Evaluating Adult Patient Temperatures During Lower Spinal Surgery

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

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.

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)