires precise calibration and accurate measurement of gas concentrations. We investigated the accuracy of the carbon dioxide gas concentration used for the indirect calculation of nitrogen concentration in a commercial multiple-breath washout (MBW) device (EasyOne Pro LAB, ndd Medizintechnik AG, Zurich, Switzerland) and its impact on outcomes. A high-precision calibration gas mixture was used to evaluate sensor output and calculated carbon dioxide concentration. We assessed the impact of a corrected CO 2 signal on MBW outcomes in a dataset of healthy children and adults and children with lung disease. The EasyOne device uses a respiratory quotient-based adjustment to correct the measured carbon dioxide signal for potential long-term changes in sensor output. In the majority of measurements (89%), this resulted in an overestimation of expired nitrogen concentrations (range -0.7 to 1.7%), and consequently MBW outcomes. Correction of the CO 2 signal reduced the mean (range) cumulative expired volume by 27.1% (−58.1% 1.0%), functional residual capacity by 11.1% (−21.6% 1.2%), and lung clearance index by 18.3% (−44.0% -0.3%). Additionally, within-visit variability was substantially reduced with the corrected signals. Inadequate signal-correction of the measured CO 2 concentration in the EasyOne Pro LAB device leads to a non-systematic error in expired nitrogen concentrations and overestimation of test outcomes. Two-point calibration of the CO 2 sensor may maintain accurate measurement of gas concentrations and overcome this error.
Publisher: Public Library of Science (PLoS)
Date: 14-10-2022
DOI: 10.1371/JOURNAL.PONE.0275866
Abstract: Accurate breath detection is essential for the computation of outcomes in the multiple-breath washout (MBW) technique. This is particularly important in young children, where irregular breathing is common, and the designation of inspirations and expirations can be challenging. To investigate differences between a commercial and a novel breath-detection algorithm and to characterize effects on MBW outcomes in children. We replicated the signal processing and algorithms used in Spiroware software (v3.3.1, Eco Medics AG). We developed a novel breath detection algorithm (custom) and compared it to Spiroware using 2,455 nitrogen (N 2 ) and 325 sulfur hexafluoride (SF 6 ) trials collected in infants, children, and adolescents. In 83% of N 2 and 32% of SF 6 trials, the Spiroware breath detection algorithm rejected breaths and did not use them for the calculation of MBW outcomes. Our custom breath detection algorithm determines inspirations and expirations based on flow reversal and corresponding CO 2 elevations, and uses all breaths for data analysis. In trials with regular tidal breathing, there were no differences in outcomes between algorithms. However, in 10% of pre-school children tests the number of breaths detected differed by more than 10% and the commercial algorithm underestimated the lung clearance index by up to 21%. Accurate breath detection is challenging in young children. As the MBW technique relies on the cumulative analysis of all washout breaths, the rejection of breaths should be limited. We provide an improved algorithm that accurately detects breaths based on both flow reversal and CO 2 concentration.
Publisher: Wiley
Date: 25-05-2021
DOI: 10.1002/PPUL.25464
Abstract: Multiple‐breath inert gas washout (MBW) is a sensitive technique to assess lung volumes and ventilation inhomogeneity in infancy. Poor agreement amongst commercially available setups and a lack of transparency in the underlying algorithms for the computation of infant MBW outcomes currently limit the widespread application of MBW as a surveillance tool in early lung disease. We determined all computational steps in signal processing and the calculation of MBW outcomes in the current infant WBreath/Exhalyzer D setup (Exhalyzer D device, Eco Medics AG WBreath software version 3.28.0, ndd Medizintechnik AG Switzerland). We developed a revised WBreath version based on current consensus guidelines and compared outcomes between the current (3.28.0) and revised (3.52.3) WBreath version. We analyzed 60 visits from 40 infants with cystic fibrosis (CF) and 20 healthy controls at 6 weeks and 1 year of age. Investigation into the algorithms in WBreath 3.28.0 revealed discrepancies from current consensus guidelines, which resulted in a potential overestimation of functional residual capacity (FRC) and underestimation of lung clearance index (LCI). We developed a revised WBreath version (3.52.3), which overall resulted in 6.7% lower FRC (mean (SD) −1.78 (0.99) mL/kg) and 14.1% higher LCI (1.11 (0.57) TO) than WBreath version 3.28.0. Comprehensive investigation into the signal processing and algorithms used for analysis of MBW measurements improves the transparency and robustness of infant MBW data. The revised software version calculates outcomes according to consensus guidelines. Future work is needed to validate and compare outcomes between infant MBW setups.
