The effect of 10 minutes of prewarming for prevention of inadvertent perioperative hypothermia: comparison with 30 minutes of prewarming

BACKGROUND: At least 30 minutes of pre-warming has been recommended for the prevention of redistribution hypothermia. However, it has been reported that less than 30 minutes of pre-warming is also effective. The aim of this study was to evaluate the ability of 10 minutes of pre-warming to prevent inadvertent perioperative hypothermia. Results were compared with 30 minutes of pre-warming. METHODS: In this prospective randomized study, 59 patients scheduled for elective surgery less than 120 minutes under general anesthesia were divided into 2 groups: the first group was pre-warmed for 10 minutes (n = 30), the second group for 30 minutes (n = 29). The patients were pre-warmed for 10 or 30 minutes in the pre-anesthetic area using a forced-air warmer. When the patients' body temperatures decreased below 36℃, we warmed them with a forced-air warmer intraoperatively and postoperatively. Body temperatures were recorded during perioperative periods. Shivering and thermal comfort were evaluated in the pre-anesthetic area and post-anesthesia care unit. RESULTS: The incidence of intraoperative and postoperative hypothermia were not significantly different (P > 0.05). However, the temperatures were higher in the 30 minute group from the post-warming time to 90 minutes after anesthetic induction (P < 0.05). CONCLUSIONS: Ten minutes of pre-warming has the same effectiveness as 30 minutes of pre-warming for preventing inadvertent perioperative hypothermia. It is a preferable choice for the patients scheduled for surgery less than 120 minutes under general anesthesia.

Comparison of amino acid infusion with a forced-air warming system for rewarming hypothermic postoperative cancer patients without shivering / 中国癌症杂志

Background and purpose:Perioperative hypothermia will affect the prognosis of cancer patients. Amino acid infusion can increase the core temperature by endogenous thermogenesis. And the forced-air warming system has gained high acceptance as a measure for rewarming. This study aimed to find out whether amino acid infusion was effective to treat postoperative hypothermia and how well the treatment effect was when compared with the forced-air warming system.Methods:Fifty-seven ASAⅠ orⅡ patients aged 18-60 years undergoing elective esophageal or gastric cancer operation under epidural-general anesthesia and whose core temperature were below 36℃. When admitted to the recovery room wererandomly divided into 3 groups (n=19): GroupⅠ received intravenous infusion of mixed amino acid at a rate of 2 mL·kg-1·h-1 (A); GroupⅡ received a forced-air system (B); groupⅢreceived no therapy (C). Rectal temperature and thermal comfort were recorded per 5 min during the ifrst 1 h and oral temperature and thermal comfort were recorded at the 2, 6 and 24 h. ABG was recorded when patients were admitted to the recovery room and at the ifrst hour.Results:At the ifrst hour, the rectal temperature and thermal comfort of groups A and B were higher when compared with group C (P0.05). At the second and sixthhour, the temperature and thermal comfort of group A were higher when compared with group B and C (P0.05). At the 24th hour, there were no statistically signiifcant differences in the temperature and thermal comfort among the three groups (P>0.05). Conclusion:The rewarming effect of infusion of mixed amino acid is better than that of the forced-air warming system. It is the more effective and convenient method to rewarm the postoperative hypothermia.

Clinical considerations in the use of forced-air warming blankets during orthognathic surgery to avoid postanesthetic shivering

