The purpose of this study is to evaluate patients' temperatures after using one of two ventilator circuits (breathing systems): the ANAPOD™ Heat and Humidification System (ANAPOD™ system) or the standard ventilator circuit with a heat-moisture exchanger (standard ventilator). The ANAPOD™ system will provide additional heat and humidity to patients through their breathing tube while the standard ventilator will not. The investigators are doing this research study to find out if the ventilator circuit providing additional heat and humidity will keep patients warmer during surgery and after surgery.
Patients were randomly assigned to either the treatment group or the control group prior to surgery. Prior to induction, patients in the control group were given inspiratory gas at ambient air temperature (20-22 degrees Celsius) and patients in the treatment group were given inspiratory gas at warmed temperatures (40-41 degrees Celsius). All patients were induced with general anesthesia in the supine position and repositioned prone following endotracheal intubation and placement of an esophageal stethoscope with a temperature sensor, as per usual hospital practice. Esophageal temperatures were recorded within 30 minutes of the baseline esophageal temperature and every 10 minutes thereafter for the first hour post-induction. All patients had a blanket and forced air warming applied to their lower extremities and upper back at 43 degrees Celsius after draping. All patients had esophageal temperature measurements recorded every 30 minutes until the patient was repositioned supine. Core temperatures were recorded four hours post-induction for those patients reaching that timeframe.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
70
active heat and humidification during anesthesia by warming inspire gases without a heat-moisture exchanger
no active heat and humidification during anesthesia
Core Body Temperature
Core body temperature will be taken in the esophagus. The last recorded esophageal temperature will be used for surgeries not reaching 3 hours duration.
Time frame: Approximately four hours post-induction of general anesthesia (or last recorded temperature)
Intraoperative Core Temperatures Post-induction
Core body temperature will be taken in the esophagus after general anesthesia induction.
Time frame: Approximately 30 minutes, 60 minutes, 120 minutes post-induction of general anesthesia
Number of Subjects With Post-operative Shivering
Shivering in the post-anesthesia care unit will be assessed using the Bedside Shivering Assessment Scale. This is a 4 point scale and rate shivering as the following: absent, mild, moderate, or severe. Only the highest degree of patient shivering was used in the analysis.
Time frame: Approximately 2 hours after completion of the surgery
Hospital Length of Stay
Number of days in the hospital
Time frame: Surgery to hospital discharge
Overall Post-operative Temperature
Temperature at Post Anesthesia Care Unit (PACU) arrival.
Time frame: PACU arrival
Number of Participants With Transfusion Within 48 Hours of Surgery
Requirement of blood transfusion within 48 hours of surgery
Time frame: Within 48 hours of surgery
Estimated Blood Loss
The estimated blood loss per case was determined by the anesthesia provider by measuring the volume of blood in the suction canister while taking into account the amount of irrigation solution used.
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Time frame: duration of surgery