Effects of different ventilation methods during pulmonary surfactant administration on cerebral oxygen meta-bolism in preterm infants with neonatal respiratory distress syndrome

Objective To investigate effects of different ventilation methods during pulmonary surfactant(PS) administration on cerebral oxygen metabolism in preterm infants with neonatal respiratory distress syndrome. Methods Newborns met the inclusion criteria were enrolled into this study, and they were randomly divided into manual group and mechanical group.During PS administration, the proximal end of the tracheal tube was connected to a bag valve mask device in the manual group or a mechanical ventilator in the mechanical group.Brain near infrared spectroscopy monitoring was carried out to detect the cerebral oxygen saturation(ScO2), and the mean arterial blood pressure (MABP) was simultaneously recorded. Results For all 49 preterm infants, PS was administered to preterm infants with severe respi-ratory distress syndrome treated with mechanical ventilation, including 24 cases of manual ventilation and 25 cases of mechanical ventilation.The left cerebral ScO2 and correlation coefficient of ScO2 and MABP(rScO2-MABP) showed no difference in both groups before PS administration.During administration, ScO2 dramatically increased in both groups[manual group: (85.88±5.54)% vs.(77.31±5.40)%, t=5.521, P=0.000; mechanical group: (83.88±3.18)% vs.(76.53±4.38)%, t=6.741, P=0.000], and gradually decreased after administration, the level of ScO2 didn′t return to the baseline till the 2nd 5 minutes after PS administration[manual group: (79.25±3.02)% vs.(77.31±5.40)%, t=1.560, P=0.220; mechanical group: (78.59±3.45)% vs.(76.53±4.38)%, t=1.832, P=0.074]. The same trend of ScO2 change rate was shown simultaneously in both groups.The rScO2-MABP markedly increased during administration in both groups (manual group: 2.34±0.16 vs.1.86±0.21, t=9.022, P=0.000; mechanical group: 2.12±0.15 vs.1.87±0.21, t=4.810, P=0.000). The rScO2-MABP in mechanical group rapidly decreased to baseline during the 1st 5 minutes (1.84±0.18 vs.1.87±0.21, t=0.538, P=0.635) but went back to baseline in manual group during the 2nd 5 minutes(1.84±0.19 vs.1.86±0.21, t=0.350, P=0.809). Change rates of rScO2-MABP were markedly higher in manual group than those in mechanical group during the 1st 5 minutes (1.15±0.13 vs.1.00±0.15, t=4.943, P=0.000). Conclusions ScO2 could be affected transiently by PS administration with different methods of ventilation.The effect on cerebral autoregulation in mechanical group is shorter than that in manual group. Key words: Infant, premature; Neonatal respiratory distress syndrome; Pulmonary surfactant; Cerebral oxygen metabolism