Estimation of lung functional residual capacity by the multiple-breath washout test versus bodyplethysmography in healthy subjects

2020 ◽  
Author(s):  
Galina Nekludova ◽  
Alexander Cherniak
Keyword(s):  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Multiple Breath Washout ◽  
Residual Capacity

Crural diaphragm activation during dynamic contractions at various inspiratory flow rates

1998 ◽  
Vol 85 (2) ◽  
pp. 451-458 ◽  
Author(s):  
Jennifer Beck ◽  
Christer Sinderby ◽  
Lars Lindström ◽  
Alex Grassino
Keyword(s):  
Chest Wall ◽  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Total Lung Capacity ◽  
Inspiratory Flow ◽  
Transdiaphragmatic Pressure ◽  
Flow Rates ◽  
Lung Capacity ◽  
Dynamic Contractions ◽  
Residual Capacity

The purpose of this study was to evaluate the influence of velocity of shortening on the relationship between diaphragm activation and pressure generation in humans. This was achieved by relating the root mean square (RMS) of the diaphragm electromyogram to the transdiaphragmatic pressure (Pdi) generated during dynamic contractions at different inspiratory flow rates. Five healthy subjects inspired from functional residual capacity to total lung capacity at different flow rates while reproducing identical Pdi and chest wall configuration profiles. To change the inspiratory flow rate, subjects performed the inspirations while breathing across two different inspiratory resistances (10 and 100 cmH2O ⋅ l−1 ⋅ s), at mouth pressure targets of −10, −20, −40, and −60 cmH2O. The diaphragm electromyogram was recorded and analyzed with control of signal contamination and electrode positioning. RMS values obtained for inspirations with identical Pdi and chest wall configuration profiles were compared at the same percentage of inspiratory duration. At inspiratory flows ranging between 0.1 and 1.4 l/s, there was no difference in the RMS for the inspirations from functional residual capacity to total lung capacity when Pdi and chest wall configuration profiles were reproduced ( n = 4). At higher inspiratory flow rates, subjects were not able to reproduce their chest wall displacements and adopted different recruitment patterns. In conclusion, there was no evidence for increased demand of diaphragm activation when healthy subjects breathe with similar chest wall configuration and Pdi profiles, at increasing flow rates up to 1.4 l/s.

Correction of sensor crosstalk error in Exhalyzer D multiple-breath washout device significantly impacts outcomes in children with cystic fibrosis

2021 ◽  
Author(s):  
Florian Wyler ◽  
Marc-Alexander H. Oestreich ◽  
Bettina Sarah Frauchiger ◽  
Kathryn A. Ramsey ◽  
Philipp T. Latzin
Keyword(s):  
Carbon Dioxide ◽  
Cystic Fibrosis ◽  
Functional Residual Capacity ◽  
Nitrogen Concentration ◽  
Lung Clearance ◽  
Cross Sensitivity ◽  
Carbon Dioxide Gas ◽  
Lung Clearance Index ◽  
Multiple Breath Washout ◽  
Residual Capacity

Rationale: Nitrogen multiple-breath washout is an established technique to assess functional residual capacity and ventilation inhomogeneity in the lung. Accurate measurement of gas concentrations is essential for the appropriate calculation of clinical outcomes. Objectives: We investigated the accuracy of oxygen and carbon dioxide gas sensor measurements used for the indirect calculation of nitrogen concentration in a commercial multiple-breath washout device (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and its impact on functional residual capacity and lung clearance index. Methods: High precision calibration gas mixtures and mass spectrometry were used to evaluate sensor output. We assessed the impact of corrected signal processing on multiple-breath washout outcomes in a dataset of healthy children and children with cystic fibrosis using custom analysis software. Results: 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 multiple-breath washout outcomes. Breath-by-breath correction of this error reduced the mean (SD) cumulative expired volume by 19.6 (5.0)%, functional residual capacity by 8.9 (2.2)%, and lung clearance index by 11.9 (4.0)%. It also substantially reduced the level of the tissue nitrogen signal at the end of measurements. Conclusions: Inadequate correction for cross sensitivity in the oxygen and carbon dioxide gas sensors of the Exhalyzer D device leads to an overestimation of functional residual capacity and lung clearance index. Correction of this error is possible and could be applied by re-analyzing the measurements in an updated software version.

