Background and Goal of study: Postoperative shivering is relatively frequent complication of anesthesia. It is usually triggered by hypothermia after laparotomy. We had often experienced postoperative shivering in patients after osteotomy of maxilla and/or mandible for recent 7 years. Furthermore, it occurred even in normothermic patients during perioperative period. However, there are few reports about postoperative shivering after these surgery. In this study, we investigated the risk factors of postoperative shivering in oral-maxillofacial surgery retrospectively.

Materials and Methods: The study period was from April 2008 until September 2015. Anesthesia records of the patients who underwent osteotomy of maxilla and/or mandible were checked. The patients with preoperative fever (temperature>38°), with thyroid disease and receiving medication with the potential to influence thermoregulation, were excluded. Patient’s background (gender, age, height, weight), anesthesia time, operative time, fentanyl, remifentanil, fluid volume, urine volume, blood loss volume, agents for anesthetic maintenance, rectal temperature at the end of surgery and type of surgery were recorded in addition to the occurrence of postoperative shivering. Statistical analysis was performed using Fisher’s exact test, the χ2 test and stepwise logistic regression to determine the risk factors of postoperative shivering.

Results and Discussion: In this study, 233 cases were investigated. 24 patients (11.5%) had postoperative shivering. The occurrence of postoperative shivering was correlated with blood loss volume (Shivering group: 633.9±404.8ml vs Non-shivering group: 367.0±312.6ml) (p<0.01) and core temperature at the end of surgery (Shivering group: 37.2±0.6°C vs Non-shivering group: 37.5±0.5°C) (p<0.01). Two variables were associated with postoperative shivering. Rectal temperature at the end of surgery was the highest risk factor (odds ratio=2.560277; 95% CI=1.236774-5.327362), and the second was blood loss volume (odds ratio=0.997733; 95% CI =0.999-0998). In this study, mean rectal temperature was 37.2°C in patients with postoperative shivering, including 4 patients with rectal temperature more than 38.0°C. The thresholds of the thermoregulatory system might be increased by bleeding, hypovolemia and surgical stress during surgery. 

Conclusion: We should pay attention to the postoperative shivering not only in patients with hypothermia but also in patients with much bleeding.

Risk Factors of postoperative shivering after oral-maxillofacial surgery