Increased gravitational stress does not alter maximum expiratory flow

1985 ◽  
Vol 59 (1) ◽  
pp. 28-33 ◽  
Author(s):  
D. Pyszczynski ◽  
S. N. Mink ◽  
N. R. Anthonisen
Keyword(s):  
Vital Capacity ◽  
Total Lung Capacity ◽  
Maximum Flow ◽  
Flow Volume ◽  
Lung Capacity ◽  
Gravitational Stress ◽  
Regional Lung ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Capacity Data

We measured maximum expiratory flow-volume (MEFV) curves in six seated subjects during normal (+1 Gz) and increased (+2 and +3 Gz) gravitational stress. Full MEFV curves, initiated at total lung capacity, were recorded, as were partial MEFV curves, initiated at approximately 60% of the vital capacity. Data were acquired in all subjects breathing air at +1 and +2 Gz; results were available for three subjects breathing 80% He-20% O2 at +1 and +2 Gz, and in two subjects, results were obtained at +3 Gz. Changes in gravitational stress were not associated with changes of either full or partial MEFV curves. The known increase in differences of regional lung volume and recoil caused by increased gravitational stress did not influence maximum expiratory flow. Though increased gravitational stress probably changed regional emptying sequences little during full MEFV maneuvers, substantial changes of emptying sequence were expected during partial maneuvers. It is possible that such changes in emptying sequence occurred but were not associated with changes in maximum flow because the latter was determined by choking in central airways common to all regions.

Changes in regional emptying sequence need not change maximum expiratory flow

1986 ◽  
Vol 60 (6) ◽  
pp. 1834-1838 ◽  
Author(s):  
R. B. Filuk ◽  
N. R. Anthonisen
Keyword(s):  
Vital Capacity ◽  
Total Lung Capacity ◽  
Young Men ◽  
Forced Expiration ◽  
Flow Volume ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow

Nine normal young men inhaled boluses of He at the onset of slow vital capacity (VC) inspirations. During the subsequent VC expirations, we measured expired flow, volume, and He concentrations. Expirations consisted of full or partial maximum expiratory flow-volume (MEFV) maneuvers. Full maneuvers were forced expirations from total lung capacity (TLC). Partial maneuvers were accomplished by expiring slowly from TLC to 70, 60, 50, and 40% VC and then initiating forced expiration. Expired He concentrations from full and partial maneuvers were compared with each other and with those resulting from slow expirations. At comparable volumes less than 50% VC, flow during partial and full MEFV maneuvers did not differ. Expired He concentrations were higher during partial maneuvers than during full ones; at the onset of partial maneuvers upper zone emptying predominated, whereas this was not the case at the same lung volumes during maneuvers initiated at TLC. We observed substantial differences in regional emptying sequence that did not influence maximum expiratory flow.

Heterogeneous airway tone in asthmatic subjects

1992 ◽  
Vol 73 (6) ◽  
pp. 2328-2332 ◽  
Author(s):  
G. Julia-Serda ◽  
N. A. Molfino ◽  
K. R. Chapman ◽  
P. A. McClean ◽  
N. Zamel ◽  
...  
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Lung Parenchyma ◽  
Flow Volume ◽  
Lung Capacity ◽  
Group I ◽  
Expiratory Flow ◽  
Airway Tone ◽  
Volume History

We examined the effect of volume history on the dynamic relationship between airways and lung parenchyma (relative hysteresis) in 20 asthmatic subjects. The acoustic reflection technique was employed to evaluate changes in airway cross-sectional areas during a slow continuous expiration from total lung capacity to residual volume and inspiration back to total lung capacity. Lung volume was measured continuously during this quasi-static maneuver. We studied three anatomic airway segments: extra- and intrathoracic tracheal and main bronchial segments. Plots of airway area vs. lung volume were obtained for each segment to assess the relative magnitude and direction of the airway and parenchymal hysteresis. We also performed maximal expiratory flow-volume and partial expiratory flow-volume curves and calculated the ratio of maximal to partial flow rates (M/P) at 30% of the vital capacity. We found that 10 subjects (group I) showed a significant predominance of airway over parenchymal hysteresis (P < 0.005) at the extra- and intrathoracic tracheal and main bronchial segments; these subjects had high M/P ratios [1.53 +/- 0.27 (SD)]. The other 10 subjects (group II) showed similar airway and parenchymal hysteresis for all three segments and significantly lower M/P ratios (1.16 +/- 0.20, P < 0.01). We conclude that the effect of volume history on the relative hysteresis of airway and lung parenchyma and M/P ratio at 30% of vital capacity in nonprovoked asthmatic subjects is variable. We suggest that our findings may result from heterogeneous airway tone in asthmatic subjects.

