Perioperative Accuracy of the Raiing Wireless Axillary Thermometer

Completed

Conditions: Major Surgery Under General Anesthesia

Interventions: Device: iThermonitor (WT701)

Registration Number: NCT02756910

Lead Sponsor: Peking Union Medical College Hospital

Brief Summary: A new wireless axillary thermometer from Raiing Medical uses a proprietary system, iThermonitor (WT701), to provide better estimates of core temperature than a conventional axillary probe. Improvement results in part because the axillary probe measures and records temperatures continuously every 4 seconds and includes software to compensate for ambient temperature and positional changes including arm abduction.

Whether the iThermonitor is sufficiently accurate for clinical use remains unknown. The investigators thus propose to evaluate the system in perioperative patients who often experience thermal perturbations over a range of several °C. Specifically, the investigators propose to determine the precision and accuracy of iThermonitor in surgical patients and during the initial hour of recovery. As in previous studies, the investigators will consider the thermometer sufficiently accurate for clinical use if most Raiing temperatures are within ±0.5°C of the reference temperature.

Detailed Description: Patient characteristics, including age, height, weight, sex, and ASA status, and details of the surgery, including procedure and postoperative diagnosis will be recorded. The investigator will record the time of anesthesia induction and emergence. At 10-minute intervals during surgery, the investigator will record inspired volatile anesthetic concentration, mean-arterial pressure, type of thermal management device(s), and urine output over the previous 10-minute interval.

After induction of general anesthesia (without restriction as to type), the anesthesiologist will insert a temperature sensor into the distal esophagus. The distance will be determined by maximal heart sounds (if a stethoscope is used), or the probe will be inserted 0.48.(sitting height) - 4.4 cm. If an esophageal probe cannot be used, a thermometer can be inserted to between 10 and 20 cm into the nasopharynx. The surgical team will position a Foley catheter with temperature sensor into the urinary bladder. Ambient temperature will be recorded from an electronic probe situated at the height of the patients, well away from any heat-producing equipment.

Axillary temperature will be recorded by iThermonitor, a Raiing Medical wireless module, paired to an iPhone. An adhesive patch provided by Raiing will be used to securely position the Railing probe in a shaved axilla before the anesthesia induction. Patients will be asked to adduct the ipsilateral arm for up to 5 minutes after the probe is inserted, or until the temperature displayed on the paired iPhone is stable. Thereafter, patients will be free to move their arms.Monitored arm position during surgery will be recorded (arm tightly tucked, arm loose at side, arm abducted).

Temperatures will be recorded at 10-minute intervals during surgery and during the initial postoperative hour. Just before anesthetic emergence, the esophageal or nasopharyngeal thermometer will be removed, but the Foley catheter retained. The axillary device will then be removed after an hour of recovery, and the study concluded. The Foley catheter can be removed or retained per clinical need.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 80

Inclusion Criteria

adults having an American Society of Anesthesiologists (ASA) physical status of 1-3
must be scheduled for surgery of the abdomen or pelvis that is expected to last 1.5-4 hours
require general endotracheal anesthesia and insertion of a Foley catheter

Exclusion Criteria

patients in whom neither esophageal nor nasopharyngeal temperature monitoring is practical
patients in whom active intravenous infusion is required in both arms
patients who are allergic to hydrogel

Study & Design

Study Type: OBSERVATIONAL

Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Surgery Patients >1.5 Hrs	iThermonitor (WT701)	Use esophageal catheter for core temperature monitoring, Foley catheter for bladder temperature monitoring, and iThermonitor (WT701) for axillary temperature monitoring

Primary Outcome Measures

Name	Time	Method
Accuracy of iThermonitor in Surgical Patients	From 1 to 3 hours after induction of anesthesia	Accuracy, defined as the true difference between reference and iThermonitor temperature. The esophageal temperature will be the core temperature reference during surgery. The primary outcome measure is the proportion of iThermonitor measurements for a patient that are within 0.5° C of the reference will be calculated, and this proportion (median, quartiles, 95% CI) will be summarized across patients. The Secondary outcome measure are bias and 95% CIs determined by repeated-measures Bland-Altman analysis. For each patient the average difference between the iThermometer and the reference temperature will be calculated. Patient iThermonitor measurements will be regressed on patient reference measurements to assess the Pearson correlation and 95% CI between iThermonitor and reference and to estimate the bias (slope) of device versus reference.

Secondary Outcome Measures