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Identifying lung overdistention during mechanical ventilation by using volume‐pressure loops
Author(s) -
Fisher Joel B.,
Mammel Mark C.,
Coleman J. Michael,
Bing Denis R.,
Boros Stephen J.
Publication year - 1988
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.1950050104
Subject(s) - medicine , pulmonary compliance , mechanical ventilation , lung , lung volumes , respiratory system , respiratory physiology , positive airway pressure , airway , cardiology , nuclear medicine , anesthesia , obstructive sleep apnea
We measured the pulmonary mechanics of 23 mechanically ventilated neonates. Airway pressures, inspiratory and expiratory flows were simultaneously measured. Values for respiratory system mechanics were then derived from these data by using a personal computer and a special software program. Volume‐pressure (V‐P) loops and respiratory system compliance values were determined for representative mechanical breaths. Twelve infants had normal‐appearing V‐P loops. Eleven had V‐P loops characteristic of lung overdistention, showing decreasing changes in volume with progressive increases in pressure. To quantify this visual observation, we determined the change in compliance during the last 20% of inspiration (C 20 ). We then compared this value to the total compliance value for the entire breath (C) using the ratio C 20 /C. Mean values for C, C 20 , and C 20 /C were compared for the two patient groups. Total respiratory system compliance values were similar. C 20 values were decreased in those patients with V‐P loops showing overdistention. C 20 /C values were significantly decreased in those patients with V‐P loop evidence of overdistention. Patients with V‐P loop evidence of overdistention all had C 20 /C values less than 0.8. Those with normalappearing V‐P loops all had C 20 /C values greater than 1.0. The C 20 /C ratio appears to effectively quantitate visual V‐P loop evidence of lung overdistention during mechanical ventilation.