Influence of Breath Holding at Total Lung Capacity on Maximal Expiratory Flow Measurements

1981 ◽  
Vol 60 (1) ◽  
pp. 11-15 ◽  
Author(s):  
T. Higenbottam ◽  
T. J. H. Clark
Keyword(s):  
Vital Capacity ◽  
Total Lung Capacity ◽  
Breath Hold ◽  
Flow Volume ◽  
Flow Measurements ◽  
Lung Capacity ◽  
Maximal Expiratory Flow ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Expiratory Flow

1. Forced exhalations performed from volumes below total lung capacity, so-called partial expiratory flow-volume curves, are suggested to be more sensitive in detecting airways bronchoconstriction than maximal expiratory flow-volume curves begun at total lung capacity. 2. In eight healthy men both maximal and partial expiratory flow-volume curves were measured where breath was held at total lung capacity or 70% of vital capacity respectively, for either 0 or 15 s before performing the forced exhalation. An histamine aerosol was used to provoke bronchoconstriction. 3. The results showed that the 15 s breath hold caused greater reduction in expiratory flow rates after histamine for both maximal and partial expiratory flow-volume curves than either manoeuvres performed with no breath hold. 4. A breath hold of 15 s at total lung capacity appeared to make the maximal expiratory flow-volume curve as sensitive as a partial expiratory flow-volume curve in detecting the response to histamine as well as providing measurements of forced expiratory volume in 1 s and vital capacity. Forced spirometry after a 15 s breath hold at total lung capacity therefore provides an easy and sensitive technique for detecting bronchoconstriction.

An isovolume method for analysis of density dependence of maximal expiratory flows

1987 ◽  
Vol 62 (5) ◽  
pp. 2115-2120 ◽  
Author(s):  
I. Rubinstein ◽  
A. W. Vanek ◽  
P. A. McClean ◽  
R. Boucher ◽  
N. Zamel ◽  
...  
Keyword(s):  
Density Dependence ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Residual Volume ◽  
Flow Volume ◽  
Large Variability ◽  
Lung Capacity ◽  
Coefficients Of Variation ◽  
Maximum Expiratory Flow ◽  
The Mean

The usual method of measuring density dependence of maximum expiratory flows is superimposition at total lung capacity or residual volume of maximum expiratory flow volume (MEFV) curves obtained breathing air and a mixture of 80% He plus 20% O2 (HeO2). A major problem with this technique is the large variability in results, which has been thought to be due to errors in matching lung volumes on both gases. Accordingly, we obtained MEFV curves breathing air and HeO2 using a bag-in-the-box system so that the curves breathing the two gas mixtures could be directly superimposed without removing the mouthpiece (isovolume). Ten healthy, nonsmoking subjects performed MEFV curves on each gas mixture for six consecutive experiments. We compared the increase in flow at 50% of vital capacity (delta Vmax50) and volume of isoflow (Viso) by superimposing and matching the MEFV curves at total lung capacity, at residual volume, and using the isovolume method. The variability of each method was assessed by the mean intersubject and intrasubject coefficients of variation. In all subjects, the mean delta Vmax50 and Viso as well as their corresponding coefficients of variation were not significantly different among the three methods. We conclude that, in healthy nonsmoking young adults, the method chosen for superimposing and matching MEFV curves has no effect on the variability of delta Vmax50 and Viso.

