High continuous positive airway pressure in neonates: A physiological study

Abstract

Objective: We sought to evaluate physiological cardiorespiratory implications of high pressures (>8 cmH₂ O) on continuous positive airway pressure (CPAP) in preterm neonates.

Methods: Fifteen preterm neonates at postmenstrual age ≥32 weeks on CPAP 5 cmH₂ O were enrolled. Pressures were increased by 2 cmH ₂ O increments until 13 cmH ₂ O. At each increment, cardiac output, electrical diaphragmatic (Edi) activity, and clinical cardiorespiratory parameters were measured. Predefined cut-off values for changes in cardiorespiratory parameters were used as termination criteria. Data, presented as mean (SD), were compared using repeated measures analysis of variance.

Results: The mean GA, age at study, and weight of subjects were 27.4 (2.6) weeks, 58.5 (35.5) days, and 2.3 (0.6) kg, respectively. The median (IQR) time at each CPAP increment was 10 (5, 20) min. Cardiac output (mL/kg/min) at 5, 7, 9, 11, and 13 cmH ₂ O were not different at 295 (75), 290 (66), 281 (69), 286 (73), and 292 (58), respectively (P = 0.99). Edi values demonstrated a trend towards decline at 9 cmH ₂ O before rising again. No other cardiorespiratory parameter was different across CPAP levels; no subject met termination criteria.

Conclusion: High CPAP levels were well tolerated for short durations. Further physiological and clinical research is required on safety/efficacy in neonates with more severe lung disease, as well as its impact over longer durations.

Keywords: cardiac output; continuous distending pressure; electrical activity of diaphragm; noninvasive respiratory support; positive end-expiratory pressure.