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

Despite the growing use of regional cerebral oxygen saturation (rScO 2 ) monitoring in pediatric cardiac surgery, whether age affects perioperative rScO 2 trajectories or modifies the association between rScO 2 and organ injury remains unclear. In this study, age-specific rScO 2 patterns were delineated, and whether age modified the association between rScO 2 nadir and postoperative neurological and myocardial injury biomarkers was evaluated. 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 rScO 2 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 rScO 2 trajectory between age groups. Multivariable linear regression was used to assess the association between the rScO 2 nadir and peak biomarkers levels (NSE, GFAP, S100β, cTnI, CK-MB, NT-proBNP), with age interactions included, followed by age-stratified analyses. Perioperative rScO 2 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 rScO 2 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 rScO 2 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 rScO 2 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 rScO 2 nadir and other neurological biomarkers (GFAP, S100β) or any myocardial biomarkers (CK-MB, cTnI, NT-proBNP) across age groups. Age affects both rScO 2 trajectories and their association with peak NSE. Infants ≤6 months exhibited the lowest rScO 2 values and a significant inverse association between the rScO 2 nadir and peak NSE, supporting the need for more intensive monitoring in this subgroup.