Effect of Pre-warming on Perioperative Hypothermia During HoLEPunder Spinal Anesthesia

Effect of Pre-warming on Perioperative Hypothermia and Shivering During Holmium Laser Enucleation of the Prostate (HoLEP) Under Spinal Anesthesia

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.

On arrival at the preoperative care unit, assignments were determined using an opaque sealed envelope opened by investigator with no clinical involvement in the study. In the pre-warming group, the forced-air blanket (COVIDIEN™ WarmTouch™ Full Body/Multi Access Blanket, Covidien Ilc, Mansfield, MA, USA) was positioned over the whole body except head and neck, covered by cotton blanket. Forced air warmer (COVIDIEN™ WarmTouch™ WT6000 Warming Unit, Covidien Ilc, Mansfield, MA, USA) was set to 'high level' (45℃) during 20 min. During the warming procedure, patients were asked every 5 min about their thermal comfort; if they felt overheated, the warmer was lowered to 41℃

taken in the same ear using an infrared tympanic thermometer (ThermoScan IRT 1020; Braun, Germany), and the highest reading from three consecutive measurements was recorded.

Hypothermia defined as a core temperature less than 36.0°C in according to the current guideline. The number of patients who became hypothermic at each time was recorded.

at baseline (preoperative care unit), on arrival at the OR, every 10 minutes after spinal anesthesia, and on admission to PACU 1 hour

graded using 4 point scale (0 = no shivering; 1 = shivering localized to the core and neck; 2 = shivering including the upper extremities; and 3 = total body shivering)

on arrival at the OR, at every 30 minutes after spinal anesthesia, on admission to PACU, and then every 30 minutes for 1 hour.

evaluated using a numeric rating scale: 0 was defined as 'extremely cold', 5 as 'thermally neutral', and 10 as 'extremely hot'

on arrival at the OR, at every 30 minutes after spinal anesthesia, on admission to PACU, and then every 30 minutes for 1 hour.

taken in the same ear using an infrared tympanic thermometer (ThermoScan IRT 1020; Braun, Germany), and the highest reading from three consecutive measurements was recorded.

at baseline (preoperative care unit), on arrival at the operation room, every 30 minutes after spinal anesthesia

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

Jun JH, Chung MH, Kim EM, Jun IJ, Kim JH, Hyeon JS, Lee MH, Lee HS, Choi EM. Effect of pre-warming on perioperative hypothermia during holmium laser enucleation of the prostate under spinal anesthesia: a prospective randomized controlled trial. BMC Anesthesiol. 2018 Dec 22;18(1):201. doi: 10.1186/s12871-018-0668-4.