Effect of lung volume on ventilation distribution

Crawford, A. B. H.; Cotton, David; Paiva, Manuel; Engel, L. A.

doi:10.1152/jappl.1989.66.6.2502

Cited by 44 publications

(60 citation statements)

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“…Nevertheless, SIII may be influenced by breathing pattern, and raised volume protocols have arguably been regarded as being more robust [24,32,33]. However, shift in VC due to training effects introduces bias [24].…”

Section: Physiological and Methodological Considerationsmentioning

confidence: 99%

A new double-tracer gas single-breath washout to assess early cystic fibrosis lung disease

et al. 2012

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In cystic fibrosis (CF), tests for ventilation inhomogeneity are sensitive but not established for clinical routine. We assessed feasibility of a new double-tracer gas single-breath washout (SBW) in school-aged children with CF and control subjects, and compared SBW between groups and with multiple-breath nitrogen washout (MBNW).Three SBW and MBNW were performed in 118 children (66 with CF) using a side-stream ultrasonic flowmeter setup. The double-tracer gas containing 5% sulfur hexafluoride and 26.3% helium was applied during one tidal breath. Outcomes were SBW phase III slope (SIIIDTG), MBNWderived lung clearance index (LCI), and indices of acinar (Sacin) and conductive (Scond) ventilation inhomogeneity.SBW took significantly less time to perform than MBNW. SBW and MBNW were feasible in 109 (92.4%) and 98 (83.0%) children, respectively. SIIIDTG differed between children with CF and controls, mean¡SD was -456.7¡492.8 and -88.4¡129.1 mg?mol?L -1 , respectively. Abnormal SIIIDTG was present in 36 (59%) children with CF. SIIIDTG was associated with LCI (r5 -0.58) and Sacin (r5 -0.58), but not with Scond.In CF, steeply sloping SIIIDTG potentially reflects ventilation inhomogeneity near the acinus entrance. This tidal SBW is a promising test to assess ventilation inhomogeneity in an easy and fast way.

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Section: Physiological and Methodological Considerationsmentioning

confidence: 99%

A new double-tracer gas single-breath washout to assess early cystic fibrosis lung disease

et al. 2012

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“…The large baseline variability of these indices increases the threshold for determining significant BDR and reduces their capacity to discriminate between health and disease in terms of bronchial responsiveness. A number of physiological factors, such as lung volume, inhomogeneous airway closure and changing tidal volume, affect ventilation distribution, particularly those indices derived from phase III slope analysis [13][14][15]. Moreover, in obstructive airways disease, the relationship between airways obstruction and ventilation inhomogeneity is heterogeneous, thus varying from one subject to another [16].…”

Section: Repeatabilitymentioning

confidence: 99%

Repeatability and bronchodilator reversibility of lung function in young children

et al. 2012

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Knowledge of short-and longer-term repeatability of lung function in health and disease is essential to determine bronchodilator reversibility thresholds and to recognise if changes in lung function represent disease progression, therapeutic intervention or normal variability.Multiple-breath washout indices (lung clearance index, conductive ventilation inhomogeneity (Scond)) and specific airway resistance (sRaw) were measured in healthy children and stable wheezers. Measurements were performed at baseline and after 20 min without intervention to assess repeatability and determine bronchodilator reversibility thresholds. Bronchodilator reversibility was assessed by repeating baseline measurements 20 min after inhaled salbutamol. 28 healthy controls, mean¡SD age 6.1¡0.7 years and 62 wheezers 5.4¡0.6 years were tested. Baseline variability in multiple-breath washout indices and sRaw was not significantly different between wheezers and healthy controls. Significant bronchodilator reversibility was only observed in wheezers for Scond (16%), but in both wheezers (37%) and healthy controls (20%) for sRaw. Some wheezers and healthy controls demonstrated increases in multiple-breath washout indices post-bronchodilator.Lung clearance index and sRaw demonstrate low baseline variability in healthy and diseased subjects. Neither multiple-breath washout indices nor sRaw are ideal for assessing bronchodilator reversibility in young children with stable wheeze. These findings will help to interpret the effect of therapeutic interventions in children with respiratory diseases. @ERSpublications Multiple-breath washout indices and sRaw do not reflect bronchodilator reversibility in young children with stable wheeze

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“…1, inset) and thus results in a positive value for the SF 6 -He phase III slope difference (15). The absence of gravity was expected to result in an equal reduction in the phase III slopes of SF 6 and He (due to the common loss of the gravitational CDI component on both gases), and thus no change in SF 6 -He slope difference was expected. However, studies performed during spaceflight (i.e., sustained G) not only found that significant inhomogeneity in pulmonary ventilation persisted in G but surprisingly that the SF 6 -He slope difference was abolished, which was due to a greater fall in the phase III slope of SF 6 than He (39).…”