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.JCF.2021.04.006
Abstract: Lung disease can develop within the first year of life in infants with cystic fibrosis (CF). However, the frequency and severity of respiratory symptoms in infancy are not known. We assessed respiratory symptoms in 50 infants with CF and 50 healthy matched controls from two prospective birth cohort studies. Respiratory symptoms and respiratory rate were documented by standardized weekly interviews throughout the first year. Infants performed multiple breath washout in the first weeks of life. We analyzed 4552 data points (2217 in CF). Respiratory symptoms (either mild or severe) were not more frequent in infants with CF (OR:1.1 % CI:[0.76, 1.59] p=0.6). Higher lung clearance index and higher respiratory rate in infants with CF were not associated with respiratory symptoms. We found no difference in respiratory symptoms between healthy and CF infants. These data indicate that early CF lung disease may not be captured by clinical presentation alone.
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.AJOG.2021.07.027
Abstract: Globally, the number of children born by cesarean delivery is constantly increasing. However, hormonal and physiological changes associated with labor and vaginal delivery are considered necessary for lung maturation. We aimed to assess whether the mode of delivery is associated with changes in respiratory and atopic outcomes during infancy and at school age. We included 578 children, born at ≥37 weeks of gestation, from a prospective birth cohort study. We compared weekly respiratory symptoms throughout the first year of life and infant lung function (tidal breathing and multiple-breath washout) at 5 weeks of age between children born by cesarean delivery (N=114) and those born by vaginal delivery (N=464) after term pregnancy in healthy women. At a follow-up visit conducted at 6 years of age (N=371, of which 65 were delivered by cesarean delivery), we assessed respiratory, atopic, and lung function outcomes (spirometry, body plethysmography, and multiple-breath washout). We performed adjusted regression analyses to examine the association between cesarean delivery and respiratory and atopic outcomes. To account for multiple testing, we used the Bonferroni correction, which led to an adapted significance level of P<.002. During infancy, children born by cesarean delivery did not have more respiratory symptoms than those born by vaginal delivery (median, 4 weeks interquartile range, 7 weeks vs median, 5 weeks interquartile range, 7 weeks adjusted incidence rate ratio, 0.8 95% confidence interval, 0.6-1.0 P=.02). Infant lung function was similar between the groups. Children born by cesarean delivery did not have a higher incidence of "ever wheezing" (adjusted odds ratio, 0.9 95% confidence interval, 0.5-1.8 P=.78) or current asthma (adjusted odds ratio, 0.4 95% confidence interval, 0.0-3.5 P=.42) at school age than those born by vaginal delivery. There was no difference in the lung function parameters between the groups. Cesarean delivery was not associated with respiratory symptoms in the first year of life, nor with different respiratory or atopic outcomes at school age, when compared with vaginal delivery. Our results indicate that there are no long-term consequences on the respiratory health of the child associated with cesarean delivery.
Publisher: American Physiological Society
Date: 09-2021
DOI: 10.1152/JAPPLPHYSIOL.00338.2021
Abstract: We investigated the sensor accuracy of a prominent nitrogen multiple-breath washout (N 2 MBW) device (Eco Medics AG, Duernten, Switzerland) as a possible cause of lack of comparability between outcomes of different MBW devices and methods. We identified an error in the nitrogen concentration calculation of this device, which results in a 10%–15% overestimation of primary outcomes, functional residual capacity, and lung clearance index. It also leads to a significant overestimation of nitrogen back-diffusion into the lungs.
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 08-2021
No related grants have been discovered for Marc-Alexander Oestreich.