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

This is a randomized, open label, parallel two arm, clinical study, which compare the Bair Hugger forced-air warming blanket and the conventional warming care practice in China on patients undergoing major surgery to determine the impact of maintaining normothermia on intraoperative blood loss, requirement for transfusion of packed red blood cells and the changes of coagulation function.

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.

Eligibility Criteria:
Inclusion Criteria:

* Adult patients≥18 years old
* Preoperative core temperature between 36.0 and 37.5°C
* American Society of Anaesthesiologists（ASA） Physical Status Classification System I-III
* No transdermal meds on the target site
* Elective major surgeries included but not limited:

  * Hip replacement
  * Thoracic surgery (lobectomy and esophagectomy) or abdominal surgery

Exclusion Criteria:

* Less than 18 years old
* Uncontrolled insulin-dependent diabetes mellitus (preoperative glucose \>250 mg/dL)
* A preoperative temperature above 37.5°C or less than 36°C
* Hyperthyroidism and hypothyroidism
* Raynaud disease
* History of infection and fever within 4 weeks before surgery
* Use of steroid or immunosuppressant within 4 weeks before surgery
* History of bleeding disorders
* Clinically significant laboratory abnormalities
* Hgb ≤ 10.0 g/L
* Platelets ≤ 100,000 / mL
* WBC（white blood cell ） \<3000/dL
* Fibrinogen\<200 mg/dL
* Thromboplastin time\>40s
* Prothrombin time
* international normalized ratio(INR）\<70%