Perrins 1967.

Methods	Randomised clinical trial Study period: not stated
Participants	Inclusion criteria: every patient with split skin grafting Exclusion criteria: infants Baseline wound size: not stated Mean age (SD): not stated HBOT n = 24 Control n =24 Total number of patients = 48 Duration of follow‐up: 7 days Setting: Burns Unit, Queen Mary's Hospital, Roehampton, London, United Kingdom
Interventions	Intervention: HBOT treatment in a Vicker's clinical transparent pressure chamber, sessions of 100% O2 at 2 ATA for 2 hours, 1 day twice and the next 3 days once Comparison: usual care, clarification of usual care was not stated All cases had closed dressings of paraffin gauze, cotton wool and bandages applied to the operation and donor sites
Outcomes	Graft survival (defined as at least 95% take) at day 7
Notes	Location: Queen Mary's Hospital, Roehampton, London, United Kingdom Setting: Burns Unit Financial support: not stated Estimating patches is not a reliable and validated outcome measurement
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were allotted randomly to treatment or control groups" Comment: insufficient information about the sequence generation process
Allocation concealment (selection bias)	Unclear risk	Comment: the method of concealment is not described
Blinding (performance bias and detection bias) Care provider blinding	Low risk	Quote: "routine surgery was performed by the surgeon, who did not know if the case was subsequently to be treated". Comment: probably done; surgeon is blinded
Blinding (performance bias and detection bias) Outcome assessor blinding	Unclear risk	Comment: the surgeon who performed the operation was blinded, but it is not clear whether he was also the outcome assessor
Blinding (performance bias and detection bias) Participant blinding	High risk	Comment: only the surgeon who performed the operation was blinded
Incomplete outcome data (attrition bias) Was drop out rate described and acceptable	Low risk	Comment: there were no drop‐outs and all patients were assessed at the 6‐day follow‐up time point.
Incomplete outcome data (attrition bias) ITT analysis	High risk	Comment: 2 grafts failed completely in the treated group. These 2 cases were excluded from analysis, on the grounds that a successful 'take' could not be expected.
Selective reporting (reporting bias)	High risk	Comment: no protocol available, but percentage wound healing was measured at day seven with multiple sub‐endpoints. This increases the risk of a type 1 error.
Other bias	Unclear risk	Comment: baseline comparability not stated; same treatment apart from intervention