Comparison of a New Patient Warming System Using Polymer Conductive Warming With Forced Air Warming During Surgery (HDV)

Two patient warming systems will be compared with 40 patients each in a convective warming group (BairHugger, Arizant) and in a conductive warming group (HotDog, Augustine Biomedical).

The patients will undergo small to medium trauma surgery and will be warmed with the randomized device - the hypothesis is, that the area under the standardized core temperature / time curve is significantly greater in the conductive warming group. Secondary outcome is the mean skin temperature / time area under the curve.

Study Overview

• Status: Completed
• Conditions: Hypothermia
• Intervention / Treatment: Device: Patient Warming with conductive / convective warming

Detailed Description

General study design We will study 200 patients (18-90 years) undergoing elective orthopedic surgery at the trauma surgery unit. The patients must have normal weight (20-30 BMI), the duration of surgery should last between 3 - 4 hours. There will be no other exclusion criteria (except severe peripheral arterial disease in the warmed extremity), as forced air patient warming is routinely used for all patients during this procedure.

The patients will be randomly assigned via a computer generated randomization list to treatment with either polymer or forced air warming. Anaesthesia and fluid management will be administered as desired by the anaesthesiologist.

Before warming four skin temperature probes will be attached to the upper arm, chest, abdomen and back of the patients to calculate mean body temperature. A probe (Mallinckrodt Anesthesiology Products, Inc., St. Louis, MO) will be introduced in the ear to measure core temperature. Afterwards, treatment with BairHugger or HotDog will be started.

The measurements will be recorded every five minutes until the end of surgery when intraoperative warming is stopped.

Differences between core temperatures will be analyzed both by using the summary measure of AUC (area under the curve) and by comparing the core-temperature at the end of surgery in the polymer and the forced air group with two-tailed, unpaired t tests if normally distributed and with a Wilcoxon test, if not normally distributed (distribution tested by K-S-test).

Results are expressed as means ± standard deviations if normally distributed, as median (IQ-Range) when not normally distributed.

Differences will be considered statistically significant when P < 0.05. We consider a difference in core temperature at the end of surgery of 0.5°C as clinically important. Considering this difference as well as a known standard deviation of approximately 1.5°C we will have to study 40 patients in each arm of the study to achieve statistical significance using a power of 90% and a p-value of 0.05.

• Study Type: Interventional
• Enrollment (Actual): 80
• Phase: Phase 3

Contacts and Locations

Study Locations

• Austria
  • Vienna, Austria, 1090
    • Medical University of Vienna

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• The patients must have normal weight (20-30 BMI), the duration of surgery should last between 3 - 4 hours.
• There will be no other exclusion criteria , as forced air patient warming is routinely used for all patients during this procedure.

Exclusion Criteria:

• Severe peripheral artery disease in the warmed extremity

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Forced Air; Warming with forced air (BairHugger)	Device: Patient Warming with conductive / convective warming; Warming device set to maximum (43 °C)
Experimental: Conductive Warming; Warming with the conductive device (HotDog)	Device: Patient Warming with conductive / convective warming; Warming device set to maximum (43 °C)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Area under the standardized "core temperature * time" curve	intraoperatively

Secondary Outcome Measures

Outcome Measure	Time Frame
Area under "mean skin temperature * time" curve	intraoperatively

Collaborators and Investigators

• Sponsor: Medical University of Vienna
• Investigators: Principal Investigator: Oliver Kimberger, M.D., Medical University of Vienna

Publications and helpful links

General Publications

• Brandt S, Oguz R, Huttner H, Waglechner G, Chiari A, Greif R, Kurz A, Kimberger O. Resistive-polymer versus forced-air warming: comparable efficacy in orthopedic patients. Anesth Analg. 2010 Mar 1;110(3):834-8. doi: 10.1213/ANE.0b013e3181cb3f5f. Epub 2009 Dec 30.

Study record dates

Study Major Dates

• Study Start: October 1, 2008
• Primary Completion (Actual): June 1, 2009
• Study Completion (Actual): June 1, 2009

Study Registration Dates

• First Submitted: October 14, 2008
• First Submitted That Met QC Criteria: October 14, 2008
• First Posted (Estimate): October 15, 2008

Study Record Updates

• Last Update Posted (Estimate): September 21, 2009
• Last Update Submitted That Met QC Criteria: September 18, 2009
• Last Verified: September 1, 2009

More Information

Terms related to this study

• Keywords: convective warming; intraoperative hypothermia; accidental hypothermia; patient warming; conductive warming; intraoperative normothermia
• Additional Relevant MeSH Terms: Body Temperature Changes; Hypothermia
• Other Study ID Numbers: HotDogVienna