Pattern and mechanism of airway response to hypocapnia in normal subjects

1979 ◽  
Vol 47 (1) ◽  
pp. 8-12 ◽  
Author(s):  
C. F. O'Cain ◽  
M. J. Hensley ◽  
E. R. McFadden ◽  
R. H. Ingram
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Oxygen Mixture ◽  
Flow Volume ◽  
Mixture Density ◽  
Lung Capacity ◽  
Airway Constriction ◽  
Maximal Expiratory Flow ◽  
Airway Response ◽  
Expiratory Flow

We examined the bronchoconstriction produced by airway hypocapnia in normal subjects. Maximal expiratory flow at 25% vital capacity on partial expiratory flow-volume (PEFV) curves fell during hypocapnia both on air and on an 80% helium- 20% oxygen mixture. Density dependence also fell, suggesting predominantly small airway constriction. The changes seen on PEFV curves were not found on maximal expiratory flow-volume curves, indicating the inhalation to total lung capacity substantially reversed the constriction. Pretreatment with a beta-sympathomimetic agent blocked the response, whereas atropine pretreatment did not, suggesting that hypocapnia affects airway smooth muscle directly, not via cholinergic efferents.

Airway responses to inhaled histamine in asymptomatic smokers and nonsmokers

1977 ◽  
Vol 42 (4) ◽  
pp. 508-513 ◽  
Author(s):  
N. E. Brown ◽  
E. R. McFadden ◽  
R. H. Ingram
Keyword(s):  
Vital Capacity ◽  
Total Lung Capacity ◽  
Aerosol Deposition ◽  
Flow Volume ◽  
Maximal Flow ◽  
Airway Reactivity ◽  
Lung Capacity ◽  
Large Airway ◽  
Airway Response ◽  
Airway Responses

Bronchia reactivity to inhaled histamine was assessed in asymptomatic cigarette smokers and in nonsmoking atopic and nonatopic subjects. The only prechallenge between-group difference was the ratio of maximal flow on 80% helium-20% oxygen (Vmax HeO2) to maximal flow on air (Vmax air) from partial expiratory flow volume curves at 25% vital capacity (25% VC PEFV): Mean +/- SEM for smokers 1.18 /+- 0.06, atopics 1.45 +/- 0.08, nonatopics 1.51 +/- 0.03. This suggests that prior to inhalation to total lung capacity, the predominant site of resistance at flow limitation was in smaller airways of the smokers and in larger airways of both groups of nonsmokers. Following inhalation of histamine, smokers and nonatopics had similar changes in lung volumes and Vmax air which were less than in atopics. The Vmax HeO2/Vmax air ratios at 25% VC PEFV increased in smokers and decreased in nonsmokers: smokers 1.48 +/- 0.08, atopics 1.22 +/- 0.10, nontopics 1.16 +/- 0.06. This suggests a predominant large airway response in smokers and a prominent small airway response in nonsmokers. These responses may reflect differences in the predominant site of aerosol deposition rather than in airway reactivity.

Correlations of maximum expiratory flow with small airway dimensions and pathology

1982 ◽  
Vol 52 (2) ◽  
pp. 346-351 ◽  
Author(s):  
N. Berend ◽  
W. M. Thurlbeck
Keyword(s):  
Maximum Flow ◽  
Transpulmonary Pressure ◽  
Small Airway ◽  
Flow Volume ◽  
Human Lungs ◽  
Muscle Hyperplasia ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Inflammation Score ◽  
Airway Dimensions

Pressure-volume and maximum expiratory flow-volume curves with air and a He-O2 mixture were performed in 25 excised human lungs. Small airway dimensions were measured, and the degree of various small airway lesions and emphysema was graded. Correlations were then made between the maximum flow (Vmax) at a transpulmonary pressure (PL) of 5 cmH2O and these measurements and scores. Small airway dimensions correlated poorly with Vmax. However, significant correlations were obtained between Vmax and the inflammation score (P less than 0.05), fibrosis score (P less than 0.05), and emphysema grade (P less than 0.01) but not smooth muscle hyperplasia or pigmentation. Neither the increase in flow with He-O2 nor the volume of flow correlated significantly with any small airway measurement or score.

