Bair hugger forced-air warming maintains normothermia more effectively than thermo-lite insulation

doi:10.1016/0952-8180(94)90077-9

Journal of Clinical Anesthesia

Volume 6, Issue 4, July–August 1994, Pages 303-307

https://doi.org/10.1016/0952-8180(94)90077-9 Get rights and content

Abstract

Study Objective: To compare the ability of forced-air warming and reflective insulation to maintain intraoperative normothermia.

Design: Prospective, randomized clinical trial.

Setting: Operating rooms of a general hospital.

Patients: 20 ASA physical status I and II patients undergoing elective total hip arthroplasty.

Interventions: Patients were randomly assigned to be warmed intraoperatively using forced-air or reflective insulation. Inspired gases were conditioned using a heat-and-moisture exchanger in both groups, and infused intravenous fluids were warmed to 37°C.

Measurements and Main Results: Distal esophageal (core) temperatures decreased approximately 0.5°C in both groups during the first 45 minutes of anesthesia. Subsequently, core temperatures increased slightly in the patients given forced-air warming. In contrast, core temperatures continued to decrease in patients covered with reflective insulation. After 135 minutes of anesthesia, core temperatures were 36.4 ± 0.6°C (mean ± SD) in the forced-air group but only 35.4 ± 0.6°C in the insulated group (p < 0.01, unpaired t-test). These data indicate that forced-air warming is superior to reflective insulation.

Conclusion: Reflective insulation was unable to maintain intraoperative normothermia during total hip arthroplasty. Active warming, such as that provided by forced air, was required to prevent hypothermia.

References (36)

F. Carli et al.
Effect of peroperative normothermia on postoperative protein metabolism in elderly patients undergoing hip arthroplasty
Br J Anaesth
(1989)
J.M. Hynson et al.
Intraoperative warming therapies: a comparison of three devices
J Clin Anesth
(1992)
C.F. Roe
Effect of bowel exposure on body temperature during surgical operations
Am J Surg
(1971)
A.R. Forbes
Humidification and mucus flow in the intubated trachea
Br J Anaesth
(1973)
I.B. Mekjavic et al.
Core temperature “null zone.”
J Appl Physiol
(1991)
D.I. Sessler et al.
The thermoregulatory threshold in humans during halothane anesthesia
Anesthesiology
(1988)
D.I. Sessler et al.
The thermoregulatory threshold in humans daring nitrous oxide-fentanyl anesthesia
Anesthesiology
(1988)
R. Støen et al.
The thermoregulatory threshold is in-versely proportional to isoflurane concentration
Anesthesiology
(1990)
D.E. Washington et al.
Painful stimulation minimally increases the thermoregulatory threshold for vasoconstriction during enflurane anesthesia in humans
Anesthesiology
(1992)
J.M. Hynson et al.
Thermoregulatory vasoconstriction during propofol/nitrous oxide anesthesia in humans: threshold and oxyhemoglobin saturation
Anesth Analg
(1992)

T. Heier et al.

Mild intraoperative hypothermia increases duration of action and spontaneous recoverv of vecuronium blockade during nitrous oxide-isoflurane anesthesia in humans

Anesthesiology

(1991)

C.R. Valeri et al.

Hypothermia-induced reversible platelet dysfunction

Ann Surg

(1987)

Sheffield C.W. Sessler D.I. Hunt T.K. Scheuenstuhl H Mild hypothermia during halothane anesthesia decreases resistance...

Sheffield (:W. Sessler DI. Hunt T.K.: Mild hypothermia impairs resistance to E. Coli infections in guinea pigs. Acta...

D.I. Sessler et al.

Physiological responses to mild perianesthetic hypothermia in humans

Anesthesiology

(1991)

C.F. Roe et al.

The influence of body temperature on early postoperative oxygen consumption

Surgery

(1966)

J.A. Wagner et al.

