See intervention description

RIPC was performed by applying a blood pressure cuff around the child's leg. The cuff was inflated to 40 mmHg above the systolic pressure in 4 cycles of 5 minutes. Every cycle of ischemia was followed by 5 minutes of reperfusion. The first RIPC cycle started after anesthesia induction when invasive arterial blood pressure was monitored. Appropriate cuff size was used choosing between four sizes. For reproducibility RIPC was performed on the right leg with only a few exceptions, when the leg was used for invasive catheters.

Categorized according to the RIFLE criteria (22): R= risk= increased p-creatinine * 1.5 and/or urine output < 0.5 ml/kg/hour for 6 hours, I= injury= increased p-creatinine * 2 and/or urine output < 0.5 ml/kg/hour for 12 hours, F= failure= increased p-creatinine * 3 or p-creatinine ≥ 350 µmol/L in the setting of an acute increase of at least 44 µmol/L and/or urine output < 0.3 ml/kg/hour for 24 hours or anuria for 12 hours, L= complete loss of renal function for > 4 weeks (need for dialysis for longer than 4 weeks), E= end-stage renal disease (need for dialysis for longer than 3 months).

Incidence of postoperative low blood pressure (below the age-reference level)

The highest postoperative daily dose (µg/kg//min) was used in the formula: IS = [(dopamine + dobutamine) × 1] + (milrinone × 10) + [(epinephrine + norepinephrine) × 100] to calculate the IS.