OBJECTIVES: High-flow regional cerebral perfusion (HFRCP) provides cerebral and somatic oxygen delivery through collateral vessels during aortic arch repair in small children; however, optimal flow conditions during HFRCP have not been established. We sought to identify markers of peripheral perfusion during HFRCP. METHODS: Between 2009 and 2016, in total 20 consecutive pediatric patients undergoing aortic arch repair with HFRCP were enrolled in this prospective, observational study. Median age was 20 days (range, 6-116 days); median body weight was 2.77 kg (range, 1.8-4.98 kg). Oxygen delivery ratio (Do2R) was calculated as the oxygen delivery during HFRCP divided by the oxygen delivery before HFRCP. Regional oxygen saturations on the forehead and on the thigh (rSo2T) were monitored during HFRCP, and postoperative creatinine kinase and lactate concentrations were measured as postoperative outcomes. Multivariate analyses were performed to clarify the effectiveness of Do2R and rSo2T as markers of peripheral perfusion during HFRCP. RESULTS: No deaths or neurologic impairments occurred. Multivariate analysis showed that the lowest rSo2T (P = .005) and cardiopulmonary bypass time (P = .012) predicted postoperative creatinine kinase concentration. Do2R was the only factor to predict postoperative lactate concentration (P < .001). Receiver operating characteristic analysis showed that Do2R less than 0.66 predicted risk of high postoperative lactate concentration (>5.0 mmol/L), with area under the curve of 0.95. CONCLUSIONS: For aortic arch repair in small children, rSo2T and Do2R during HFRCP are useful markers for predicting peripheral perfusion. Maintaining higher Do2R during HFRCP minimizes postoperative increases in lactate and creatinine kinase concentrations.