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Accurate, noninvasive quantitation of expiratory gas leak from uncuffed infant endotracheal tubes
Author(s) -
Knauth Alison,
Baumgart Stephen
Publication year - 1990
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.1950090113
Subject(s) - medicine , leak , anesthesia , endotracheal tube , mechanical ventilation , biomedical engineering , intubation , environmental science , environmental engineering
Accurate measurement of expiratory gas leak from uncuffed infant endotracheal tubes is an important requirement for evaluating the rates of metabolic gas exchange by indirect calorimetry in neonates receiving mechanical ventilation. The present study reports a new, noninvasive technique for the efficient collection and analysis of expiratory gases leaked from a closed‐circuit metabolic monitoring system recently described. A loose‐fitting face mask is placed over the infant's endotracheal appliance and air is entrained from the mask cavity at 100 mL/min for CO 2 analysis by infrared capnometry. In vitro calibration of this apparatus demonstrates a relative error of less than 5% of simulated endotracheal tube leak. In vivo application to metabolic rate assessment (using the MGM Jr. metabolic cart) in 12 intubated, ventilated infants ranging from 1.56 to 4.07 kg study weight demonstrated endotracheal tube leaks from 0.49 to 7.40% of net CO 2 production, which ranged 10.67 to 70.91 mL/min (or mean 8.22 ± 0.93 SEM mL/kg/min). The magnitude of tube leakage of mixed expiratory gases could not be predicted from endotracheal tube diameter, ventilator settings, or infant activity or posture. As new instrumentation becomes available to measure the rates of metabolic gas exchange in intubated infants, systematic evaluation of uncuffed endotracheal tube gas leaks becomes critical. Pediatr Pulmonol. 1990; 9:55–60 .