Perioperative, local and systemic warming in surgical site infection: a systematic review and meta-analysis

Objective: Surgical site infection (SSI) is a common cause of postoperative morbidity. Perioperative hypothermia may contribute to surgical complications including increased risk of SSI. In this systematic review and meta-analysis, the effectiveness of active and passive perioperative warming interventions to prevent SSI was compared with standard (non-warming) care. Method: Ovid MEDLINE; Ovid EMBASE; EBSCO CINAHL Plus; The Cochrane Wounds Specialised Register, and The Cochrane Central Register of Controlled Trials were searched, with no restrictions on language, publication date or study setting for randomised controlled trials (RCTs) and cluster RCTs. Adult patients undergoing elective or emergency surgery under general anaesthesia, receiving any active or passive warming intervention perioperatively were included. Selection, risk of bias assessment and data extraction were performed by two review authors, independently. Outcomes studied were SSI (primary outcome), inpatient mortality, hospital length of stay and pain (secondary outcomes). Results: We identified four studies, including 769 patients. The risk ratio (RR) for SSI in warming groups was 0.36 [95% confidence interval (CI): 0.23, 0.56; p < 0.001]. Length of hospitalisation was 1.13 days less in warming groups [95% CI: -3.07, 5.33; p=0.600]. The RR for mortality in the warming groups was 0.77 [95% CI: 0.17, 3.43; p=0.730]. A metaanalysis for pain outcome could not be conducted. Conclusion: This review provides evidence in favour of active warming to prevent SSI, but insufficient evidence of active warming to reduce length of hospital stay and mortality. Benefits of passive warming remain unclear and warrant further research.