Trimble 1964.

Study characteristics
Methods	Type of study: single‐centre, parallel‐group randomised controlled trial. Full‐text paper Country: United Kingdom Dates of trial (start and end): not reported Follow‐up until: 24 hours postoperatively
Participants	Inclusions: 1. Adults (15 years or more) and children (under 15 years of age) undergoing cardiac surgery with CPB (analysed as separate groups) Exclusions: Not reported Age: Not reported Ethnicity: Not reported Gender: Not reported Operations: Not reported. Mix of elective and emergency patients not reported
Interventions	Adults Intervention arm: Postoperative transfusion of 2 units (500 ml) FFP after CPB and heparin neutralisation (n = 15) Comparator arm: Standard care (no comparator agent) (n = 25) Children Intervention arm: Postoperative transfusion of 1 unit (250 ml) FFP after CPB and heparin neutralisation (n = 6) Comparator arm: Standard care (no comparator agent) (n = 7)
Outcomes	Adults Primary: Postoperative blood loss 24 and 48 hours postoperatively Other outcomes: Not reported Children Primary: Postoperative blood loss 24 hours postoperatively Other outcomes: Return to theatre in study period
Notes	Adults and children were analysed separately
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The patients were divided into two groups by reference to a series of random numbers"
Allocation concealment (selection bias)	Unclear risk	Insufficient information about allocation concealment to permit judgement
Blinding of participants	Unclear risk	Insufficient information about blinding of participants to permit judgement
Blinding of personnel	Unclear risk	Personnel transfused FFP postoperatively to those randomised to the FFP group and, consequently, they will not have been blinded to the intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information about blinding of analysts to permit judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Results as presented do not state how many patients completed study but no patients are described as not completing the study
Selective reporting (reporting bias)	Low risk	All pre‐reported outcomes analysed
Equal use of co‐interventions in each arm	Unclear risk	Insufficient information about co‐interventions to permit judgement. In adults the mean perfusion time was lower in the group receiving FFP (87 minutes) than controls (131 minutes)
Balance of baseline factors	Unclear risk	Insufficient information about balance of baseline factors to permit judgement. In children the mean age was lower in the group receiving FFP (5.5 years) than controls (8.5 years)