Forced expirations and maximum expiratory flow-volume curves during sustained microgravity on SLS-1

1996 ◽  
Vol 81 (1) ◽  
pp. 33-43 ◽  
Author(s):  
A. R. Elliott ◽  
G. K. Prisk ◽  
H. J. Guy ◽  
J. M. Kosonen ◽  
J. B. West
Keyword(s):  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Forced Expiratory Volume ◽  
Slight Reduction ◽  
Flow Volume ◽  
Lung Volumes ◽  
Volume Curve ◽  
Supine Posture ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow

Gravity is known to influence the mechanical behavior of the lung and chest wall. However, the effect of sustained microgravity (microG) on forced expirations has not previously been reported. Tests were carried out by four subjects in both the standing and supine postures during each of seven preflight and four postflight data-collection sessions and four times during the 9 days of microG exposure on Spacelab Life Sciences-1. Compared with preflight standing values, peak expiratory flow rate (PEFR) was significantly reduced by 12.5% on flight day 2 (FD2), 11.6% on FD4, and 5.0% on FD5 but returned to standing values by FD9. The supine posture caused a 9% reduction in PEFR. Forced vital capacity and forced expired volume in 1 s were slightly reduced (approximately 3-4%) on FD2 but returned to preflight standing values on FD4 and FD5, and by FD9 both values were slightly but significantly greater than standing values. Forced vital capacity and forced expiratory volume in 1 s were both reduced in the supine posture (approximately 8-10%). Forced expiratory flows at 50% and between 25 and 75% of vital capacity did not change during microG but were reduced in the supine posture. Analysis of the maximum expiratory flow-volume curve showed that microG caused no consistent change in the curve configuration when individual in-flight days were compared with preflight standing curves, although two subjects did show a slight reduction in flows at low lung volumes from FD2 to FD9. The interpretation of the lack of change in curve configuration must be made cautiously because the lung volumes varied from day to day in flight. Therefore, the flows at absolute lung volumes in microG and preflight standing are not being compared. The supine curves showed a subtle but consistent reduction in flows at low lung volumes. The mechanism responsible for the reduction in PEFR is not clear. It could be due to a lack of physical stabilization when performing the maneuver in the absence of gravity or a transient reduction in respiratory muscle strength.

Changes in flow-volume curve configuration with bronchoconstriction and bronchodilation

1986 ◽  
Vol 61 (6) ◽  
pp. 2243-2251 ◽  
Author(s):  
C. R. O'Donnell ◽  
R. G. Castile ◽  
J. Mead
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Flow Volume ◽  
Slope Ratio ◽  
Lung Volumes ◽  
Volume Curve ◽  
Before And After ◽  
Lower Lung ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve

Changes in the configuration of maximum expiratory flow-volume (MEFV) curves following mild degrees of bronchodilation or bronchoconstriction were studied in five normal and five asthmatic subjects. In a volume-displacement plethysmograph, MEFV curves were performed before and after inhalation of aerosolized isoproterenol (I) or histamine (H). Five filtered MEFV curves were averaged, and slope ratio vs. volume (SR-V) plots were obtained from averaged curves. Following I, maximal flows at 75% of the vital capacity (VC) were decreased in asthmatics but not in normal subjects. Flows at 50 and 25% of the VC increased in normal subjects and asthmatics, whereas VC′s were unchanged. In asthmatics, sudden large decreases in flow (bumps) occurred at lower lung volumes following I. H reduced flows over the entire VC, with greater reductions occurring in asthmatics than in normals, particularly at low lung volumes. In asthmatics, VC was slightly reduced, and bumps in MEFV curve configuration occurred at higher lung volumes or were abolished entirely following H. A reduction in the amount of configurational detail appreciable in MEFV curves following histamine in asthmatics was best seen in SR-V plots. Following H, SR′s decreased regularly with decreasing lung volume in all the asthmatics but in none of the normals. This was the single most striking finding of this study. Mild I- and H-induced perturbations of airway bronchomotor tone produced small but consistent changes in MEFV curve configuration.(ABSTRACT TRUNCATED AT 250 WORDS)

Area under the expiratory flow–volume curve (AEX): actual versus approximated values

2019 ◽  
Vol 68 (2) ◽  
pp. 403-411 ◽  
Author(s):  
Octavian C Ioachimescu ◽  
James K Stoller
Keyword(s):  
Diagnostic Performance ◽  
Vital Capacity ◽  
Flow Volume ◽  
Prior Work ◽  
Strong Correlations ◽  
Functional Impairments ◽  
Lung Volumes ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Expiratory Flow

