Early Detection of Obstructive Lung Disease by Analysis of Maximal Expiratory Flow-Volume Curves

The ratios of the instantaneous tangent slopes to corresponding chord slopes are sensitive to curvatures of flow-volume curves; and these dimensionless slope ratios, SR, plotted against fractional volumes remaining to be expired, VCf, are sensitive to the shape of flow-volume curves but insenitive to flow or volume magnitudes. SR-VCf curves predicted for lungs which empty homogeneously differ substantially from those predicted for lungs which empty nonhomogeneously, the latter showing systematic increases in SR with VCf which may extend beyond the homogeneous range. SR-VCf curves for some 80 healthy subjects show systematic changes with age (range 6–64 yr), but all are consistent with advanced obstructive lung disease (chronic bronchitis, emphysema, asthma) are consistent with nonhomogeneous emptying, but it does not seem likely that SR-VCf curves will prove useful for detecting early stages of disease.

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IMPACT OF AWARENESS CAMPAIGNS FOR EARLY DETECTION OF OBSTRUCTIVE LUNG DISEASE

CHEST Journal ◽

10.1016/j.chest.2020.05.353 ◽

2020 ◽

Vol 157 (6) ◽

pp. A292

Author(s):

R. Ulmeanu ◽

R. Nedelcu ◽

R. Nemes ◽

F. Mihaltan

Keyword(s):

Early Detection ◽

Lung Disease ◽

Obstructive Lung Disease ◽

Awareness Campaigns

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Pattern and mechanism of airway response to hypocapnia in normal subjects

Journal of Applied Physiology ◽

10.1152/jappl.1979.47.1.8 ◽

1979 ◽

Vol 47 (1) ◽

pp. 8-12 ◽

Cited By ~ 35

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.

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Flow-Volume Curves in Infants with Lung Disease

PEDIATRICS ◽

10.1542/peds.72.4.517 ◽

1983 ◽

Vol 72 (4) ◽

pp. 517-522

Author(s):

S. Godfrey ◽

E. Bar-Yishay ◽

I. Arad ◽

L. I. Landau ◽

L. M. Taussig

Keyword(s):

Lung Disease ◽

Airway Obstruction ◽

Lung Volume ◽

Airway Resistance ◽

Whole Body ◽

Small Airways ◽

Forced Expiration ◽

Flow Volume ◽

Complete Evaluation ◽

Expiratory Flow

Partial expiratory flow-volume maneuvers have been performed on nine occasions on six infants with a variety of pulmonary problems using a new tech nique for thoracic compression. The infants were placed within an inflatable bag that was, itself, within a canvas bag. By sudden controlled inflation of the inner bag at end inspiration, partial expiratory flow-volume curves were generated and recorded by means of a face mask and pneumotachograph. By comparing these flow results with those airway resistance and lung volume measurements obtained from the infants in whole body plethysmography and by noting the effect of inhaling a helium/oxygen gas mixture, it was possible to partition the airway obstruction between large and small airways. The presence of small airway obstruction was noted in the absence of changes in airway resistance or lung volume in several instances. A complete evaluation of airway function should include this test of forced expiration for greater understanding and treatment of lung disease in infancy.

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Shape Analysis of the Maximal Expiratory Flow Volume Curve Among the Patients with Various Kind of Pulmonary Diseases

Tuberculosis and Respiratory Diseases ◽

10.4046/trd.1982.29.1.30 ◽

1982 ◽

Vol 29 (1) ◽

pp. 30-36

Author(s):

Song Hyun Nam ◽

Hyun Ha Park ◽

Re Hwe Kim ◽

Sung Koo Han ◽

Ye Won Kim ◽

...

Keyword(s):

Shape Analysis ◽

Pulmonary Diseases ◽

Flow Volume ◽

Maximal Expiratory Flow ◽

Volume Curve ◽

Flow Volume Curve ◽

Expiratory Flow

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Comparison of measures of forced expiration

Journal of Applied Physiology ◽

10.1152/jappl.1977.42.4.607 ◽

1977 ◽

Vol 42 (4) ◽

pp. 607-613 ◽

Cited By ~ 3

Author(s):

J. R. Ligas ◽

F. P. Primiano ◽

G. M. Saidel ◽

C. F. Doershuk

Keyword(s):

Obstructive Lung Disease ◽

Vital Capacity ◽

Mean Transit Time ◽

Forced Expiration ◽

Flow Volume ◽

Minimal Set ◽

Average Flow ◽

Maximal Expiratory Flow ◽

The Mean ◽

Independent Parameters

Theoretical relationships among a number of parameters were derived for idealized timed vital capacity (TVC) and maximal expiratory flow-volume (MEFV) curves to determine a minimal set of independent parameters. Normal pediatric subjects and those with cystic fibrosis were studied to verify these relationships experimentally. The average flow over the middle half (FEF25–75%) of the forced vital capacity (FVC) and flows at various exhaled percentages of the FVC (FEF50%, FEF75%), as well as moments of the TVC and MEFV curves were computed. From the TVC moments, a mean transit time (MTT) and an index of dispersion (ID) were also calculated. The minimum information needed to detect pulmonary mechanical changes associated with obstructive lung disease requires at least two reproducible measures: one related to the mean slope (e.g., FEF25–75%/FVC or MTT) and the other to the shape (e.g;, ID) of the effort-independent portion of the MEFV curve.

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