Title: Impact of unintentional postoperative hypothermia on patient-centred outcomes after general anaesthesia

Background and Goal of Study: Unintentional postoperative hypothermia is a frequent occurrence that can lead to several complications, adversely affecting the patient´s outcome. This study aims to assess the incidence and impact of hypothermia on patient-centred outcomes after elective surgery. 

Materials and methods: After approval by the institutional ethics committee, an observational, prospective study was performed in patients scheduled for elective surgery under general anaesthesia. Were studied 208 patients admitted to the Post Anaesthetic Care Unit (PACU) after plastic, gynaecologic, urologic and general surgery. Exclusion criteria were: age< 18 years and inability to give informed consent or to speak Portuguese language fluently. Patients' demographics and perioperative characteristics were evaluated. Hypothermia was defined as an auricular temperature< 35ºC at PACU admission. Quality of recovery (QoR) 24h after surgery (D1) was evaluated by the Quality of Recovery 15 (QoR-15) score. The Postoperative Quality Recovery Scale (PQRS) Portuguese version was used at baseline (D0) and after surgery at minute 15 (T15), 40 (T40) and days 1 (D1) and 3 (D3) evaluating recovery in 5 domains. The 12-itens WHODAS questionnaire was used to measure Disability at D0. The Mann-Whitney test, Chi-square or Fisher's exact test were used for comparisons. 

Results and discussion: Hypothermia was present in 39 (20%) of the 192 patients included. Patients with hypothermia were older (61 vs. 53 median years, p=0.037) and had a median low Body Mass Index (25 vs. 27, p=0.044). No differences were found between groups concerning duration of anaesthesia and length of PACU stay. The median scores for total QoR-15 and for every QoR-15 item were similar. Complete recovery in the emotive domain (anxiety and depression) of PQRS was significantly more frequent in hypothermic patients at D1 (68% vs. 43%, p=0.005) and D3 (67% vs. 40%, p=0.005). Complete recovery of activities of daily living was less frequent in hypothermic patients at D1 (30% vs. 48%, p=0.048). Recovery of cognitive domain was worst for hypothermic patients at T40 (0% vs. 22%, p=0.036). Hypothermic patients were not more frequently considered disable by WHODAS at D0. 

Conclusion(s): PQRS was able to denote important patient-centred differences in outcome after surgery in patients with hypothermia while QoR-15 was not able to show differences. Patients with hypothermia were older and leaner but were not more disable.