Airway closure during anesthesia: a comparison between resident-gas and argon-bolus techniques

1979 ◽  
Vol 47 (4) ◽  
pp. 874-881 ◽  
Author(s):  
G. Hedenstierna ◽  
J. Santesson
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Healthy Subjects ◽  
Abrupt Onset ◽  
Closing Volume ◽  
Residual Volume ◽  
Airway Closure ◽  
Venous Admixture ◽  
Residual Capacity ◽  
Nitrogen Concentrations

Airway closure was measured in awake and then anesthetized supine healthy subjects with the argon-bolus and the resident-gas (nitrogen) techniques simultaneously. The preinspiratory lung volume for the closing volume maneuver was varied from residual volume to closing capacity (CC). Comparative measurements were also performed in the upright and supine positions in awake subjects. Closing volume (CV) was consistently larger with the bolus technique in supine subjects both when awake and when anesthetized (difference between methods 0.1--0.2 l, P less than 0.01), whereas no difference between the methods was noted in upright subjects. The lower “nitrogen CV” in supine subjects may be due to a shorter vertical lung height with a smaller range of nitrogen concentrations, resulting in a less abrupt onset of phase IV (taken to indicate CV). CV was not significantly affected by the preinspiratory lung volume with either technique, and CC was unchanged when anesthesia was instituted. Functional residual capacity (FRC) was reduced with anesthesia (mean reduction: 0.6 l, P less than 0.01) and FRC-CC became negative in all subjects with either technique. This implies intermittent or continuous airway closure during anesthesia and the possibility of increased venous admixture.

scholarly journals Ventilation heterogeneity measured by multiple breath inert gas testing is not affected by inspired oxygen concentration in healthy humans

2017 ◽  
Vol 122 (6) ◽  
pp. 1379-1387 ◽  
Author(s):  
Susan R. Hopkins ◽  
Ann R. Elliott ◽  
G. Kim Prisk ◽  
Chantal Darquenne
Keyword(s):  
Oxygen Concentration ◽  
Healthy Subjects ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Healthy Humans ◽  
Ventilation Heterogeneity ◽  
Multiple Breath Washout ◽  
Residual Capacity ◽  
Gaussian Fit ◽  
Inspired Oxygen

Multiple breath washout (MBW) and oxygen-enhanced MRI techniques use acute exposure to 100% oxygen to measure ventilation heterogeneity. Implicit is the assumption that breathing 100% oxygen does not induce changes in ventilation heterogeneity; however, this is untested. We hypothesized that ventilation heterogeneity decreases with increasing inspired oxygen concentration in healthy subjects. We performed MBW in 8 healthy subjects (4 women, 4 men; age = 43 ± 15 yr) with normal pulmonary function (FEV1 = 98 ± 6% predicted) using 10% argon as a tracer gas and oxygen concentrations of 12.5%, 21%, or 90%. MBW was performed in accordance with ERS-ATS guidelines. Subjects initially inspired air followed by a wash-in of test gas. Tests were performed in balanced order in triplicate. Gas concentrations were measured at the mouth, and argon signals rescaled to mimic a N2 washout, and analyzed to determine the distribution of specific ventilation (SV). Heterogeneity was characterized by the width of a log-Gaussian fit of the SV distribution and from Sacin and Scond indexes derived from the phase III slope. There were no significant differences in the ventilation heterogeneity due to altered inspired oxygen: histogram width (hypoxia 0.57 ± 0.11, normoxia 0.60 ± 0.08, hyperoxia 0.59 ± 0.09, P = 0.51), Scond (hypoxia 0.014 ± 0.011, normoxia 0.012 ± 0.015, hyperoxia 0.010 ± 0.011, P = 0.34), or Sacin (hypoxia 0.11 ± 0.04, normoxia 0.10 ± 0.03, hyperoxia 0.12 ± 0.03, P = 0.23). Functional residual capacity was increased in hypoxia ( P = 0.04) and dead space increased in hyperoxia ( P = 0.0001) compared with the other conditions. The acute use of 100% oxygen in MBW or MRI is unlikely to affect ventilation heterogeneity. NEW & NOTEWORTHY Hyperoxia is used to measure the distribution of ventilation in imaging and MBW but may alter the underlying ventilation distribution. We used MBW to evaluate the effect of inspired oxygen concentration on the ventilation distribution using 10% argon as a tracer. Short-duration exposure to hypoxia (12.5% oxygen) and hyperoxia (90% oxygen) during MBW had no significant effect on ventilation heterogeneity, suggesting that hyperoxia can be used to assess the ventilation distribution.

