Cerebral and somatic oxygen saturation decrease after delayed sternal closure in children after cardiac surgery

Delayed sternal closure after pediatric cardiac surgery can temporarily impair cardiac output. Cerebral and somatic regional oxygen saturation measured by using near-infrared spectroscopy (NIRS) have been used as potential surrogates of cerebral and somatic mixed venous oxygen saturation. We hypothesized that cerebral and somatic regional oxygen saturation correlate with indicators of hemodynamic compromise after delayed sternal closure in children undergoing cardiac surgery.

We studied 36 postoperative children (median age, 10 days; range, 1-510 days) undergoing delayed sternal closure 3.7 +/- 2 days after cardiac surgery. Twenty-five had biventricular physiology, whereas 11 had single-ventricle physiology. Cerebral regional oxygen saturation, somatic regional oxygen saturation, and other physiologic parameters (hemodynamic data, respiratory data, blood gas analysis, lactate levels, and inotrope scores) were analyzed at 16 different time points 24 hours before and after sternal closure. One-way analysis of variance and the paired t test were used for statistical comparisons.

Cerebral and somatic regional oxygen saturation decreased after delayed sternal closure compared with preclosure levels (P = .02 and P = .01, respectively). Higher heart rate (P = .03), lactate levels (P = .02), and left atrial pressure (P = .001) were also noted, suggesting mild hemodynamic compromise. Arterial pressure and inotrope score were unchanged. Somatic regional oxygen saturation returned to preclosure levels earlier in the biventricular group than in the single-ventricle group, whereas cerebral regional oxygen saturation remained decreased after sternal closure with no evidence of return to preclosure levels during the observation period. Oxygen saturation, Pao(2), and Paco(2) levels were unaffected by sternal closure, although greater positive-pressure ventilation was required (P < .01), suggesting reduced lung compliance.

Cerebral and somatic regional oxygen saturation decrease after delayed sternal closure in children recovering from congenital cardiac surgery. These indices are in agreement with other physiologic indicators of cardiac performance, suggesting mild and transient hemodynamic compromise after sternal closure. Cerebral and somatic regional oxygen saturation monitoring might be a useful adjunct during delayed sternal closure.