Age and temperature regulation of humans in neutral and cold environments

J Appl Physiol

(1974)

F. Carli et al.

An investigation of factors affecting postoperative rewarming of adult patients

Anaesthesia

(1986)

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Active external rewarming involves the direct exposure of the patient’s skin to an exogenous heat source, which has the potential for thermal injury [1]. Forced-air rewarming blankets (Bair Hugger™) have been shown to be effective for the treatment of accidental hypothermia without causing thermal injury [20–22] and for maintenance of core temperature during surgery [23]. Whole-body immersion in hot water, which causes massive vasodilatation and hypotension, is contraindicated as a rewarming method in hypothermic patients [24].
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Prevention of Perioperative Hypothermia: A Prospective, Randomized, Controlled Trial of Bair Hugger Versus Inditherm in Patients Undergoing Elective Arthroscopic Shoulder Surgery
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The proximity of the shoulder to the thorax and great vessels, the inability to apply a tourniquet proximal to the shoulder, and the large volumes of fluid passing through the joint during shoulder arthroscopy increase the likelihood of this procedure adversely affecting the CBT. Numerous studies have established the benefits of forced-air warming in preventing intraoperative hypothermia during a variety of surgical procedures.17-23 The benefits of forced-air warming over the use of a single cotton blanket in preventing hypothermia in patients undergoing shoulder arthroscopy has already been described.24
To determine if a clinically significant difference in the core body temperature (CBT) exists between the Bair Hugger (BH) and Inditherm (IT) warming devices in patients undergoing arthroscopic shoulder surgery.
This was a parallel, 2-treatment, prospective, randomized, controlled trial conducted in patients undergoing elective arthroscopic shoulder surgery in the beach-chair position using room-temperature irrigation fluid. The BH was used as the indicative forced-air warming device, whereas the IT served as the indicative resistive heating system. By use of a minimal clinically significant difference of 0.6°C and standard deviation of 0.6°C, a power analysis showed that a sample size of 90 patients (45 per group) would be required. Patients fulfilling the inclusion criteria were recruited from the clinics of the senior authors. Anesthetic and surgical protocols were standardized. The intraoperative CBT was recorded every 5 minutes using a nasopharyngeal thermistor probe. Demographic data as well as the volume of irrigation fluid used were also noted.
A steady decline in the CBT was observed in both groups up to 30 minutes after induction of anesthesia. Beyond 30 minutes, the BH group showed a gradual increase in temperature whereas it continued to decline in the IT group. A statistically significant difference in the CBT was observed from 60 minutes onward (P = .025). This difference continued to increase up to 90 minutes (P < .001). At no time was a rise in the CBT observed in the IT group. At completion of the study and surgical procedure, 13 of 47 patients in the BH group and 32 of 44 patients in the IT group had hypothermia (P = .0002).
The CBT was statistically significantly better with the use of the BH compared with the IT mattress. However, the differences in the CBT did not reach the level of clinical significance of 0.6°C. Far fewer patients in the BH group had hypothermia at the end of surgery. Therefore, this study supports the use of the BH in elective arthroscopic shoulder surgery for the prevention of hypothermia.
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High Efficiency Particulate Air Filters Do Not Affect Acute Infection Rates During Primary Total Joint Arthroplasty Using Forced Air Warmers
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Studies have suggested that forced-air warmers (FAWs) increase contamination of the surgical site. In response, FAWs with high efficiency particulate air filters (FAW-HEPA) were introduced. This study compared infection rates following primary total joint arthroplasty (TJA) using FAW and FAW-HEPA.
Primary TJA patients at a single healthcare system were retrospectively reviewed. A total of 5405 THA (n = 2419) and TKA (n = 2986) consecutive cases in 2013 and 2015 were identified. Patients in 2013 (n = 2792) had procedures using FAW, while FAW-HEPA was used in 2015 (n = 2613). The primary outcome was overall infection rate within 90-days. Sub-categorization of infections as periprosthetic joint infection (PJI) or surgical site infection (SSI) was also conducted. PJI was defined as reoperation with arthrotomy or meeting Musculoskeletal Infection Society (MSIS) criteria. SSI was defined as wound complications requiring antibiotics or irrigation/debridement.
The FAW and FAW-HEPA groups had similar rates of overall infection (1.65% [n = 46] vs 1.61% [n = 42], P > .99), SSI (1.18% [n = 33] vs 0.84% [n = 22], P = .27), and PJI (0.47% [n = 13] vs 0.77% [n = 20], P = .22). Regression models did not show FAW to be an independent risk factor for increased overall infection (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.65-1.57, P = .97), SSI (OR 1.47, 95% CI 0.83-2.58, P = .18), or PJI (OR 0.53, 95% CI 0.25-1.13, P = .09).
FAW were not correlated with a higher risk of overall infection, SSI, or PJI during TJA when compared to FAW-HEPA devices.
Reflective Blankets Are as Effective as Forced Air Warmers in Maintaining Patient Normothermia During Hip and Knee Arthroplasty Surgery
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Laboratory simulation studies have also shown potential pathologic organisms in the hoses and filters of these forced air warming devices and have raised concerns about using them in an operating room where joint arthroplasties take place [13,15,19-21]. Previous studies have shown the effectiveness of passive warming devices to be inferior to active warming devices [2,3,16]. These studies have omitted an important part of maintaining normothermia, that is, prewarming of patients before the start of anesthesia.
The use of forced air warming devices in the operating room has been shown to cause disruption of laminar airflow and a potential for increase in surgical site contamination. In contrast, conductive warming devices such as reflective blankets do not disrupt airflow and therefore have no potential for this increase in surgical site infection. However, some studies have shown them to be inferior to forced air warming devices in maintaining normothermia. We tested the hypothesis that the use of reflective blankets is as effective as forced air warming devices in maintaining intraoperative normothermia after adequate prewarming.
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Our study shows that after a period of adequate prewarming, the use of reflective blankets is as effective as the use of forced air warming devices in maintaining normothermia in patients undergoing hip or knee arthroplasty.
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Research supports the practice of preprocedure warming as a method to prevent the development of unplanned perioperative hypothermia. ASPAN defines hypothermia as a core temperature lower than 36°C. The purpose of this quality improvement project was to explore the idea that preprocedure warming maintains perioperative normothermia. Information was obtained through retrospective chart reviews (n = 148). Temperatures were compared for patients who received standard preprocedure care versus patients who were warmed with a warming gown for one hour preprocedure. Before the institution of warming, about 50% of the patients received in the PACU were hypothermic. After the warming was instituted, only 12% of patients were received in a hypothermic state in the PACU. Concepts discussed in this paper include preprocedure warming, postprocedure hypothermia, and complications associated with hypothermia.

