Effect of nasal continuous positive airway pressure and Bi-phase positive airway pressure on oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome

Abstract

Objective To observe the effect of nasal continuous positive airway pressure (nCPAP) and Bi-phase positive airway pressure (BIPAP) on the oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome (NRDS). Methods After infusion of pulmonary surfactant into lung bilaterally, 116 cases with mild to moderate NRDS were treated with nCPAP(nCPAP group, n=75) and BIPAP(BIPAP group, n=41) respectively.Oxygen exchange indexes including arterial partial pressure of oxygen[pa(O2)], modified oxygenation index(P/F), alveolar- arterial oxygen tension difference(A-aDO2), respiratory index(RI), artery /alveolar oxygen partial pressure ratio[pa(O2)/pA(O2)] and pulmonary shunt fraction(Qs/Qt) were measured or calculated at 0 (before treatment), 2, 8 and 24 h after being treated with nCPAP or BIPAP. Results Six different oxygen exchange indexes of pa(O2), P/F, A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt in both groups didn't show statistical significance at 0 hour: pa(O2)(kPa)(6.1±0.6 vs 6.1±0.6, t=0.11, P>0.05), P/F(kPa)(15.59±1.45 vs 15.71±1.45, t=1.59, P>0.05), A-aDO2(kPa)(6.04±0.64 vs 6.24±0.69, t=1.59, P>0.05), RI(6.0±1.0 vs 6.2±1.1, t=1.35, P>0.05), pa(O2)/pA(O2) (0.24±0.02 vs 0.25±0.03, t=1.63, P>0.05)and Qs/Qt(%)(11.9±1.6 vs 11.6±1.6, t=1.10, P>0.05). A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt of BIPAP group had more improvement than those of nCPAP at 2 and 24 h, and oxygen exchange indexes at 2 h of BIPAP group and those of nCPAP group were: A-aDO2(kPa)(3.83±0.49 vs 4.24±0.67, t=18.26, P 0.05), P/F(28.49±3.17 vs 31.85±2.85, t=3.76.P>0.05)]. Nineteen cases in nCPAP group needed invasive mechanical ventilation, and only 3 cases in BIPAP group underwent the procedure; there was a significant difference (χ2=4.01, P<0.05). Oxygen exchange indexes in both groups were gradually improved from 2 h, 8 h to 24 h, but 22 deteriorated cases showed no improvement, who underwent invasive ventilation.Positive end-expiratory pressure(PEEP) positive airway pressure (EPAP) was (0.42±0.19) kPa in BIPAP group, and (0.56±0.23) kPa in nCPAP group(t=3.45, P<0.01). Conclusions 1.BIPAP and nCPAP can improve the ability of oxygen exchange in newborns with mild to moderate NRDS, but BIPAP is more effective than nCPAP, which can shorten the possibility of invasive ventilation and reduce the PEEP level.2.pa(O2), P/F, pa(O2)/pA(O2) and RI may be more suitable for evaluating oxygen exchange for neonatal NRDS. Key words: Neonatal respiratory distress syndrome; Noninvasive ventilation; Arterial partial pressure of oxygen; Oxygenation index; Alveolar arterial oxygen tension difference; Respiratory index; Arterial/alveolar oxygen partial pressure ratio; Pulmonary shunt fraction