Assessment of maximal expiratory pressure in healthy adults

1988 ◽  
Vol 64 (5) ◽  
pp. 2215-2219 ◽  
Author(s):  
I. Rubinstein ◽  
A. S. Slutsky ◽  
A. S. Rebuck ◽  
P. A. McClean ◽  
R. Boucher ◽  
...  
Keyword(s):  
Functional Residual Capacity ◽  
Muscle Function ◽  
Healthy Subjects ◽  
Normal Values ◽  
Scuba Diving ◽  
The Other ◽  
Expiratory Muscle ◽  
Hands On ◽  
Wide Variability ◽  
Residual Capacity

Maximal static expiratory pressure developed at the mouth (PEmax) provides a useful clinical index of expiratory muscle function; however, the range of normal values among laboratories shows considerable variation. We examined the hypothesis that the wide variability could be attributable to the differences in technique among laboratories. We measured PEmax at functional residual capacity (PEmax FRC) in 28 healthy subjects using the following five techniques: 1) using a scuba-type mouthpiece with the cheeks supported by the hands ("hands on"), 2) without supporting the cheeks ("no hands"), 3) using a rigid, circular mouthpiece (2.8 cm ID, "tube"), 4) using the scuba-type mouthpiece but with the cheeks supported by an observer ("other hands"), and 5) using a large-bore circular mouthpiece (4.1 cm ID, "new tube"). Mean PEmax FRC obtained with hands on was significantly higher than no-hands and tube methods. PEmax FRC values obtained by the other-hands and new-tube maneuvers were similar to the hands-on maneuver. We conclude that the technique used to measure PEmax FRC can significantly affect the results and suggest that it should be measured using a large-bore circular mouthpiece or a scuba-diving mouthpiece with the cheeks supported.

scholarly journals Leaks during multiple-breath washout: characterisation and influence on outcomes

2018 ◽  
Vol 4 (1) ◽  
pp. 00012-2017 ◽  
Author(s):  
Nina Lenherr ◽  
Kathryn A. Ramsey ◽  
Kerstin Jost ◽  
Linn Hornwall ◽  
Florian Singer ◽  
...  
Keyword(s):  
Functional Residual Capacity ◽  
Cycle Duration ◽  
European Respiratory Society ◽  
Physiological Noise ◽  
Lung Clearance ◽  
Air Leaks ◽  
Heterogeneous Effects ◽  
Lung Clearance Index ◽  
Multiple Breath Washout ◽  
Residual Capacity

Nitrogen multiple-breath washout (N2MBW) is increasingly used in patients with cystic fibrosis. The current European Respiratory Society/American Thoracic Society consensus statement for MBW recommends the rejection of measurements with leaks. However, it is unclear whether this is necessary for all types of leaks. Here, our aim was to 1) model and 2) apply air leaks, and 3) to assess their influence on the primary MBW outcomes of lung clearance index and functional residual capacity.We investigated the influence of air leaks at various locations (pre-, intra- and post-capillary), sizes, durations and stages of the washout. Modelled leaks were applied to existing N2MBW data from 10 children by modifying breath tables. In addition, leaks were applied to the equipment during N2MBW measurements performed by one healthy adolescent.All modelled and applied leaks resulted in statistically significant but heterogeneous effects on lung clearance index and functional residual capacity. In all types of continuous inspiratory leaks exceeding a certain size, the end of the washout was not reached. For practical application, we illustrated six different “red flags”, i.e. signs that enable easy identification of leaks during measurements.Air leaks during measurement significantly influence N2MBW outcomes. The influence of leaks on MBW outcomes is dependent on the location, relation to breath cycle, duration, stage of washout and size of the leak. We identified a range of signs to help distinguish leaks from physiological noise.

Dispersion of 0.5- to 2-μm aerosol in μG and hypergravity as a probe of convective inhomogeneity in the lung

1999 ◽  
Vol 86 (4) ◽  
pp. 1402-1409 ◽  
Author(s):  
Chantal Darquenne ◽  
John B. West ◽  
G. Kim Prisk
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Distal Part ◽  
Sedimentation Velocity ◽  
Residual Volume ◽  
Gas Mixing ◽  
Residual Capacity ◽  
Expired Gas

We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (μG) and hypergravity (∼1.6 G). Boluses of 0.5-, 1-, and 2-μm-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-μm-diameter particles for which sedimentation velocity is low, the differences between dispersion in μG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between μG and 1 G.

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