Previous work has shown that area under the expiratory flow–volume curve (AEX) performs well in diagnosing and stratifying respiratory physiologic impairment, thereby lessening the need to measure lung volumes. Extending this prior work, the current study assesses the accuracy and utility of several geometric approximations of AEX based on standard instantaneous flows. These approximations can be used in spirometry interpretation when actual AEX measurements are not available. We analysed 15 308 spirometry tests performed on subjects who underwent same-day lung volume assessments in the Pulmonary Function Laboratory. Diagnostic performance of four AEX approximations (AEX1–4) was compared with that of actual AEX. All four computations included forced vital capacity (FVC) and various instantaneous flows: AEX1 was derived from peak expiratoryflow (PEF); AEX2 from PEF and forced expiratoryflow at 50% FVC (FEF50); AEX3 from FVC, PEF, FEF at 25% FVC (FEF25) and at 75% FVC (FEF75), while AEX4 was computed from all four flows, PEF, FEF25, FEF50 and FEF75. Mean AEX, AEX1, AEX2, AEX3 and AEX4 were 6.6, 8.3, 6.7, 6.3 and 6.1 L2/s, respectively. All four approximations had strong correlations with AEX, that is, 0.95–0.99. Differences were the smallest for AEX–AEX4, with a mean of 0.52 (95% CI 0.51 to 0.54) and a SD of 0.75 (95% CI 0.74 to 0.76) L2/s. In the absence of AEX and in addition to the usual spirometric variables used for assessing functional impairments, parameters such as AEX4 can provide reasonable approximations of AEX and become useful new tools in future interpretative strategies.

EVALUATION OF MIST TENT THERAPY IN CYSTIC FIBROSIS USING MAXIMUM EXPIRATORY FLOW VOLUME CURVE

PEDIATRICS ◽  
1972 ◽  
Vol 50 (2) ◽  
pp. 299-306
Author(s):  
E. K. Motoyama ◽  
L. E. Gibson ◽  
C. J. Zigas
Keyword(s):  
Cystic Fibrosis ◽  
Initial Period ◽  
Forced Expiratory Volume ◽  
Lower Airway ◽  
Flow Volume ◽  
Ventilatory Function ◽  
Volume Curve ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Lower Airway Obstruction

The effect of home mist tent therapy in cystic fibrosis was reexamined using the measurement of maximum expiratory flow volume (MEFV) curves, forced expiratory volume (FEV1), and vital capacity (VC) in 16 patients every 2 weeks during a period of 4 to 5 months. In half of the patients the studies were made during an initial period of 8 to 12 weeks off and then a similar period on nocturnal mist tent therapy; in the other half the test conditions were reversed. No evidence of improvement in ventilatory function was found in these patients during the use of a mist tent; instead there was a small but significant decline in their ventilatory function. Home visits were made and bacterial contamination of mist tent equipment was noted in more than two-thirds of the tents in spite of careful cleaning instructions to the parents. The MEFV curve was found to be a simple yet sensitive test of evaluating lower airway obstruction in cystic fibrosis.

Dependence of maximal flow-volume curves on time course of preceding inspiration

1993 ◽  
Vol 75 (3) ◽  
pp. 1155-1159 ◽  
Author(s):  
E. D'Angelo ◽  
E. Prandi ◽  
J. Milic-Emili
Keyword(s):  
Time Course ◽  
Vital Capacity ◽  
Normal Subjects ◽  
Forced Expiratory Volume ◽  
Flow Volume ◽  
Maximal Flow ◽  
Lung Volumes ◽  
Residual Capacity ◽  
Expiratory Flow ◽  
Volume Range

Thirteen normal subjects, sitting in a body plethysmograph and breathing through a pneumotachograph, performed forced vital capacity maneuvers after a rapid inspiration without or with an end-inspiratory pause (maneuvers 1 and 2) and after a slow inspiration without or with an end-inspiratory pause (maneuvers 3 and 4), the pause lasting 4–6 s. Inspirations were initiated close to functional residual capacity. At all lung volumes, expiratory flow was larger with maneuver 1 than with any other maneuver and, over the upper volume range, larger with maneuver 3 than with maneuver 4, whereas it was similar for maneuvers 2 and 4. Relative to corresponding values with maneuver 4, peak expiratory flow was approximately 16 and approximately 4% larger with maneuvers 1 and 3, respectively, whereas forced expiratory volume in 1 s increased by approximately 5% only with maneuver 1. The time dependence of maximal flow-volume curves is consistent with the presence of viscoelastic elements within the respiratory system (D'Angelo et al. J. Appl. Physiol. 70: 2602–2610, 1991).

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.

Pulmonary function in men after oxygen breathing at 3.0 ATA for 3.5 h

1991 ◽  
Vol 71 (3) ◽  
pp. 878-885 ◽  
Author(s):  
J. M. Clark ◽  
R. M. Jackson ◽  
C. J. Lambertsen ◽  
R. Gelfand ◽  
W. D. Hiller ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Large Change ◽  
Forced Expiratory Volume ◽  
Diffusing Capacity ◽  
Mild Degree ◽  
Oxygen Breathing ◽  
Multiple Organs ◽  
Expiratory Flow

