Cerebral oximetry during infant cardiac surgery: evaluation and relationship to early postoperative outcome

We examined changes in cerebral oxygen saturation during infant heart surgery and its relationship to anatomic diagnosis and early outcome.

Regional cerebral oxygen saturation (rSO(2)) was measured by near-infrared spectroscopy in 104 infants undergoing biventricular repair without aortic arch obstruction as part of a randomized trial of hemodilution to a hematocrit of 25% vs 35%.

Before cardiopulmonary bypass (CPB), infants with tetralogy of Fallot had higher rSO(2) values compared to those with D-transposition of the great arteries (D-TGA) or ventricular septal defect (P < 0.001). During CPB cooling, low flow, and at the termination of CPB, D-TGA subjects had the highest rSO(2) values (P < 0.001). There were no significant associations between intraoperative rSO(2) and early postoperative outcomes after adjustment for diagnosis. In 39 D-TGA subjects with > or =5 min of deep hypothermic circulatory arrest (DHCA), there was no correlation between the rSO(2) (91% +/- 6%) or hematocrit (29.2% +/- 5.5%) at the onset of arrest and the rate of decline in rSO(2) during arrest.

Intraoperative rSO(2) varies according to anatomic diagnosis but accounts for very little of the variance in early outcome. As measured by frontal near-infrared spectroscopy, higher levels of hematocrit and current perfusion techniques appear to provide an adequate oxygen reservoir prior to relatively short periods of DHCA.