Effect of continuous positive airway pressure on breathing variability in early preterm lung disease

Objectives: In preterm infants, the application of nasal Continuous Positive Airway Pressure (nCPAP) improves lung function through several mechanisms and may interact with the control of breathing. Our aim was to evaluate the effect of increasing/decreasing nCPAP on gas exchange, breathing pattern, and its variability in preterm infants. Methods: Fifeteen infants with mild to moderate respiratory distress syndrome (RDS) were studied on the first day of life. Infants had a mean (SD) gestational age of 30+4 (3+4) weeks+day and body weight of 1405 (606)g. nCPAP was increased every 10min stepwise (0-4-8-10cmH2O) and then decreased every 20min (8-6-4-2cmH2O). At each step, vital parameters, oxygenation, and chest wall volume changes (optoelectronic plethysmography) were evaluated. Tidal volume (VT), inter-breath interval (IBI), end-expiratory lung volume (EELV) changes, and other breathing pattern parameters were computed breath-by-breath. The correlation properties of VT, IBI, and EELV were quantified by detrended fluctuation analysis, computing the scaling exponent α. Results: During nCPAP, oxygenation improved and VTdecreased significantly compared with no nCPAP. No significant changes in breathing pattern were observed between nCPAP levels. α of EELV was significantly higher off nCPAP than during nCPAP, suggesting that nCPAP helps stabilize EELV control mechanisms. Conclusions: In our population of preterm infants with mild to moderate RDS, in the first day of life, nCPAP improved gas exchange, VT, and EELV stability independent of nCPAP level.