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.

Maximum expiratory flow and transpulmonary pressure in the hamster

1978 ◽  
Vol 45 (6) ◽  
pp. 840-845 ◽  
Author(s):  
E. C. Lucey ◽  
B. R. Celli ◽  
G. L. Snider
Keyword(s):  
Vital Capacity ◽  
Simple Technique ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Flow Limitation ◽  
Flow Volume ◽  
System Pressure ◽  
Pleural Surface ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow

Maximum expiratory flow was measured in 19 normal, anesthetized, tracheostomized, supine hamsters from records of forced deflation produced by the application of varying degrees of negative pressure to the tracheostomies of animals whose lungs had been previously inflated to a transpulmonary pressure (PL) of 25 cmH2O. Flow was measured with a pneumotachograph, volume with a constant-volume pressure plethysmograph and pleural surface pressure (Ppl) with a water-filled esophageal catheter. The esophageal pressure measurement overestimated Ppl and a simple technique was based on an estimate of the resting volume of the chest wall. This volume, at which the Ppl is zero, was calculated for anesthetized supine hamsters from the measurement of respiratory-system pressure and PL made independently of esophageal pressure and was found to be about 30% of vital capacity (VC). Flow limitation was present below 70% of VC with a tracheal deflation pressure of -30cmH2O. Negative effort dependence of flow was seen in small segments of the flow-volume curves. Mean +/- SD maximum expiratory flow at 50% VC was 52 +/- 9.5 ml/s or 9.1 VC/s. Upstream resistance was 0.09 +/- 0.03 cmH2O/ml per s.

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.

Pulmonary mechanics during exercise in subjects with chronic airflow obstruction

1980 ◽  
Vol 49 (3) ◽  
pp. 511-515 ◽  
Author(s):  
D. G. Stubbing ◽  
L. D. Pengelly ◽  
J. L. Morse ◽  
N. L. Jones
Keyword(s):  
Tidal Flow ◽  
Airflow Obstruction ◽  
Maximum Flow ◽  
Transpulmonary Pressure ◽  
Pulmonary Mechanics ◽  
Flow Volume ◽  
Tidal Breathing ◽  
Flow Rates ◽  
Control Value ◽  
Expiratory Flow

A body plethysmograph was used to measure pulmonary mechanics in six subjects with chronic airflow obstruction during steady states at rest and during exercise at 200 and 400 kpm . min-1. The mean forced expired volume in 1 s was 1.32 liters (39.2% predicted). The flow rates during tidal breathing reached the maximum expiratory flow-volume (MEFV) curve in all but one subject, and on exercise they all reached the MEFV curve. Total lung capacity did not change significantly, but functional residual capacity increased to 104% of the control value (P less than 0.05) and residual volume increased to 113.3% of the control value (P less than 0.02). The MEFV curves did not change and tidal flow rates in excess of th MEFV curve were not seen. Dynamic compliance fell with increasing exercise to 52.8% (P less than 0.01) and static expiratory pulmonary compliance to 90.2% of the control value. Transpulmonary pressures during tidal breathing when expiratory flow reached the MEFV curve increased to progressively higher values as the work load increased. At low work loads there were several subjects with negative transpulmonary pressure when maximum flow rates were present. In patients with chronic airflow obstruction, little change occurs during exercise in pulmonary mechanics; the tidal flow patterns are dominated by the expired flow-volume curve, which is not changed by exercise; maximum flow occurs in some patients when transpulmonary pressure is still negative.

Analysis of Maximum Expiratory Flow Volume Curves Using Canonical Correlation Analysis

1985 ◽  
Vol 24 (02) ◽  
pp. 91-100 ◽  
Author(s):  
W. van Pelt ◽  
Ph. H. Quanjer ◽  
M. E. Wise ◽  
E. van der Burg ◽  
R. van der Lende
Keyword(s):  
Correlation Analysis ◽  
Canonical Correlation Analysis ◽  
Canonical Correlation ◽  
Flow Volume ◽  
Non Linear ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Relationship Of ◽  
The Relationship ◽  
Age And Sex

SummaryAs part of a population study on chronic lung disease in the Netherlands, an investigation is made of the relationship of both age and sex with indices describing the maximum expiratory flow-volume (MEFV) curve. To determine the relationship, non-linear canonical correlation was used as realized in the computer program CANALS, a combination of ordinary canonical correlation analysis (CCA) and non-linear transformations of the variables. This method enhances the generality of the relationship to be found and has the advantage of showing the relative importance of categories or ranges within a variable with respect to that relationship. The above is exemplified by describing the relationship of age and sex with variables concerning respiratory symptoms and smoking habits. The analysis of age and sex with MEFV curve indices shows that non-linear canonical correlation analysis is an efficient tool in analysing size and shape of the MEFV curve and can be used to derive parameters concerning the whole curve.

Simulation of the effects of mechanical nonhomogeneities on expiratory flow from human lungs

1990 ◽  
Vol 68 (6) ◽  
pp. 2550-2563 ◽  
Author(s):  
R. K. Lambert
Keyword(s):  
Fluid Mechanics ◽  
Left Lung ◽  
Flow Volume ◽  
Alveolar Pressure ◽  
Peripheral Airways ◽  
Volume Curve ◽  
Human Lungs ◽  
Flow Volume Curve ◽  
Expired Gas ◽  
Expiratory Flow

A computational model for expiration from lungs with mechanical nonhomogeneities was used to investigate the effect of such nonhomogeneities on the distribution of expiratory flow and the development of alveolar pressure differences between regions. The nonhomogeneities used were a modest constriction of the peripheral airways and a 50% difference in compliance between regions. The model contains only two mechanically different regions but allows these to be as grossly distributed as left lung-right lung or to be distributed as a set of identical pairs of parallel nonhomogeneous regions with flows from each merging in a specified bronchial generation. The site of flow merging had no effect on the flow-volume curve but had a significant effect on the development of alveolar pressure differences (delta PA). With the peripheral constriction, greater values of delta PA developed when flows were merged peripherally rather than centrally. The opposite was true in the case of a compliance nonhomogeneity. The delta PA values were smaller at submaximal flows. Plots of delta PA vs. lung volume were similar to those obtained experimentally. These results were interpreted in terms of the expression used for the fluid mechanics of the merging flows. delta PA was greater when the viscosity of the expired gas was increased or when its density was reduced. Partial forced expirations were shown to indicate the presence of mechanical nonhomogeneity.

scholarly journals Longitudinal Examination of the Shape of the Maximum Expiratory Flow‐Volume Curve in Young Adults Following SARS‐CoV‐2 Infection

2021 ◽  
Vol 35 (S1) ◽  
Author(s):  
Jonathon Stickford ◽  
Marc Augenreich ◽  
Valesha Province ◽  
Nina Stute ◽  
Abigail Stickford ◽  
...  
Keyword(s):  
Young Adults ◽  
Flow Volume ◽  
Volume Curve ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve ◽  
Expiratory Flow ◽  
Longitudinal Examination
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