Airway closure and closing volume

1979 ◽  
Vol 46 (1) ◽  
pp. 24-30 ◽  
Author(s):  
L. Forkert ◽  
S. Dhingra ◽  
N. R. Anthonisen
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Regional Perfusion ◽  
Phase Iii ◽  
Breath Hold ◽  
Closing Volume ◽  
Residual Volume ◽  
Airway Closure ◽  
Lung Volumes ◽  
Phase Iv

Using boluses of radioactive Xe we compared regional N2O uptake with regional perfusion distribution during open glottis breath hold in five seated men. Measurements were made near residual volume, at closing volume (CV), above CV and when possible, between CV and residual volume (RV). At low lung volumes basal N2O uptake was small whereas basal blood flow was not. This discrepancy was interpreted as evidence of airway closure and was quantitated. All subjects showed extensive basal closure near RV. At closing volume four of five subjects demonstrated closure and some closure was evident in these subjects at volumes in excess of CV. The increase in airway closure with decreasing lung volume was much greater below CV than above it. Conventional CV tracings were obtained using helium boluses; the height of phase IV was positively correlated with the change in airway closure between CV and RV as assessed by the N2O technique. The slope of phase III did not correlate with the amount of airway closure measured at CV. We concluded that the conventionally measured CV is not the volume at which airway closure begins but that the onset of phase IV reflects an increase in basal airway closure and the height of phase IV reflects the amount of basal closure between CV and RV.

Effect of previous volume history on airway closure

1983 ◽  
Vol 55 (2) ◽  
pp. 294-299
Author(s):  
H. W. Greville ◽  
L. J. Slykerman ◽  
P. A. Easton ◽  
N. R. Anthonisen
Keyword(s):  
Regional Distribution ◽  
Lung Parenchyma ◽  
Breath Hold ◽  
Closing Volume ◽  
Airway Closure ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Normal Humans ◽  
Volume History ◽  
Previous Volume

We studied the effect of volume history on airway closure in six healthy males ranging from 32 to 67 yr of age. The method used was to compare the regional distribution of 133Xe boluses distributed according to N2O uptake during open-glottis breath-hold maneuvers with the regional distribution of boluses of intravenously injected 133Xe. Measurements were made at two lung volumes, one close to residual volume (RV) and the other just below closing volume. The required volume was reached either by expiring from total lung capacity or by inspiring from RV. Although there was considerable airway closure in the basal regions of the lungs at both lung volumes studied, the degree of airway closure was not dependent on the previous volume history. We conclude that the airways concerned with closure have a volume-pressure hysteresis similar to that of the lung parenchyma. Furthermore in normal humans the volume-pressure hysteresis of the lung is not secondary to airway closure.

Regional distribution of ventilation at residual volume in induced bronchospasm

1982 ◽  
Vol 53 (2) ◽  
pp. 361-366
Author(s):  
L. Delaunois ◽  
R. Boileau ◽  
J. Diodatti ◽  
J. Gauthier ◽  
R. R. Martin
Keyword(s):  
Lung Volume ◽  
Regional Distribution ◽  
Phase Iii ◽  
Residual Volume ◽  
Single Breath ◽  
Airway Opening ◽  
Collateral Pathways ◽  
Total Lung Resistance ◽  
Downward Slope ◽  
Phase Iv

The regional distribution of a bolus of gas inhaled at residual volume (RV) is attributed to regional airway closure and is responsible for the phase IV of the single-breath washout during the following deflation. As bronchospasm increases the range of airway opening pressures through the lung, the regional distribution of the bolus could change with effects on the shape of the single-breath washout. We investigated the regional distribution of boluses inhaled at RV and their single-breath washouts during methacholine-induced bronchospasm in prone dogs. With increasing total lung resistance (RL) we first observed in five out of eight animals a preferential “redistribution” of the bolus to the upper caudal regions of the lung, which could be partially attributed to the increased lung volume at RV. When maximal RL was attained, the bolus was evenly distributed through all regions of the lung in these animals with disappearance of phase IV and increased slope of phase III, and a final decrease of tracer concentration at low lung volumes was observed. We conclude from these data that increased bronchomotor tone in dogs results in a less homogeneous intraregional distribution of the bolus with increased slope of phase III and in a more even interregional distribution leading to disappearance of phase IV. In severe bronchospasm the downward slope at low lung volume suggests intraregional closed lung units emptying through collateral pathways into still open neighboring units.

