Pulmonary mechanics in healthy term neonates: variability in measurements obtained with a computerized system.
Using a commercially available computer-based analysis of ventilation and esophageal pressure (PeDs), we studied 11 healthy term neonates with serial pulmonary mechanics measurements during the first 3 days of life to determine the intrasubject variability of repeated measurements. Three consecutive pulmonary function tests were obtained before and after repositioning of the esophageal catheter, for a total of six measurements per day in each subject. The daily coefficient of variation for these 11 subjects ranged from 6% to 32% for respiratory rate; 6% to 27% for tidal volume; 3% to 28% for specific dynamic compliance, and 11% to 69% for pulmonary resistance. Repositioning the esophageal catheter did not produce significant differences in measurements of pulmonary mechanics (p greater than 0.05). We conclude that within a given subject, the maximum variability (mean + 2 SD) was 28% for specific dynamic compliance and 56% for pulmonary resistance. These intrasubject variability limits are important when one is interpreting pulmonary mechanics measurements in neonates before and after specific treatment, such as bronchodilators, diuretics, surfactant, or steroids.
Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City.
S K
SK
Gupta
J S
JS
Wagener
A
A
Erenberg
D000403:Airway Resistance; D003201:Computers; D004947:Esophagus / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008170:Lung Compliance; D008297:Male; D012119:Respiration / Q000502:physiology; D012143:Respiratory Physiological Phenomena; D013990:Tidal Volume / Q000502:physiology