NICE guidelines for inadvertent peri‐operative hypothermia

Abstract

We would like to report on our experience of introducing National Institute for Health and Clinical Excellence (NICE) guideline ‘The management of inadvertent perioperative hypothermia in adults’ [1] into our fast-track primary arthroplasty centre. We have conducted four audits of temperature management covering 353 patient episodes (the first two before the NICE guideline release). The overall impact of the guideline on our practice has been positive, such that in our last audit, 99% of patients were not hypothermic at any time. We have, however, encountered two key problems with the guideline. Our first concern is the relationship between pre-operative warming and not inducing anaesthesia below a certain temperature. Since NICE has used the same temperature <36 °C as the cut-off for both interventions, a trivial drop of 0.1 °C could result in the somewhat drastic measure of not inducing anaesthesia, without the opportunity to use an active measure to avoid this. In our experience, whilst the mean temperature of the population might remain the same between the ward and anaesthetic room, very few patients remain at exactly the same temperature; i.e. about half experience a drop in temperature. We feel there should be clear water between the temperature for active pre-operative warming and the cut-off for not inducing anaesthesia. The second issue relates to the surprisingly complex subject of defining normal temperature and therefore hypothermia. The difficulty for NICE is that there is enormous variability in normal temperature once age, gender, time of day, menstrual cycle and, most importantly, the method and site of measurement have been taken into account [2, 3]. We also recognise that NICE has had to take into account the views of stakeholders and the wider NHS procurement process when considering methods of measuring temperature. Nevertheless, the definition of normal temperature and hypothermia, and in particular how they relate to different measurement modalities, are fundamental to successful implementation of this guideline and should have been clearly and comprehensively communicated in the executive summary. Unfortunately, NICE has skirted around this subject in the summary and even within the full guidance, there is a failure to tackle the subject of monitoring adequately, as recognised by Harper et al. [4]. Using only the executive summary it would be easy to misinterpret audit results leading to inappropriate conclusions about performance and, if the indication to not induce anaesthesia is observed, significant theatre inefficiency (Table 2). A correction factor should be applied to non-core temperature measurements, which can be found on page 202 of the full guideline [1].