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.

Respiratory system reactance is an independent determinant of asthma control

2013 ◽  
Vol 115 (9) ◽  
pp. 1360-1369 ◽  
Author(s):  
Vanessa J. Kelly ◽  
Scott A. Sands ◽  
R. Scott Harris ◽  
Jose G. Venegas ◽  
Nathan J. Brown ◽  
...  
Keyword(s):  
Asthma Control ◽  
Respiratory System ◽  
Lung Volume ◽  
Strong Predictor ◽  
Closing Volume ◽  
Forced Oscillation Technique ◽  
Airway Closure ◽  
Lung Volumes ◽  
Ventilation Heterogeneity ◽  
Peripheral Airway

The mechanisms underlying not well-controlled (NWC) asthma remain poorly understood, but accumulating evidence points to peripheral airway dysfunction as a key contributor. The present study tests whether our recently described respiratory system reactance (Xrs) assessment of peripheral airway dysfunction reveals insight into poor asthma control. The aim of this study was to investigate the contribution of Xrs to asthma control. In 22 subjects with asthma, we measured Xrs (forced oscillation technique), spirometry, lung volumes, and ventilation heterogeneity (inert-gas washout), before and after bronchodilator administration. The relationship between Xrs and lung volume during a deflation maneuver yielded two parameters: the volume at which Xrs abruptly decreased (closing volume) and Xrs at this volume (Xrscrit). Lowered (more negative) Xrscrit reflects reduced apparent lung compliance at high lung volumes due, for example, to heterogeneous airway narrowing and unresolved airway closure or near closure above the critical lung volume. Asthma control was assessed via the 6-point Asthma Control Questionnaire (ACQ6). NWC asthma was defined as ACQ6 > 1.0. In 10 NWC and 12 well-controlled subjects, ACQ6 was strongly associated with postbronchodilator (post-BD) Xrscrit ( R2 = 0.43, P < 0.001), independent of all measured variables, and was a strong predictor of NWC asthma (receiver operator characteristic area = 0.94, P < 0.001). By contrast, Xrs measures at lower lung volumes were not associated with ACQ6. Xrscrit itself was significantly associated with measures of gas trapping and ventilation heterogeneity, thus confirming the link between Xrs and airway closure and heterogeneity. Residual airway dysfunction at high lung volumes assessed via Xrscrit is an independent contributor to asthma control.

Influence of expiratory flow on closing capacity at low expiratory flow rates

1975 ◽  
Vol 39 (1) ◽  
pp. 60-65 ◽  
Author(s):  
J. R. Rodarte ◽  
R. E. Hyatt ◽  
D. A. Cortese
Keyword(s):  
Lung Volume ◽  
Normal Subjects ◽  
Closing Volume ◽  
Residual Volume ◽  
Dependent Lung ◽  
Flow Rates ◽  
Single Breath ◽  
Expiratory Flow ◽  
Expiratory Flow Rates ◽  
Phase Iv

Single-breath oxygen (SBO2) tests at expiratory flow rates of 0.2, 0.5, and 1.01/s were performed by 10 normal subjects in a body plethysmograph. Closing capacity (CC)--the absolute lung volume at which phase IV began--increased significantly with increases in flow. Five subjects were restudied with a 200-ml bolus of 100% N2 inspired from residual volume after N2 washout by breathing 100% O2 and similar results were obtained. An additional five subjects performed SBO2 tests in the standing, supine, and prone positions; closing volume (CV)--the lung volume above residual volume at which phase IV began--also increased with increases of expiratory flow. The observed increase in CC with increasing flow did not appear to result from dependent lung regions reaching some critical “closing volume” at a higher overall lung volume. In normal subjects, the phase IV increase in NI concentration may be caused by the asynchronous onset of flow limitation occurring initially in dependent regions.

