Lung resistance and elastance in spontaneously breathing preterm infants: effects of breathing pattern and demographics

• Published in: Journal of applied physiology (1985) 2000-03, Vol.88 (3), p.997-1005
• Main Authors: Pandit, Paresh B, Pyon, Kee H, Courtney, Sherry E, England, Sandra E, Habib, Robert H
• Format: Article
• Language: English
• Subjects: Airway Resistance - physiology; Elasticity; Female; Humans; Infant, Newborn; Infant, Premature - physiology; Lung Compliance - physiology; Male; Models, Biological; Multivariate Analysis; Respiratory Mechanics - physiology
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.88.3.997

1  Department of Pediatrics, The Children's Regional Hospital at Cooper Hospital and Robert Wood Johnson Medical School, Camden 08103; 2  Department of Pediatrics, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901; and 3  Department of Pediatrics, Mercy Children's Hospital at St. Vincent Mercy Medical Center, Medical College of Ohio, Toledo, Ohio 43608 Reported values of lung resistance (R L ) and elastance (E L ) in spontaneously breathing preterm neonates vary widely. We hypothesized that this variability in lung properties can be largely explained by both inter- and intrasubject variability in breathing pattern and demographics. Thirty-three neonates receiving nasal continuous positive airway pressure [weight 606-1,792 g, gestational age (GA) of 25-33 wk, 2-49 days old] were studied. Transpulmonary pressure was measured by esophageal manometry and airway flow by face mask pneumotachography. Breath-to-breath changes in R L and E L in each infant were estimated by Fourier analysis of impedance (Z) and by multiple linear regression (MLR). R L MLR (R L MLR  = 0.85   × R L Z 0.43; r 2  = 0.95) and E L MLR (E L MLR  = 0.97 × E L Z  + 8.4; r 2  = 0.98) were highly correlated to R L Z and E L Z , respectively. Both R L (mean ± SD; R L Z  = 70 ± 38, R L MLR  = 59 ± 36 cmH 2 O · s ·   l 1 ) and E L (E L Z  = 434 ± 212, E L MLR  = 436 ± 210 cmH 2 O/l) exhibited wide intra- and intersubject variability. Regardless of computation method, R L was found to decrease as a function of weight, age, respiratory rate (RR), and tidal volume (V T ) whereas it increased as a function of RR · V T and inspiratory-to-expiratory time ratio (T I /T E ). E L decreased with increasing weight, age, V T and female gender and increased as RR and T I /T E increased. We conclude that accounting for the effects of breathing pattern variability and demographic parameters on estimates of R L and E L is essential if they are to be of clinical value. Multivariate statistical models of R L and E L may facilitate the interpretation of lung mechanics measurements in spontaneously breathing infants. impedance; multiple linear regression; frequency dependence; amplitude dependence