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The numerical analysis of pressure‐flow curves in infancy
Author(s) -
Stocks Janet,
Thomson Anne,
Silverman Michael
Publication year - 1985
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950010107
Subject(s) - medicine , airway resistance , flow (mathematics) , flow resistance , respiratory system , breathing , mathematics , anesthesia , cardiology , geometry
Lung resistance (R L ) and airway resistance (R aw ) were measured in 33 healthy and sick infants. Using strict criteria for quality control, calibrated pressure‐flow (P‐V) curves were produced with the aid of a computer so that resistance could be analyzed at several points over the breathing cycle. In a subgroup of 11 infants from whom simultaneous measurements were obtained, values of R L and R aw were comparable, suggesting that the tissue component may make only a minimal contribution to lung resistance in infants. For both R L and R aw , the P‐V relationship remained linear up to 50% maximum inspiratory flow in all infants. At other points of the respiratory cycle, there were marked changes in resistance, values calculated between points of mid‐isovolume or peak pressure being significantly higher than those measured over the linear portion of inspiratory flow. While no single value can accurately reflect the changes in respiratory resistance that occur during the breathing cycle, the authors suggest that for purposes of comparison, R L or R aw should be measured as the slope of the inspiratory loop from the origin up to 50% of maximum inspiratory flow. From a calibrated tidal pressure flow curve values of resistance over other portions of the breathing cycle can easily be determined.