Evaluating Adult Patient Temperatures During Lower Spinal Surgery

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Comparing Patient Temperatures in Adults During Lower Spinal Surgery Using Either a Heated Ventilator Circuit or a Standard Ventilator Circuit With a Heat-Moisture Exchanger

Conditions
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Hypothermia

Intervention / Treatment
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* Device: Heated Ventilator Circuit
* Device: Standard Ventilator Circuit


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Elective spine surgery anticipated greater than three hours in duration Posterior approach An operative site between lumbar one and sacral one Involving two or more levels with fusion and/or instrumentation and/or revisions American Society of Anesthesiologists (ASA) Status of I-III Exclusion Criteria: Patients with a tracheostomy Preoperative temperature >38°C or <36°C on the day of surgery Active infection or erythema to the back White blood cell count greater than 10,500/microliter (mcL)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: randomized, trial (treatment or no treatment)
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Heated Ventilator Circuit<br>Heated and humidified inspired gases using the ANAPOD™ Heat and Humidification System (Westmed; Tucson, Arizona, USA) circuit prior to induction of general anesthesia in addition to standard ventilation and temperature management. | Device: Heated Ventilator Circuit<br>* active heat and humidification during anesthesia by warming inspire gases without a heat-moisture exchanger<br>* Other names: ANAPOD™ Heat and Humidification System;|
| Active Comparator: Standard Ventilator Circuit<br>Standard ventilation and temperature management. | Device: Standard Ventilator Circuit<br>* no active heat and humidification during anesthesia<br>* Other names: Thermovent 600; Portex;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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. | Approximately four hours post-induction of general anesthesia (or last recorded temperature) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intraoperative Core Temperatures Post-induction | Core body temperature will be taken in the esophagus after general anesthesia induction. | 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. | Approximately 2 hours after completion of the surgery | 
| Hospital Length of Stay | Number of days in the hospital | Surgery to hospital discharge | 
| Overall Post-operative Temperature | Temperature at Post Anesthesia Care Unit (PACU) arrival. | PACU arrival | 
| Number of Participants With Transfusion Within 48 Hours of Surgery | Requirement of blood transfusion within 48 hours of surgery | 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. | duration of surgery |