Elsevier

Journal of Clinical Anesthesia

Volume 4, Issue 3, May–June 1992, Pages 194-199
Journal of Clinical Anesthesia

Original contribution
Intraoperative warming therapies: a comparison of three devices

https://doi.org/10.1016/0952-8180(92)90064-8Get rights and content

Abstract

Study Objective: To compare the effectiveness of three commonly used intraoperative warming devices.

Design: A randomized, prospective clinical trial.

Setting: The surgical suite of a university medical center.

Patients: Twenty adult patients undergoing kidney transplantation for end-stage renal disease.

Interventions: Patients were assigned to one of four warming therapy groups: circulating-water blanket (40°C), heated humidifier (40°C), forced-air warmer (43°C, blanket covering legs), or control (no extra warming). Intravenous fluids were warmed (37°C), and, fresh gas foes was 5 Llmin for all groups. No passive heat and moisture exchangers were used.

Measurements and Main Results: The central temperature (tympanic membrane thermocouple) decreased approximately 1 °c during the first hour of anesthesia in all groups. After three hours r f anesthesia, the decrease in the tympanic membrane temperature from baseline (preinduction) was least in the forced-air warmergroup (−0.5°C ±0.4°C), intermediate in the circulating-water blanket group (−1.2°C ±0.4°C), and greatest in the heated humidifier and control groups (−2.0°C ± 0.5°C and −2.0°C ± 0.7°C, respectively). Total cutaneous heat loss measured with distributed thermal flux transducers was approximately 35W (walls = joules/sec) less in the forced-air warmer group than in the others. Heal gain across the back from the circulating-water blanket was approximately 7W versus a loss of approximately 3W in patients lying on a standard foam mattress.

Conclusion: The forced-air- warmer applied to only a limited skin surface area transferred more heat and was clinically more effective (at maintaining central body temperature) than were the other devices. The characteristic early decrease in central temperature observed in all groups regardless of warming therapy is consistent with the theory of anesthetic-induced heat redistribution within the body.

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    Presented in part at the Annual Meeting of the International Anesthesia Research Society, San Antonio, Texas, March 1991.

    This study was supported by Augustine Medical, Inc., Eden Prairie, MN, and National Institutes of Health grant #R29 GM39723. Dr. Sessler is a consultant for Augustine Medical, Inc.

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