Clinical trial NCT03876808: The Effect of Convective Pre-warming on Intra-operative Thermoregulatory Capabilities
Official title: 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
Study type: INTERVENTIONAL
Overall status: TERMINATED
Phase: NA
Conditions: Temperature Change, Body
Keywords: temperature
prewarming
convective warming
thermoregulation
gastrointestinal surgery
genitourinary surgery
Lead sponsor: University of Missouri-Columbia
Sponsor class: OTHER
First posted: 2019-03-15
Enrollment: 10
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: 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.

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.

Eligibility criteria: 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

Primary outcomes:
measure: Core Body Temperature
timeFrame: Day 1
Secondary outcomes:
measure: Skin Temperature
timeFrame: Day 1
measure: Intraoperative Temperatures
timeFrame: Day 1
measure: Temperature Differences Between Different Age Groups
timeFrame: Day 1
Other outcomes:
Locations:
city: Columbia
country: United States
facility: University Hospital
state: Missouri
Study officials:
affiliation: University of Missouri-Columbia
name: Boris Mraovic, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Centers for Disease Control and Prevention. The state of aging and health in America 2013. Atlanta, GA: Centers for Disease Control and Prevention, US Department of Health and Human Services, 2013.
citation: Billeter AT, Hohmann SF, Druen D, Cannon R, Polk HC Jr. Unintentional perioperative hypothermia is associated with severe complications and high mortality in elective operations. Surgery. 2014 Nov;156(5):1245-52. doi: 10.1016/j.surg.2014.04.024. Epub 2014 Jun 16.
citation: Frank SM, Beattie C, Christopherson R, Norris EJ, Rock P, Parker S, Kimball AW Jr. Epidural versus general anesthesia, ambient operating room temperature, and patient age as predictors of inadvertent hypothermia. Anesthesiology. 1992 Aug;77(2):252-7. doi: 10.1097/00000542-199208000-00005.
citation: Sessler, Daniel I. Chapter 8: preoperative thermoregulation. Geriatric Anesthesia, 2nd ed., Springer, New York, NY: 107-118, 2008.
citation: Glosten B, Hynson J, Sessler DI, McGuire J. Preanesthetic skin-surface warming reduces redistribution hypothermia caused by epidural block. Anesth Analg. 1993 Sep;77(3):488-93. doi: 10.1213/00000539-199309000-00012.
citation: Kurz A, Plattner O, Sessler DI, Huemer G, Redl G, Lackner F. The threshold for thermoregulatory vasoconstriction during nitrous oxide/isoflurane anesthesia is lower in elderly than in young patients. Anesthesiology. 1993 Sep;79(3):465-9. doi: 10.1097/00000542-199309000-00008.
citation: Ozaki M, Sessler DI, Matsukawa T, Ozaki K, Atarashi K, Negishi C, Suzuki H. The threshold for thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is reduced in the elderly. Anesth Analg. 1997 May;84(5):1029-33. doi: 10.1097/00000539-199705000-00014.
citation: Kim JY, Shinn H, Oh YJ, Hong YW, Kwak HJ, Kwak YL. The effect of skin surface warming during anesthesia preparation on preventing redistribution hypothermia in the early operative period of off-pump coronary artery bypass surgery. Eur J Cardiothorac Surg. 2006 Mar;29(3):343-7. doi: 10.1016/j.ejcts.2005.12.020. Epub 2006 Jan 24.
citation: Perl T, Peichl LH, Reyntjens K, Deblaere I, Zaballos JM, Brauer A. Efficacy of a novel prewarming system in the prevention of perioperative hypothermia. A prospective, randomized, multicenter study. Minerva Anestesiol. 2014 Apr;80(4):436-43. Epub 2013 Oct 3.
citation: Horn EP, Bein B, Bohm R, Steinfath M, Sahili N, Hocker J. The effect of short time periods of pre-operative warming in the prevention of peri-operative hypothermia. Anaesthesia. 2012 Jun;67(6):612-7. doi: 10.1111/j.1365-2044.2012.07073.x. Epub 2012 Feb 29.
citation: Torossian A, Van Gerven E, Geertsen K, Horn B, Van de Velde M, Raeder J. Active perioperative patient warming using a self-warming blanket (BARRIER EasyWarm) is superior to passive thermal insulation: a multinational, multicenter, randomized trial. J Clin Anesth. 2016 Nov;34:547-54. doi: 10.1016/j.jclinane.2016.06.030. Epub 2016 Jul 17.
citation: Vanni SM, Braz JR, Modolo NS, Amorim RB, Rodrigues GR Jr. Preoperative combined with intraoperative skin-surface warming avoids hypothermia caused by general anesthesia and surgery. J Clin Anesth. 2003 Mar;15(2):119-25. doi: 10.1016/s0952-8180(02)00512-3.
citation: Jo YY, Chang YJ, Kim YB, Lee S, Kwak HJ. Effect of Preoperative Forced-Air Warming on Hypothermia in Elderly Patients Undergoing Transurethral Resection of the Prostate. Urol J. 2015 Nov 14;12(5):2366-70.
citation: Sessler DI, Schroeder M, Merrifield B, Matsukawa T, Cheng C. Optimal duration and temperature of prewarming. Anesthesiology. 1995 Mar;82(3):674-81. doi: 10.1097/00000542-199503000-00009.