Pulmonary Function in Neonatal Respiratory Distress Syndrome : Effects of Two Modes of Non Invasive Ventilation

BACKGROUND: Despite of improved survival of premature infants, the incidence of long-term complications associated with ventilation-induced lung injury remains high. Non-invasive ventilation (NIV) is able to reduce the adverse effects of mechanical ventilation. High flow nasal cannula (HFNC) is emerging as an efficient form of NIV. OBJECTIVE: To compare the effects of nasal continuous positive airway pressure (NCPAP) and heated humidified HFNC on lung function in preterm newborns with respiratory distress syndrome (RDS). DESIGN/METHODS: A randomized crossover trial was performed on newborns with mild/moderate RDS, gestational age (GA) <34 weeks and postnatal age (PNA) <96 hours. Each neonate underwent both NCPAP (Infant Flow Driver System - EME) delivering 2, 4, 6 cmH2O and heated humidified HFNC (Precision Flow - Vapotherm) at 2, 4, 6 lpm. Sequences of these six, 15 minutes lasting ventilatory conditions were randomized. Lung volumes were measured using respiratory inductance plethysmography (Bioradio 150-CleveMed) calibrated with face-mask pneumotachography. An esophageal balloon estimated pleural pressure and a catheter-transducer system measured retropharyngeal pressure (Prp). Breathing pattern, lung mechanics, work of breathing (WOB), labored breathing index (LBI) and pressure time product (PTP) were calculated. ANOVA on Ranks for repeated measurements and Tukey test for multiple comparisons were performed. Differences were considered statistically significant for p<0.05. RESULTS: 20 newborns (mean GA 31±1 weeks, mean birth weight 1510±302g, mean PNA 53.5±27.5 hours) were enrolled. NCPAP was compared to HFNC selecting the conditions providing a Prp at end-expiration as close as possible to 2 and 4 cmH2O. At the same Prp, no significant difference was noticed in breathing pattern (Respiratory Rate, Tidal Volume, Minute Ventilation, Inspiratory and Expiratory Asynchrony Index), lung mechanics (Dynamic Resistance and Compliance), WOB (inspiratory, expiratory, elastic and resistive), LBI and PTP. A trend in higher values of WOB, LBI and PTP in HFNC was noticed. CONCLUSIONS: Our results show that NCPAP and HFNC have similar effect on breathing pattern, lung mechanics and WOB, providing comparable ventilatory support in preterm infants with RDS. Further studies are needed to identify possible differences between the two approaches on clinical long-term outcomes