Effect of forced-air warming system in prevention of postoperative hypothermia in elderly patients

Abstract

Background: Postoperative hypothermia in elderly patients is a well-known serious complication as it impairs wound healing, induces coagulopathy, increases the risk of blood loss, enhances oxygen consumption, and precipitates cardiac arrhythmias. We conducted this randomized controlled trial to evaluate the effect of a forced-air warming system on rewarming elderly patients undergoing total knee or hip arthroplasty. Methods: We recruited 243 elderly patients undergoing total knee or hip arthroplasty between May and December 2016. They were divided into three groups according to a computer-generated randomization table: group C (n = 78, rewarmed with only a regular blanket), group F1 (n = 82, rewarmed with a forced-air warming system set at 38°C), and group F2 (n = 83, rewarmed with a forced-air warming system set at 42°C). The nasopharyngeal temperature was recorded every 5 min for the first half hour, then every 10 min up to the end of the PACU (postanesthesia care unit) stay. The primary outcome was the rewarming time. The rewarming rate, increase in nasopharyngeal temperature (compared to the start of rewarming), hemodynamics, recovery time, and incidences of adverse effects were recorded. Results: No significant differences were found among the three groups in terms of the baseline clinical characteristics, use of narcotic drugs, intraoperative temperature, and hemodynamics ( P > .05). Compared with the elderly patients in groups C and F1, both the heart rate and mean arterial pressure of those in group F2 were significantly increased 20 min after arrival at the PACU ( P < .05). Patients in group F2 had the shortest rewarming time (35.89 ± 6.45 min, P < .001), highest rewarming efficiency (0.028 ± 0.001°C/min, P < .001), and fastest increased nasopharyngeal temperature among the three groups. Moreover, the elderly patients in group F2 had lower incidences of arrhythmia and shivering ( P < .05). Conclusions: The use of a forced-air warming system set at 42°C was shown to be the most effective way of rewarming elderly patients with postoperative hypothermia.

Effect of active forced air warming during the first hour after anesthesia induction and intraoperation avoids hypothermia in elderly patients

“…The reason accounted for the high risk of cardiac complications was the consequential increase in plasma norepinephrine concentrations, which promoted vasoconstriction with consequent hypertension and development of tachycardia. In our study, the incidence of arrhythmia, hypertension, hypotension,hypoxemia except sivering and sweating showed no difference between the three groups, which was accordance with the results in previous studies [ 2 , 18 ]. However, the disparity of shivering severity between Group L and Group LH or Group H existed in grade 0 merely.…”

“…Intraoperative hypothermia can be caused by general anesthesia, which is defined as a core body temperature below 36 °C [ 1 ]. If suitable measures aren’t taken in time, complications such as prolonged drug metabolism, postoperative shivering, wound infections, coagulopathy and cardiac arrhythmias and increase of hospital resources [ 2 ]. In order to maintain intraoperative normothermia during anesthesia, anesthetists have insisted on exploring warming period including warming patients before induction of anesthesia or during the operation, and warming instrument such as circulating-water garments, forced-air convection or continuous infusion of warmed liquids [ 3 ] , which are applied throughout the world.…”

“…However, the warming mode and duration time have been controversial according to different research previously. Some studies suggest that pre-warming reaches sufficient efficacy [ 12 ] and some support that forced-air warming system set at 42 °C is shown to be a more effective way of rewarming elderly patients [ 2 ]. Few researchers have focused on the efficacy of first hour warming after the induction of anesthesia.…”

Perioperative Management of Elderly patients (PriME): recommendations from an Italian intersociety consensus

“…Core temperature should be monitored in operations lasting more than 30 min, and warming should be used in older patients [72]. A forced-air warming system set at 42 °C is the most effective means of rewarming older patients with postoperative hypothermia [122], but a prewarmed infusion could also reduce the incidence of perioperative hypothermia and improve outcomes in geriatric patients [123].…”

The effects of warming fluid on hypothermia, blood transfusion in hip replacement

“…However, this ratio is lower in the group where liquids are warmed. Xu et al [15] recommended to administer warm intravenous or skin irrigation solutions and to increase the ambient room temperature, as well as, to use external warming devices to prevent hypothermia in the elderly. Liu et al [16] analyzed a total of 287 patients from 6 clinical studies and reported no statistical difference in thermal comfort, blood loss, or incidence of shivering and hypothermia between the air-free warming and forced-air warming groups.…”