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Validation of a nitrogen washout system to measure functional residual capacity in premature infants with hyaline membrane disease
Author(s) -
Miller Jason,
Law Amy B.,
Parker Robert A.,
Sundell Håkan W.,
Lindstrom Daniel P.,
Cotton Robert B.
Publication year - 1995
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.1950200611
Subject(s) - nitrogen washout , medicine , washout , functional residual capacity , hyaline , residual , measure (data warehouse) , disease , pathology , lung , data mining , lung volumes , algorithm , computer science
A multiple‐breath nitrogen washout system designed to measure lung volume in mechanically ventilated infants was validated by assessing three performance criteria: (1) accuracy of lung volume measurements in the presence of an endotracheal tube leak was assessed by comparing the measurements of functional residual capacity (FRC) in a mechanical lung model with and without airway leak; (2) in vivo accuracy was assessed in rabbits by comparing FRC measurements obtained by this system with measurements obtained by helium dilution; and (3) in vivo precision was assessed by analyzing measurements of FRC obtained in replicate measurements at different times in ventilator‐dependent premature infants with hyaline membrane disease. The average difference between the measurements of FRC in a mechanical lung model with airway leak and without leak was 3.0 ± 9.4% (mean ± SD, P > 0.2), and no difference was greater than 20%. There was a significant correlation between the measurements of FRC in rabbits by nitrogen washout and by helium dilution (r = 0.93, P < 0.000l), and 65.4% of the paired measurements were within 20% of their average. The 95% limits of agreement within pairs of measurements by the two techniques ranged from −4.0 to +6.5 mLkg. FRC measured by helium dilution was slightly higher (1.3 ± 2.7mUkg, P < 0.01) than FRC measured by nitrogen washout, and positive end‐expiratory pressure was a significant predictor of this difference (P < 0.01). The regression between the individual FRC measurements obtained in premature infants and the average of the other replicates was significant (6 > 0.98, P < 0.0001). The coefficient of variation was 12.3%. These findings provide further validation of this multiple‐breath nitrogen washout system for measuring FRC in premature infants during mechanical ventilation. Pediatr Pulmonol. 1995; 20:403–409 . © 1995 Wiley‐Liss, Inc.