Bi-level CPAP does not improve gas exchange when compared with conventional CPAP for the treatment of neonates recovering from respiratory distress syndrome

Aim We hypothesised that short-term application of bilevel nasal continuous positive airway pressure CPAP (SiPAP) compared with conventional nasal CPAP (nCPAP) at the same mean airway pressure in infants with persistent oxygen need recovering from respiratory distress syndrome would improve CO2 removal with no change in oxygen requirement.

Design Non-blinded, randomised, observational fourperiod crossover study.

Setting/population Level III NICU; low-birthweight infants requiring CPAP and oxygen while recovering from respiratory distress syndrome.

Methods Infants requiring nasal CPAP for >24 h prior to study enrolment, and fraction of inspired oxygen requirement (FiO₂) of 0.25-0.5, were randomised to either nCPAP or SiPAP. A crossover design with four 1 h treatment periods was used such that each infant received both treatments twice. Oxygen saturations (SaO₂), transcutaneous CO2 (tcCO₂) and vital signs were monitored continuously. Polysomnographic recordings were analysed for apnoea, bradycardia and oxygen desaturation.

Results Twenty low-birthweight infants receiving 0.3 ±0.04% supplemental oxygen on CPAP of 6 cm H₂O were studied at an average of 33 days of age (±23 days, SD). There were no differences in tcCO₂ or other physiological parameters except mean blood pressure, which was lower during nCPAP (52.3±8.3 vs 54.4±9.1 mm Hg; ±SD; p<0.01). No differences in short or prolonged apnoea, bradycardia or significant desaturation events were observed.

Conclusions At similar mean airway pressures, SiPAP does not improve CO2 removal, oxygenation or other studied physiological parameters with the exception of mean blood pressure, which was not clinically significant.