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^☆: Augustine Medical, Inc., Eden Prairie, MN, and Techstyles, Inc., Dallas, TX donated the warming covers used in this study.

^∗: Attending Anesthesiologist

^†: Chief Anesthesiologist.

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Original contributionBair hugger forced-air warming maintains normothermia more effectively than thermo-lite insulation☆

Abstract

Br J Anaesth

J Clin Anesth

Am J Surg

Br J Anaesth

Core temperature “null zone.”

J Appl Physiol

The thermoregulatory threshold in humans during halothane anesthesia

Anesthesiology

The thermoregulatory threshold in humans daring nitrous oxide-fentanyl anesthesia

Anesthesiology

The thermoregulatory threshold is in-versely proportional to isoflurane concentration

Anesthesiology

Painful stimulation minimally increases the thermoregulatory threshold for vasoconstriction during enflurane anesthesia in humans

Anesthesiology

Thermoregulatory vasoconstriction during propofol/nitrous oxide anesthesia in humans: threshold and oxyhemoglobin saturation

Anesth Analg

Mild intraoperative hypothermia increases duration of action and spontaneous recoverv of vecuronium blockade during nitrous oxide-isoflurane anesthesia in humans

Anesthesiology

Hypothermia-induced reversible platelet dysfunction

Ann Surg

Physiological responses to mild perianesthetic hypothermia in humans

Anesthesiology

The influence of body temperature on early postoperative oxygen consumption

Surgery

Age and temperature regulation of humans in neutral and cold environments

J Appl Physiol

An investigation of factors affecting postoperative rewarming of adult patients

Anaesthesia

Original contribution
Bair hugger forced-air warming maintains normothermia more effectively than thermo-lite insulation☆