As a pulmonary component of Predictive Studies V, designed to determine O2 tolerance of multiple organs and systems in humans at 3.0–1.5 ATA, pulmonary function was evaluated at 1.0 ATA in 13 healthy men before and after O2 exposure at 3.0 ATA for 3.5 h. Measurements included flow-volume loops, spirometry, and airway resistance (Raw) (n = 12); CO diffusing capacity (n = 11); closing volumes (n = 6); and air vs. HeO2 forced vital capacity maneuvers (n = 5). Chest discomfort, cough, and dyspnea were experienced during exposure in mild degree by most subjects. Mean forced expiratory volume in 1 s (FEV1) and forced expiratory flow at 25–75% of vital capacity (FEF25–75) were significantly reduced postexposure by 5.9 and 11.8%, respectively, whereas forced vital capacity was not significantly changed. The average difference in maximum midexpiratory flow rates at 50% vital capacity on air and HeO2 was significantly reduced postexposure by 18%. Raw and CO diffusing capacity were not changed postexposure. The relatively large change in FEF25–75 compared with FEV1, the reduction in density dependence of flow, and the normal Raw postexposure are all consistent with flow limitation in peripheral airways as a major cause of the observed reduction in expiratory flow. Postexposure pulmonary function changes in one subject who convulsed at 3.0 h of exposure are compared with corresponding average changes in 12 subjects who did not convulse.

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

The Shape of the Maximum Expiratory Flow Volume Curve

CHEST Journal ◽  
1988 ◽  
Vol 94 (4) ◽  
pp. 799-806 ◽  
Author(s):  
Mary C. Kapp ◽  
E.Neil Schachter ◽  
Gerald J. Beck ◽  
Lucinda R. Maunder ◽  
Theodore J. Witek
Keyword(s):  
Flow Volume ◽  
Volume Curve ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve ◽  
Expiratory Flow

A comparison of lung volumes between divers and submariners in the Royal Navy

1984 ◽  
Vol 70 (3) ◽  
pp. 143-148
Author(s):  
G. M. Clifford ◽  
D. J. Smith ◽  
Cardine S. M. Searing
Keyword(s):  
Linear Regression ◽  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Forced Expiratory Volume ◽  
Royal Navy ◽  
Predictive Equations ◽  
Lung Volumes ◽  
Job Classification ◽  
Single Breath ◽  
Expected Values

SummaryA comparison of spirometric values in divers and submariners of the Royal Navy and their physical characteristics was undertaken. Four hundred and twenty-two subjects were included in the study, of whom 192 were divers and 230 submariners. Measurements of forced vital capacity (FYC), forced expiratory volume in one second (FEY1) and FEY1/FYC ratio were made using a single breath wedge spirometer (YitalographR). The data was analysed by multiple linear regression and analysis of variance. FYC and FEY1 increased with height and decreased with age though inclusion of a quadratic age term showed that the decline with age did not begin until the mid-thirties, casting doubt on the validity of predictive equations which assume a linear decrease from age 25. The divers had significantly larger lung volumes than the submariners though in the former this did not correlate with either experience or job classification. The FEY1/FYC ratio declined with age in both groups. It was also shown that those individuals with a large FYC tend to have a relatively lower FEY1/FYC ratio than those with small FYCs. Predictive equations for both divers and submariners were calculated which are more appropriate for determining expected values for the two groups than hose currently in use.

Density dependence of maximal flow in dogs with central and peripheral obstruction

1983 ◽  
Vol 55 (3) ◽  
pp. 717-725 ◽  
Author(s):  
R. G. Castile ◽  
O. F. Pedersen ◽  
J. M. Drazen ◽  
R. H. Ingram
Keyword(s):  
Density Dependence ◽  
Vital Capacity ◽  
Forced Expiration ◽  
Flow Volume ◽  
Partial Obstruction ◽  
Volume Curve ◽  
Before And After ◽  
Lower Lung ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve

In 12 anesthetized, tracheotomized, vagotomized, open-chested, mongrel dogs we measured end and side hole airway pressures during forced expiration using a Pitot static probe. Volume was obtained as the integral of flow from a dog plethysmograph with frequency response adequate to 20 Hz. Equal pressure points (EPPs) and choke points (CPs) were located with dogs breathing air or a mixture of 80% helium-20% oxygen (HeO2) before and after partial obstruction of the trachea and intravenous histamine and propranolol. At 50% of vital capacity (VC) the CP was in the trachea in 11 of 12 dogs. Partial obstruction of the trachea decreased flow during the plateau of the maximum expiratory flow-volume curve (MEFVC) with the CP remaining in the trachea. The MEFVC plateau was extended to a lower lung volume. At 50% of VC the EPP moved downstream and density dependence remained high. Histamine and propranolol caused EPPs and CPs to move towards the periphery and density dependence to decrease. The shape of the MEFVC changed as the plateau was shortened and, in some instances, abolished. A plateau on the MEFVC could be regenerated by partial obstruction of the trachea. This was accompanied by return of the CP to the trachea and an increase in density dependence. Changes in density dependence were found to be a result of both the relocation of sites of flow limitation and differences in local CP areas with HeO2 and air.

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