Pellicer 2013.

Methods	Randomised controlled trial.
Participants	20 (11 intervention, 9 control) neonates undergoing cardiovascular surgery with CPB.
Interventions	Intervention: continuous intravenous infusion of levosimendan started intraoperatively and increased stepwise: dose 1 (0.1 µg/kg/min) starting immediately after central line placed and maintained for duration of surgical procedure, dose 2 (0.15 µg/kg/min) upon admission to neonatal ICU, dose 3 (0.2 µg/kg/min) starting after two hours of stability with dose 2; infusion stopped after 48 hours. Control: continuous intravenous infusion of milrinone started intraoperatively and increased stepwise: dose 1 (0.5 µg/kg/min) starting immediately after central line placed and maintained for duration of surgical procedure, dose 2 (0.75 µg/kg/min) upon admission to neonatal ICU, dose 3 (1 µg/kg/min) starting after two hours of stability with dose 2, until 48 hours after infusion started, afterwards infusion rate tapered according to attending physician.
Outcomes	Recorded until day 6 postsurgery: 1. Heart rate, breathing rate, central and peripheral temperature, arterial blood pressure, SaO2, cerebral and peripheral perfusion‐oxygenation (using NIRS instrument NIRO‐3000). 2. Blood gases, acid‐base status, CO‐oximetry, lactate, glucose, haemoglobin‐concentration, creatinine, N‐terminal probrain natriuretic peptide, troponine I, pro‐inflammatory and anti‐inflammatory factors.
Notes	Beyond 48 hours open study. Financial support of Orion Pharma Spanish Division for the pharmacokinetic studies (not part of outcome measures).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation list. Randomisation stratified by type of congenital heart defects and risk adjustment (using the congenital heart surgery method)
Allocation concealment (selection bias)	Low risk	Study nurse not involved in the clinical care of the infants was custodian of the allocation code.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Study medications prepared in identical opaque syringes, infusion tubes covered by aluminium foil, same infusion rates.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear risk due to unblinding of study after 48 hours, potential risk of detection bias after unblinding (study time point T3 and T4).
Incomplete outcome data (attrition bias) All outcomes	Low risk	All outcomes listed in the methods section reported.
Selective reporting (reporting bias)	Low risk	No incomplete reporting suspected.
Other bias	Low risk	Financial support of Orion Pharma Spanish Division for the pharmacokinetic studies (not part of outcome measures). Not deemed an important source of bias.