Age-dependent cerebral oxygenation and brain injury in pediatric cardiac surgery: vulnerability of infants aged ≤6 months.

BACKGROUND: Despite the growing use of regional cerebral oxygen saturation (rScO2) monitoring in pediatric cardiac surgery, whether age affects perioperative rScO2 trajectories or modifies the association between rScO2 and organ injury remains unclear. In this study, age-specific rScO2 patterns were delineated, and whether age modified the association between rScO2 nadir and postoperative neurological and myocardial injury biomarkers was evaluated. METHODS: This prospective cohort study included 104 children who underwent congenital heart surgery and whose ages were ≤6 months (n=47), 6-12 months (n=28), and >12 months (n=29). Perioperative rScO2 was continuously monitored at five time points: pre-cardiopulmonary bypass (CPB), CPB, aortic cross-clamp (ACC), post-return of spontaneous circulation (ROSC), and postoperative day 2 (POD2). Linear mixed-effects models with age-group-by-time interactions were used to test differences in rScO2 trajectory between age groups. Multivariable linear regression was used to assess the association between the rScO2 nadir and peak biomarkers levels (NSE, GFAP, S100β, cTnI, CK-MB, NT-proBNP), with age interactions included, followed by age-stratified analyses. RESULTS: Perioperative rScO2 followed a U-shaped pattern across all age groups, with the ≤6-month group consistently exhibiting the lowest levels. Compared with infants >12 months, those ≤6 months exhibited greater decreases in rScO2 during both CPB (β>12-month*CPB = 4.17, 95% CI [0.47, 7.87], P = 0.027) and ACC (β>12-month*ACC = 4.75, 95% CI [1.05, 8.45], P = 0.012). Significant age interactions for the rScO2 nadir-NSE association were observed for the 6-12 months group (β = 0.41, 95% CI [0.05, 0.77], P=0.027) and the >12-month group (β = 0.43, 95% CI [0.01, 0.84], P=0.044) relative to the ≤6-month reference. In age-stratified analyses, the rScO2 nadir was significantly inversely associated with peak NSE only in the ≤6-month group (β = -0.27, 95% CI [-0.48, -0.07], P=0.001). No significant associations were found between the rScO2 nadir and other neurological biomarkers (GFAP, S100β) or any myocardial biomarkers (CK-MB, cTnI, NT-proBNP) across age groups. CONCLUSIONS: Age affects both rScO2 trajectories and their association with peak NSE. Infants ≤6 months exhibited the lowest rScO2 values and a significant inverse association between the rScO2 nadir and peak NSE, supporting the need for more intensive monitoring in this subgroup.