The Role of Regional Oxygen Saturation Using Near-Infrared Spectroscopy and Blood Lactate Levels as Early Predictors of Outcome After Pediatric Cardiac Surgery

Background: The purpose of the study was to evaluate the association between regional oxygen saturation (rSO(2)) desaturation score (calculated by multiplying the rSO(2) < 50% by time in seconds the preoperative baseline value) measured with near-infrared spectroscopy and the peak of lactate with postoperative major morbidities in pediatric patients who undergo cardiac surgery. Methods: We retrospectively analyzed the postoperative course of 152 patients between January 2012 and December 2013, for whom we continuously monitored cerebral rSO(2) using near-infrared spectroscopy and serial arterial blood lactate levels for at least 48 hours. Results: The median age at surgery was 128 days (interquartile range [IQR], 17-537 days). Thirty-nine patients had a single ventricle physiology (26%) and 135 patients (89%) required the use of cardiopulmonary bypass (median time of 130 minutes; IQR, 93-172 minutes). Median postoperative peak lactate level was 3 mmol/L (IQR, 2-5.3 mmol/L); 52 patients (34%) had a postoperative lactate level > 4.6 mmol/L. The median postoperative rSO(2) desaturation score was 157 (IQR, 0-2050); 62 patients (41%) had an rSO(2) desaturation score > 345. Fifty-seven patients (37%) had postoperative major morbidities. Using a multivariable regression model only rSO(2) desaturation score > 345 was independently associated withmajor morbidities after surgery (odds ratio, 27.26; 95% confidence interval, 10.18-73.00). The proportion of patients with an rSO(2) desaturation score > 345 within 240 minutes after surgery was higher than the rate of those who showed a peak of lactate > 4.6 mmol/L (84% vs 59%; P = 0.05). Conclusions: The postoperative rSO(2) desaturation score has a stronger association with major postoperative morbidities than lactate and it also provides an earlier warning sign of hemodynamic or metabolic compromise.