Cerebral oxygen saturation before congenital heart surgery

Background. In congenital heart disease (CHD), neurologic abnormalities suggestive of hypoxia-ischemia are often apparent before cardiac surgery. To evaluate preoperative cerebral oxygenation, this study determined cerebral O2 saturation (ScO2) in CHD and healthy children. Methods. Ninety-one CHD and 19 healthy children aged less than 7 years were studied before surgical or radiologic procedures. Arterial saturation (SaO2) and ScO2 were measured by pulse-oximetry and near infrared cerebral oximetry. Cerebral O2 extraction (CEO2) was calculated (Saimage-ScO2). SaO2, ScO2, and CEO2 were compared among diagnoses. Multivariable regression was performed between ScO2 and clinical variables. Results. In healthy subjects, ScO2 (68% ± 10%) and CEO2 (30% ± 11%) were similar to patients with ventricular septal defect, aortic coarctation, and single ventricle after Fontan operation. ScO2 was significantly decreased in patients with patent ductus arteriosus (53% ± 8%), tetralogy of Fallot (57% ± 12%), hypoplastic left heart syndrome (46% ± 8%), pulmonary atresia (38% ± 6%), and single ventricle after aortopulmonary shunt (50% ± 7%), or bidirectional Glenn operation (43% ± 6%). CEO2 was significantly different only in patent ductus arteriosus (46% ± 8%) and hypoplastic left heart syndrome (38% ± 12%). In multivariable regression, only SaO2 was related to ScO2 (R = 0.63, p < 0.001). Conclusions. Cerebral oxygenation in CHD varies with anatomy and arterial saturation, and in some patients, it is very low compared with healthy subjects.