Russell 2000.

Study characteristics
Methods	Study objective: to determine the efficacy and safety of a multi‐cell pulsating dynamic mattress system in comparison with conventional management for the prevention of pressure ulcers in the operative and postoperative period in patients having cardiovascular surgery. Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 7 days Number of arms: 2 Single centre or multi‐site: single centre Study start date and end date: not described Setting: hospital
Participants	Baseline characteristics Inclusion criteria: be 18 years of age or older and be scheduled for cardiovascular surgery with general anaesthesia for at least 4 hours with an actual operative time of 3 hours or more Exclusion criteria: had a pressure ulcer at the baseline visit Sex (M:F): 75:23 in multi‐cell pulsating dynamic mattress; 75:25 in conventional management Age (years): mean 65.2 (SD 10.9) in multi‐cell pulsating dynamic mattress; 65.2 (10.6) in conventional management Baseline skin status: mean Knoll score 3.6 (SD 1) in multi‐cell pulsating dynamic mattress; 3.8 (1) in conventional management; no pressure ulcer Group difference: no difference Total number of participants: n = 198 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Multi‐cell pulsating dynamic mattress Description of interventions: multi‐cell pulsating dynamic mattress system (MicroPulse Inc., Portage, Mich.) ... comprised of a thin pad with more than 2,500 small air cells enclosed in a fluid‐proof cover. The air cells are arranged in rows so that the patient is supported by 50% of the cells (the inflated cells) at any given time ... With a cycle time of less than 5 minutes ... on the system in the operating room and in their hospital room until discharge from the hospital or for a maximum of 7 days post‐surgery. NPIAP S3I classification: powered, alternating pressure (active) air surface Co‐interventions: not described Number of participants randomised: n = 98 Number of participants analysed: unspecified Conventional management Description of interventions: the use of a gel pad (Action Pad®, Action Products, Inc.) in the operating room and then a standard hospital mattress on the hospital bed (the Hill‐Rom Centra with 6‐inch foam overlay in the critical care recovery unit; and the Hill‐Rom Century with 4‐inch foam overlay in the cardiac ward) NPIAP S3I classification: non‐powered, reactive gel surface; non‐powered, reactive foam surface; applied sequentially Co‐interventions: not described Number of participants randomised: n = 100 Number of participants analysed: n = 100
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: day 7 Reporting: partially reported Measurement method (e.g. scale, self‐reporting): defined and staged using the National Pressure Ulcer Advisory Panel scoring system Definition (including ulcer stage): the occurrence of pressure ulcers at any time within 7 days of surgery Dropouts: not described Notes (e.g. other results reported): 2 in multi‐cell pulsating dynamic mattress (both grade 1); 7 of 100 in conventional management (5 grade 1, 1 grade 2, 1 grade 3) (2.2% vs. 7%, P = 0.170) Time to pressure ulcer development Reporting: not reported Support‐surface‐associated patient comfort Reporting: not reported All reported adverse events using allocated support surfaces Reporting: partially reported Notes: approximately 1/2 of all participants in each group reported adverse events, with no differences between groups reported. All adverse events were related to the participant’s condition; none were related to the multi‐cell pulsating dynamic mattress system or conventional management support system. Health‐related quality of life (HRQOL) Reporting: not reported Cost‐effectiveness Reporting: not reported
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Before surgery, patients were randomly assigned to either the multi‐cell pulsating dynamic mattress system or conventional management. Randomization was done blindly by using a sealed opaque envelope that contained the randomization information (i.e. multi‐cell pulsating dynamic mattress system vs. conventional management)" Comment: unclear risk of bias because randomisation method is not described.
Allocation concealment (selection bias)	Unclear risk	Quote: "Randomization was done blindly by using a sealed opaque envelope that contained the randomization information (i.e. multi‐cell pulsating dynamic mattress system vs. conventional management)" Comment: unclear risk of bias because randomisation method is not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Outcome group: primary outcome Comment: high risk of bias because it is unlikely that participants were blinded, though no information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome group: primary outcome Quote: "Patients were examined immediately post‐surgery for pressure ulcers, including number, stage (I to IV), size (area), location, and appearance. Patients were assessed daily for ... presence of pressure ulcers. A skin risk assessment was performed on days 1, 4, and 7 and on other days if a change in status was noted. Adverse events and concomitant medications were recorded daily" Comment: unclear risk of bias because information on outcome assessment is insufficient for a proper judgement.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: primary outcome Quote: "Baseline characteristics and safety were evaluated for all randomised patients (i.e. intent‐to‐treat sample) ... The intent‐to‐treat sample included all patients who signed consent forms and who were placed either on a multi‐cell pulsating dynamic mattress system or on a conventional mattress and had at least 1 day of observation post‐surgery ... An evaluable sample of patients was defined as patients who signed consent forms, had a surgery length of at least 3 hours, and had a minimum of 3 days of observation post‐surgery ... One analysis included the intent‐to‐treat sample (multi‐cell pulsating dynamic mattress system, n = 89; conventional management, n = 96)" Comment: low risk of bias because of the use of intention‐to‐treat (ITT) analysis.
Selective reporting (reporting bias)	Low risk	Comment: the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	Comment: the study appears to be free of other sources of bias.