Postinspiratory mixing in the lung and cardiogenic oscillations

1981 ◽  
Vol 51 (4) ◽  
pp. 922-928 ◽  
Author(s):  
R. Arieli ◽  
A. J. Olszowka ◽  
H. D. Van Liew
Keyword(s):  
Mechanical Properties ◽  
Functional Residual Capacity ◽  
Pressure Wave ◽  
Phase Iii ◽  
Breath Hold ◽  
Residual Volume ◽  
Residual Capacity ◽  
Expired Gas ◽  
Cardiogenic Oscillations ◽  
Phase Iv

Subjects inspired a 300-ml bolus of indicator gas cocktail (5% each of SF6, Ar, Ne, and He) form residual volume (RV), then inspired air to functional residual capacity (FRC). There was no evidence that a 10-s breath hold changed the relative concentrations or amounts of indicator gases in phases III and IV of expiration or allowed additional gas to mix into the RV, but the breath hold caused cardiogenic oscillations (CO) in expired gas to decrease in height. The units responsible for cardiogenic troughs and peaks are different from the units responsible for phases III and IV, respectively, in that the oscillation troughs had a lower He/SF6 ratio than the peaks whereas phase III had a higher He/SF6 than phase IV. We explain the CO as due to variation in mechanical properties, leading to variation in response to the pressure wave caused by the heart, in units that are relatively near to each other. We conclude that there is little or no postinspiratory mixing between distant lung units, but the dampening of CO suggests that units that are close to each other can mix if time is allowed.

Airway closure and reopening assessed by the alveolar capsule oscillation technique

1996 ◽  
Vol 80 (6) ◽  
pp. 2077-2084 ◽  
Author(s):  
D. R. Otis ◽  
F. Petak ◽  
Z. Hantos ◽  
J. J. Fredberg ◽  
R. D. Kamm
Keyword(s):  
Lung Volume ◽  
Input Impedance ◽  
Transpulmonary Pressure ◽  
Closing Volume ◽  
Airway Closure ◽  
Breathing Cycle ◽  
Abrupt Increase ◽  
Consistent Effect ◽  
Peripheral Airways

An alveolar capsule oscillation technique was used to determine 1) the lobe pressure and volume at which airways close and reopen, 2) the effect of expiration rate on closing volume and pressure, 3) the phase in the breathing cycle at which airway closure occurs, and 4) the site of airway closure. Experiments were conducted in excised dog lobes; closure was detected by an abrupt increase in the input impedance of surfacemounted alveolar capsules. Mean transpulmonary pressure (Ptp) at closure was slightly less than zero (Ptp = -2.3 cmH2O); the corresponding mean reopening pressure was Ptp = 14 cmH2O. The expiration rate varied between 1 and 20% of total lobe capacity per second and had no consistent effect on the closing volume and pressure. When lung volume was cycled up to frequencies of 0.2 Hz, closure generally occurred on expiration rather than inspiration. These observations support the conclusion that mechanical collapse, rather than meniscus formation, is the most likely mechanism producing airway closure in normal excised dog lungs. Analysis of measured acoustic impedances and reopening pressures suggests that closure occurs in the most peripheral airways. Reopening during inspiration was often observed to consist of a series of stepwise decreases in capsule impedance, indicating a sequence of opening events.