OBSTRUCTIVE DISEASE OF THE AIRWAYS IN CYSTIC FIBROSIS

PEDIATRICS ◽  
1968 ◽  
Vol 41 (3) ◽  
pp. 560-573
Author(s):  
Robert B. Mellins ◽  
O. Robert Levine ◽  
Roland H. Ingram ◽  
Alfred P. Fishman
Keyword(s):  
Cystic Fibrosis ◽  
Vital Capacity ◽  
Maximum Flow ◽  
Transpulmonary Pressure ◽  
Forced Expiration ◽  
Lung Volumes ◽  
Flow Rates ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

A study of the interrelationships of instantaneous air flow, lung volume, and transpulmonary pressure over the range of the vital capacity has demonstrated striking differences in the determinants of maximum expiratory flow in cystic fibrosis and asthma. At high lung volumes, maximum expiratory flow rates in asthma are limited by the mechanical characteristics of the lungs and airways, whereas in cystic fibrosis and in the normal they are dependent on effort. At lower lung volumes, maximum expiratory flow rates are relatively more reduced in cystic fibrosis than in asthma and pressures in excess of those required to produce maximum flow actually depress flow. Also, forced expiration is associated with a transient reversal in the slope of the single breath nitrogen curve in cystic fibrosis and not in asthma. From these studies it is concluded that: (1) airway obstruction is less uniform and involves larger airways in cystic fibrosis than in asthma, and (2) increased expiratory pressure is associated with collapse of some of the larger airways over most of the range of the vital capacity in cystic fibrosis. A major clinical implication of these studies is that the effectiveness of cough is impaired by large airway collapse in cystic fibrosis.

Interdependence of regional expiratory flows limits alveolar pressure differences

1990 ◽  
Vol 69 (4) ◽  
pp. 1413-1418 ◽  
Author(s):  
G. P. Topulos ◽  
G. J. Nielan ◽  
G. M. Glass ◽  
J. J. Fredberg
Keyword(s):  
Strong Evidence ◽  
Transpulmonary Pressure ◽  
Flow Volume ◽  
Alveolar Pressure ◽  
Volume Curve ◽  
Regional Lung ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve ◽  
Expiratory Flow ◽  
Degree Of Heterogeneity

Wilson et al. (J. Appl. Physiol. 59:1924-28, 1985) have asserted that interdependence of regional expiratory flows could cause differences of interregional alveolar pressures to relax to time-independent limits during forced deflation. To test the hypothesis that such limiting differences do arise, we examined regional alveolar pressures during complete and partial maximally forced deflations of six excised canine lungs. Alveolar pressures were monitored using alveolar capsules on each of six lobes during forced deflations initiated at transpulmonary pressures of 30, 20, 15, and 10 cmH2O. In all lungs and in all maneuvers, interregional heterogeneity of alveolar pressure increased rapidly early in the deflation but much less so or not at all later in the deflation. When we compared complete with partial forced deflations, 16 of 24 maneuvers in six lungs showed clear evidence that as deflation progressed the degree of heterogeneity at isovolumic points became independent of the transpulmonary pressure from which the deflation was initiated. That is, alveolar pressures relaxed to limiting interregional differences that did not depend on time elapsed from the onset of the deflation. These data offer strong evidence of the existence of limiting differences. Such behavior implies that the sequence of regional emptying is controlled by a competition of opposing influences: nonuniformities of airway and parenchymal properties promoting nonuniformity of emptying vs. interdependence of regional expiratory flows promoting uniformity. As nonuniformity of regional pressures grows so do those factors that oppose that nonuniformity. These data underscore the insensitivity of maximum expiratory flow-volume curve configuration to the underlying inhomogeneous pattern of regional lung emptying.

PULMONARY MECHANICS IN ASTHMA AND CYSTIC FIBROSIS

PEDIATRICS ◽  
1971 ◽  
Vol 48 (1) ◽  
pp. 64-72
Author(s):  
Alois Zapletal ◽  
Etsuro K. Motoyama ◽  
Lewis E. Gibson ◽  
Arend Bouhuys
Keyword(s):  
Cystic Fibrosis ◽  
Maximum Flow ◽  
Pulmonary Mechanics ◽  
Flow Volume ◽  
Flow Rates ◽  
Normal Limits ◽  
Children With Asthma ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

Maximum expiratory flow rates on flow-volume curves are often decreased below normal limits in children with asthma or cystic fibrosis who are clinically well and whose standard spirometric tests are within normal limits. In particular, maximum flow rates at small lung volumes (25% of vital capacity) are decreased. Maximum expiratory flow-volume (MEFV) curves provide a sensitive and quantitative assessment of small airway obstruction in these and other obstructive lung conditions.

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