The Effect of Convective Pre-warming on Intra-operative Thermoregulatory Capabilities

September 29, 2023 updated by: Boris Mraovic, University of Missouri-Columbia

A Prospective Randomized Clinical Trial Evaluating the Effect of Convective Pre-warming on Intra-operative Thermoregulatory Capabilities in Patients Enrolled in the TIGER Anesthesia Perioperative Protocol

This prospective randomized clinical trial will assess the effect of pre-operative convective warming on intra-operative thermoregulation in patients undergoing gastrointestinal or genitourinary surgical procedures with the Tiger anesthesia perioperative protocol.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Detailed Description

By the year 2030 the geriatric presence in the United States, defined as any adult >65 years of age, is estimated to reach around 20% of the entire population. Thus, understanding medical concepts as they relate to the elderly is becoming increasingly important. One such concept is that of hypothermia - a core body temperature < 36°C - for which age >65 has been found to be an independent risk factor. This complication is especially prevalent intra-operatively due to use of general anesthetics, cool ambient operating room (OR) temperatures, and impaired thermal regulation in the elderly.

The human body employs numerous mechanisms to maintain thermal homeostasis including: behavioral means of thermoregulation, sweating, pre-capillary vasodilation, non-shivering and shivering means of heat production, and arteriovenous shunt vasoconstriction. The first, and arguably most important, regulatory response to occur is that of vasoconstriction, which normally results in redistribution of blood from the relatively cool periphery to the warmer core compartment in order to confine metabolic heat to the central tissues. Patients undergoing general anesthesia experience reduced vasoconstriction due to decreased cold response thresholds while patients undergoing epidural anesthesia experience sympathetic blocks resulting in blunted vasoconstrictive responses. All patients experience the afore mentioned side effects of anesthetics, however it has been proven that the elderly are more susceptible to hypothermia due to lower vasoconstriction thresholds - determined by a temperature gradient of 4°C between the periphery and core.

First explored by Kurz et al. in 1993, it was found that use of nitrous oxide and isoflurane anesthesia lead to an approximately 1.2°C lower vasoconstriction threshold of 33.9±0.6 in the elderly versus 35.1±0.3 in the young (p < .01). This subject was again looked at in a 1997 study wherein the vasoconstriction threshold during nitrous oxide and sevoflurane was observed to be decreased by approximately 0.8°C in the elderly at 35.0±0.8 versus 35.8±0.3 in the young (p < .01). This is relevant because intraoperative hypothermia has long been known to lead to adverse outcomes such as increased incidence of myocardial ischemia, arrhythmias, coagulopathic states, and wound infections. In a 2014 retrospective cohort study by Billeter et al. patient's experiencing core temperatures <35°C had a four times increase in mortality with complication rates increasing two fold and incidence of stroke increasing six fold. To counter this thermoregulatory failure in patients, numerous methods of warming have been practiced over time to augment the normal body response.

One method used to decrease intraoperative hypothermia is warming patients before surgery via skin surface warmers. Numerous studies have found that even brief periods of pre-warming can improve intraoperative temperatures significantly for as long as 75-90 minutes after induction. In procedures lasting less than 90 minutes, Horn et al. found that as little as 10 minutes of pre-warming decreased incidence of intraoperative hypothermia from 69% to just 13% while Torossian et al. decreased the incidence from 60% to 38% in his study using a self-warming blanket for 30 minutes pre-operatively. Studies have also shown that longer pre-warming, of 45-60 minutes, can prevent hypothermia for up to 2 hours after induction.

While significant research has been performed on the effects of warming patients before they undergo surgical procedures, scant evidence demonstrates the effect of pre-warming in the elderly. In one article specifically looking at pre-warming in the elderly (mean age ~72-73) it was found that, after pre-warming for 20 minutes, there was no significant change in incidence of hypothermia but there was a significant difference in severity of hypothermia when it did occur. This study focused only on men undergoing transurethral resection of the prostate however, and suffers from lack of generalizability. With the proportion of the geriatric population continuing to expand, and the potential adverse effects resulting from their increased susceptibility to intraoperative hypothermia, it is of the utmost importance to look into methods to counter this dilemma and expand the database on the topic.

Study Type

Interventional

Enrollment (Actual)

10

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Missouri
      • Columbia, Missouri, United States, 65212
        • University Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • ASA I-IV
  • Other inclusion criteria as delineated in the TIGER anesthesia perioperative protocol

Exclusion Criteria:

  • Inability to obtain written informed consent
  • Inability to obtain core body temperature recordings
  • Family history of malignant hyperthermia
  • Preoperative temperature > 38° C
  • Other exclusion criteria as delineated in the TIGER anesthesia perioperative protocol

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Convective pre-warming
Undergo convective warming during the preoperative preparations, completed for a minimum of 60 minutes prior to entering the operating room
Device: Bair Hugger™ Temperature Management Unit Model 750
Forced-air temperature management unit used for preoperative and intraoperative participant warming
Device: 3M™ Bair Paws™ Flex Gown
Bair Paws™ patient warming gown used for preoperative and intraoperative participant warming
No Intervention: Standard of care
Undergo standard of care, which includes providing each patient with blankets and sheets, as well as more blankets on patient request.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Core Body Temperature
Time Frame: Day 1
Change in core temperature between induction of anesthesia and end of skin preparation
Day 1

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Skin Temperature
Time Frame: Day 1
Change in skin temperature between arrival to the holding area and departure to the operating room, and arrival to the PACU
Day 1
Intraoperative Temperatures
Time Frame: Day 1
Core body temperature measured intraoperatively
Day 1
Temperature Differences Between Different Age Groups
Time Frame: Day 1
Differences in temperature changes between elderly (≥ 65 years) and younger patients (< 65 years).
Day 1

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Missouri-Columbia

Investigators

  • Principal Investigator: Boris Mraovic, MD, University of Missouri-Columbia

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 26, 2017

Primary Completion (Actual)

November 7, 2018

Study Completion (Actual)

November 7, 2018

Study Registration Dates

First Submitted

March 13, 2019

First Submitted That Met QC Criteria

March 13, 2019

First Posted (Actual)

March 15, 2019

Study Record Updates

Last Update Posted (Actual)

October 2, 2023

Last Update Submitted That Met QC Criteria

September 29, 2023

Last Verified

September 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2008755

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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