OBJECTIVEA prospective study was conducted to probe into the relationship between arterial oxygen partial pressure (PaO2) and brain injury during cardiopulmonary bypass (CPB) in infants with cyanotic congenital heart disease (CHD).

METHODEnrolled in the study were 45 cyanotic infants, who were less than three years old and underwent corrective cardiac surgery from August 1(st), 2010 to January 31(st), 2011 at Guangdong General Hospital. All the infants had a pulse oxygen saturation (SpO2) lower than 85% and were randomly allocated into three groups by a specific computer program. In controlled group 1 (G1 group), PaO2 levels were controlled at 80 - 120 mm Hg (1 mm Hg = 0.133 kPa) during CPB; in controlled group 2 (G2 group), PaO2 levels at 120 - 200 mm Hg during CPB; while in uncontrolled group (G3 group), PaO2 levels were at 200 - 400 mm Hg during CPB. Blood samples were collected just before starting CPB, at the end of CPB, and at 3 h, 5 h, and 24 h after CPB (T1, T2, T3, T4, T5) for the determination of serum concentrations of protein S100β, neuron specific enolase (NSE), and adrenomedullin (ADM) by ELISA.

RESULTProtein S100β rose significantly after starting CPB. In group G3, it reached a peak of (699 ± 139) ng/L by the end of CPB, significantly higher than those in groups G1 and G2 [(528 ± 163) ng/L and (585 ± 155) ng/L], and was positively correlated with PaO2 levels (r = 0.526, P < 0.01). NSE levels of group G1 were continuously rising after starting CPB and reached significantly high levels at 3 h or 5 h after CPB [(12.2 ± 3.4) µg/L and (12.3 ± 3.7) µg/L], while those of group G2 rose significantly during CPB [(10.9 ± 4.8) µg/L] and even higher at 3 h or 5 h after CPB [(12.6 ± 5.1) µg/L and (13.2 ± 5.4) µg/L]. NSE levels of group G3 rose significantly during CPB and maintained at a high level [(12.2 ± 5.7) µg/L] afterwards. There was no significant difference in serum ADM concentrations among different time points in each group and among these three groups. All the infants were discharged from the hospital without any obvious nervous symptom and sign.

CONCLUSIONHigh PaO2 during CPB in infants with CHD might cause an increase of serum protein S100β and NSE, indicating that brain injury might become worse with a higher PaO2 and might be positively correlated with PaO2 during CPB.