Resistant fabric warming is a viable alternative to forced-air warming to prevent inadvertent perioperative hypothermia during hemiarthroplasty in the elderly

Background Surgical site infection (SSI) is associated with inadvertent perioperative hypothermia (IPH). This can be prevented by active patient warming. However, results from comparisons of warming techniques are conflicting. They are based mostly on elective surgery, are from small numbers of patients, and are dominated by the market leader, forced-air warming (FAW). Furthermore, the definition of hypothermia is debatable and systematic reviews of warming systems conclude that a stricter control of temperature is required to study the benefits of warming. Aim To analyse core temperatures in detail in a large subset of elderly patients who took part in a randomized trial of patient warming following hemiarthroplasty who had received constant zero-flux thermometry to record their temperature. Methods Regression models with a fixed effect for warming group and covariates related to temperature were compared for 257 participants randomized to FAW or resistant fabric warming (RFW) from a prior clinical trial. Findings Those in the RFW group were -0.08°C cooler and had a cumulative hypothermia score -1.87 lower than those in the FAW group. There was no difference in the proportion of hypothermic patients at either <36.5°C or <36.0°C. Conclusions This is the first study to provide accurate temperature measurements in patients undergoing a procedure predominantly under regional rather than general anaesthetic. It shows that RFW is a viable alternative to FAW for preventing IPH during hemiarthroplasty. Further studies are needed to measure the benefits of patient warming in terms of clinically important outcomes.