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confidence: 99%

“…The inclusion of two poorly soluble inert gases, e.g., sulfur hexafluoride (SF 6 ) and helium (He), with widely differing diffusivities (diffusion for He being 6 times greater than that of SF 6 ) results in differential mixing of these gases and provides a sensitive index of peripheral gas mixing (16). In healthy humans, the ventilatory inhomogeneity at the acinar level (DCDI) is responsible for the steeper phase III slope for SF 6 than He (Fig. 1, inset) and thus results in a positive value for the SF 6 -He phase III slope difference (15).…”

mentioning

confidence: 99%

“…The absence of gravity was expected to result in an equal reduction in the phase III slopes of SF 6 and He (due to the common loss of the gravitational CDI component on both gases), and thus no change in SF 6 -He slope difference was expected. However, studies performed during spaceflight (i.e., sustained G) not only found that significant inhomogeneity in pulmonary ventilation persisted in G but surprisingly that the SF 6 -He slope difference was abolished, which was due to a greater fall in the phase III slope of SF 6 than He (39). In an attempt to elucidate the mechanism(s) responsible for the unexpected behavior in the SF 6 -He slope difference observed in space (i.e., sustained G), SBW tests have been performed during transient G on board a National Aeronautics and Space Administration KC-135 G research aircraft (12,26).…”

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confidence: 99%

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Effect of 60° head-down tilt on peripheral gas mixing in the human lung

Olfert

Prisk

2004

Journal of Applied Physiology

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Olfert, I. Mark, and G. Kim Prisk. Effect of 60°head-down tilt on peripheral gas mixing in the human lung. J Appl Physiol 97: 827-834, 2004. First published April 16, 2004 10.1152/ japplphysiol.01379.2003The phase III slope of sulfur hexafluoride (SF 6) in a single-breath washout (SBW) is greater than that of helium (He) under normal gravity (i.e., 1G), thus resulting in a positive SF 6-He slope difference. In microgravity (G), SF6-He slope difference is smaller because of a greater fall in the phase III slope of SF 6 than He. We sought to determine whether increasing thoracic fluid volume using 60°head-down tilt (HDT) in 1G would produce a similar effect to G on phase III slopes of SF 6 and He. Single-breath vital capacity (SBW) and multiple-breath washout (MBW) tests were performed before, during, and 60 min after 1 h of HDT. Compared with baseline (SF 6 1.050 Ϯ 0.182%/l, He 0.670 Ϯ 0.172%/l), the SBW phase III slopes for both SF 6 and He tended to decrease during HDT, reaching nadir at 30 min (SF 6 0.609 Ϯ 0.211%/l, He 0.248 Ϯ 0.138%/l; P ϭ 0.08 and P ϭ 0.06, respectively). In contrast to G, the magnitude of the phase III slope decrease was similar for both SF 6 and He; therefore, no change in SF 6-He slope difference was observed. MBW analysis revealed a decrease in normalized phase III slopes at all time points during HDT, for both SF 6 (P Ͻ 0.01) and He (P Ͻ 0.01). This decrease was due to changes in the acinar, and not the conductive, component of the normalized phase III slope. These findings support the notion that changes in thoracic fluid volume alter ventilation distribution in the lung periphery but also demonstrate that the effect during HDT does not wholly mimic that observed in G.phase III slope; single-breath washout; multiple-breath washout; helium; sulfur hexafluoride NONUNIFORMITY OF PULMONARY ventilation results from inhomogeneities in both convective and diffusive gas transport, sometimes referred to as convective-dependent inhomogeneity (CDI) and diffusion-convection-dependent inhomogeneity (DCDI) (7). CDI effects may be induced by either gravitational mechanisms, such as topographic differences in pulmonary ventilation resulting from regional differences in pleural pressure (2, 27), or nongravitational mechanisms, such as differing mechanical properties (e.g., lung compliance) among regional lung units (7,37). DCDI effects involve a complex interaction between both convection and diffusion and are believed to occur in the branching structure of the lung when convective and diffusive transport mechanisms are similar in magnitude, which in humans is reported to be at or near the level of the entrance of the acinus (32). The effects of DCDI can be thought of as occurring on a small scale, i.e., intraregional, whereas CDI principally occurs between regions of the lung, i.e., interregional. Studies performed in microgravity (G) have shown that a substantial portion (ϳ75%) of ventilatory inhomogeneity (as evidenced by the phase III slope) is due to DCDI effects (20, 38 -40). However, there is...

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Effect of lung volume on ventilation distribution

Cited by 44 publications

References 0 publications

A new double-tracer gas single-breath washout to assess early cystic fibrosis lung disease

A new double-tracer gas single-breath washout to assess early cystic fibrosis lung disease

Repeatability and bronchodilator reversibility of lung function in young children

Effect of 60° head-down tilt on peripheral gas mixing in the human lung

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