Comparison of Active and Passive Perioperative Warming Techniques in Reducing Intraoperative Blood Loss

Each Investigator reviews the most current Instructions for Use for Bair Hugger Forced air Warming System to assess the contraindications, warnings, and precaution sections with respect to risks and benefits for treating potential patients. 60 patients will be enrolled preliminary in this clinical trial. Equal size of 30 patients were allocated randomly into interventional or control group. Randomization will be performed after the patient has met all eligibility criteria, including the general inclusion or exclusion and the patient or legally authorized representative has signed an informed consent form prior to any study related procedure. Prior to induction, patients in the interventional group were provided 15 to 30 minutes forced air warming using the Bair Hugger warming unit, either in the pre-anesthesia area or OR,which may add to the total heat content of the body helping to reduce the effects of redistribution temperature drop for procedures using a temperature management strategy. The Bair Hugger warming unit is placed on its highest temperature setting and will be adjusted by the investigator depending on temperature monitoring. Temperature will be measured in both groups by either Spot-On sensor and tympanic membrane thermometer. Statistical analysis will be performed after the data of 30 cases (both groups) were available and the sample size will be re-estimated based on preliminary data analysis. Continuous variables will be summarized with mean, median, standard deviation, minimum and maximum, as applicable. Categorical variables will be summarized with frequency and percentage. Student t test will be used to compare means for continuous variables. A Chi square test or a Fisher's exact test will be used to compare proportions for categorical variables. Multiple regression will be performed to assess the risk ratios of patients developing hypothermia and will be expressed as an risk ratio along with a 95% confidence interval.