Inadvertent perioperative hypothermia is an unintentional drop in core body temperature below 36°C. Intraoperative hypothermia can lead to serious clinical complications such as, myocardial ischemia, coagulopathy, immunosuppression, and surgical wound infection. Hypothermia develops easily during surgeries that require irrigation fluid, such as laparoscopic surgery and transurethral resection of the prostate. Although isothermic irrigation fluid was suggested to prevent perioperative hypothermia, it can be difficult to warm a large volume of irrigation fluid.

Re-distribution after induction of anesthesia is the most important cause of perioperative hypothermia. The extent of re-distribution is proportional to the gradient between the core and peripheral compartments. Pre-warming increases the heat content of the peripheral thermal compartment, reducing the gradient for redistribution. Recently, A recent-meta analysis suggested that as a single strategy, preoperative forced air warming had significant benefits than other warming methods. Also, it was reported that only 20 (or even 10) min of pre-warming mostly prevented patients from perioperative hypothermia under general anesthesia. However, few studies have examined whether short time pre-warming can reduce hypothermia due to a large amount of irrigation fluid during surgery under spinal anesthesia.

The purpose of this study is to assess whether the application of preoperative forced air warming set to high temperature (> 43°C) for brief period can prevent hypothermia or shivering during procedures requiring large volumes of cold irrigation.

Inclusion Criteria:

• Adult patients with ASA physical status I-III, aged 50 - 80 years, undergoing HoLEP under spinal anesthesia

Exclusion Criteria:

• preoperative body temperature of more than 37.2°C preexisting severe cardiovascular, respiratory and endocrinal disease on anticoagulant therapy