Lung volume specificity of inspiratory muscle training

1994 ◽  
Vol 77 (2) ◽  
pp. 789-794 ◽  
Author(s):  
G. E. Tzelepis ◽  
D. L. Vega ◽  
M. E. Cohen ◽  
F. D. McCool
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Inspiratory Muscle ◽  
Control Group ◽  
Residual Volume ◽  
Maximal Inspiratory Pressure ◽  
Muscle Training ◽  
Inspiratory Capacity ◽  
Lung Volumes ◽  
Before And After

We examined the extent to which training-related increases of inspiratory muscle (IM) strength are limited to the lung volume (VL) at which the training occurs. IM strength training consisted of performing repeated static maximum inspiratory maneuvers. Three groups of normal volunteers performed these maneuvers at one of three lung volumes: residual volume (RV), relaxation volume (Vrel), or Vrel plus one-half of inspiratory capacity (Vrel + 1/2IC). A control group did not train. We constructed maximal inspiratory pressure-VL curves before and after a 6-wk training period. For each group, we found that the greatest improvements in strength occurred at the volume at which the subjects trained and were significantly greater for those who trained at low (36% for RV and 26% for Vrel) than at high volumes (13% for Vrel + 1/2IC). Smaller increments in strength were noted at volumes adjacent to the training volume. The range of vital capacity (VC) over which strength was increased was greater for those who trained at low (70% of VC) than at high VL (20% of VC). We conclude that the greatest improvements in IM strength are specific to the VL at which training occurs. However, the increase in strength, as well as the range of volume over which strength is increased, is greater for those who trained at the lower VL.

Regional intrapulmonary gas distribution in awake and anesthetized-paralyzed prone man

1978 ◽  
Vol 45 (4) ◽  
pp. 528-535 ◽  
Author(s):  
K. Rehder ◽  
T. J. Knopp ◽  
A. D. Sessler
Keyword(s):  
Mechanical Ventilation ◽  
Vertical Distribution ◽  
Vertical Gradient ◽  
Phase Iii ◽  
Residual Volume ◽  
Gas Distribution ◽  
Lung Volumes ◽  
Regional Lung ◽  
Residual Capacity ◽  
The Vertical Distribution

The intrapulmonary distribution of inspired gas (ventilation/unit lung volume, VI), functional residual capacity (FRC), closing capacity (CC), and the slope of phase III were determined in five awake and five anesthetized-paralyzed volunteers who were in the prone position with the abdomen unsupported. After induction of anesthesia-paralysis, FRC was less in four of five subjects and CC was consistently less. At FRC there was no difference in the vertical gradient of regional lung volumes between the awake and anesthetized-paralyzed prone subjects. Also, there was no difference in VI between the two states. The normalized slope of phase III decreased consistently with induction of anesthesia-paralysis, but the vertical distribution of a 133Xe bolus inhaled from residual volume was not different between the two states. The data of the study are compatible with 1) a pattern of expansion of the respiratory system during anesthesia-paralysis and mechanical ventilation different than that during spontaneous breathing and 2) a more uniform intraregional distribution of inspired gas and/or a different sequence of emptying during anesthesia-paralysis.

Demonstration of airway closure in man

1975 ◽  
Vol 38 (6) ◽  
pp. 1117-1125 ◽  
Author(s):  
L. A. Engel ◽  
A. Grassino ◽  
N. R. Anthonisen
Keyword(s):  
Chest Wall ◽  
Pulmonary Circulation ◽  
Gas Flow ◽  
Regional Perfusion ◽  
Breath Holding ◽  
Breath Hold ◽  
Gas Mixture ◽  
Airway Closure ◽  
Dependent Lung ◽  
Compton Scatter

After partial equilibration of the lung with a N2O gas mixture absorption of N2O by the pulmonary circulation results in a flow of gas into the lungs during breath holding. A bolus of 133Xe introduced at the mouth at the beginning of the breath hold is carried in by the gas flow and distributed according to regional perfusion. In three subjects, breath holding at FRC, apex-to-base distribution of a 133Xe bolud delivered by N2O absorption (Xecar) was similar to that of a bolus injected intravenously (Xeiv). Near RV however, much less of Xecar penetrated into dependent zones than expected from the distribution of Xeiv. In fact, distribution of Xecar did not differ from that of a slowly inhaled bolus. Correction for Compton scatter in the chest wall, measured in one subject, accounted only in part for the radioactivity recorded over dependent lung regions. The findings indicate that near RV some but not all of the dependent airways must be closed. Furthermore, the distribution of airway closure completely accounts for the distribution of a bolus inhaled from RV.

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