BACKGROUND: During head and neck surgery including orthognathic surgery, mild intraoperative hypothermia occurs frequently. Hypothermia is associated with postanesthetic shivering, which may increase the risk of other postoperative complications. To improve intraoperative thermoregulation, devices such as forced-air warming blankets can be applied. This study aimed to evaluate the effect of supplemental forced-air warming blankets in preventing postanesthetic shivering. METHODS: This retrospective study included 113 patients who underwent orthognathic surgery between March and September 2015. According to the active warming method utilized during surgery, patients were divided into two groups: Group W (n = 55), circulating-water mattress; and Group F (n = 58), circulating-water mattress and forced-air warming blanket. Surgical notes and anesthesia and recovery room records were evaluated. RESULTS: Initial axillary temperatures did not significantly differ between groups (Group W = 35.9 ± 0.7℃, Group F = 35.8 ± 0.6℃). However, at the end of surgery, the temperatures in Group W were significantly lower than those in Group F (35.2 ± 0.5℃ and 36.2 ± 0.5℃, respectively, P = 0.04). The average body temperatures in Groups W and F were, respectively, 35.9 ± 0.5℃ and 36.2 ± 0.5℃ (P = 0.0001). In Group W, 24 patients (43.6%) experienced postanesthetic shivering, while in Group F, only 12 (20.7%) patients required treatment for postanesthetic shivering (P = 0.009, odds ratio = 0.333, 95% confidence interval: 0.147-0.772). CONCLUSIONS: Additional use of forced-air warming blankets in orthognathic surgery was superior in maintaining normothermia and reduced the incidence of postanesthetic shivering.

Comparison of Forced Air Warming and Radiant Heating on Body Temperature and Shivering of Post-operative Patients / 성인간호학회지

PURPOSE: This study compared the effects of forced air warming and radiant heating on body temperature and shivering of patients with postoperative hypothermia. METHODS: The quasi-experimental study was conducted with two experimental groups who had surgery under general anesthesia; 20 patients of group 1 experimented with the Bair Hugger as a forced air warming and 20 patients of group 2 experimented with the Radiant heater. The study was performed from July 3 to August 31, 2006 in a recovery room of an university hospital in a city. The effects of the experiment were measured by postoperative body temperature and chilling score at arrival and after every 10 minutes. The data were analyzed by t-test or chi-square-test, repeated measures ANCOVA using SPSS/WIN 12.0. RESULTS: The mean body temperature showed differences between the Bair Hugger group and Radiant Heater group at 40 minutes(F=-2.579, p=.034), 50minutes(F=-2.752, p=.027), and 60 minutes(F=-2.470, p=.047) after arrival to the recovery room. So, hypothesis 1 was partially accepted. The mean score of shivering showed differences between the Bair Hugger group and the Radiant Heater group, but it had no significant meaning. Hypothesis 2 was not accepted. CONCLUSION: We need more study to explore the effects and side effects of heating modalities to select a more effective heat treatment. The efficiency of heat modalities with regards to cost benefit, time consumption, and patients' discomfort such as burns should be considered.

Active Warming during Preanesthetic Period Reduces Hypothermia without Delay of Anesthesia in Cardiac Surgery / 대한마취과학회지

BACKGROUND: Intra-operative hypothermia adversely affects hemodynamics and post-operative recovery in cardiac surgery patients. This study evaluated the efficacy of active warming during the preanesthetic period on the prevention of intraoperative hypothermia in cardiac surgery patients. METHODS: After gaining the approval of Institutional Review Board and informed consent from the patients, sixty patients undergoing cardiac surgery were divided into control and prewarming group. The control group (n = 30) were managed with warm mattresses and cotton blankets, whereas the prewarming group (n = 30) were actively warmed with a forced-air warming device before anesthesia. Hemodynamic variables and temperature were recorded before anesthesia (Tpre) and at 30 min intervals after anesthesia (T30, T60, and T90). RESULTS: Before anesthesia, skin temperature was significantly higher in the prewarming group than in the control group. At T90, core temperature was significantly higher in the prewarming group than in the control group. Intraoperative hypothermia (core temperature < 35.5oC) developed by T90 in 78% of patients in the control group and 44% of patients in the prewarming group. Moreover, temperatures below 35oC developed in 58% of the conrol group and 17% of the prearming group. CONCLUSIONS: Active warming just before anesthesia reduced the incidence and degree of hypothermia in patients undergoing cardiac surgery, with no delay of anesthesia.