Changes in body temperature following deflation of limb pneumatic tourniquet

Study Objectives: To investigate changes in both core and peripheral skin-surface temperatures during and after application of a unilateral leg pneumatic tourniquet in adult patients Design: Prospective, observational clinical study. Setting: University hospital. Patients: 21 ASA physical status I and II adult patients scheduled for elective leg orthopedic surgery with lumbar epidural anesthesia. Interventions: Rectal and fingertip skirt-surface temperatures were recorded every minute after steadystate lumbar epidural anesthesia was established. Measurements and Main Results: Significant (p < 0.05) increases in both rectal and fingertip temperatures were observed during tourniquet application for 91 +/- 6 minutes from 36.5 +/- 0.14 degrees C to 37.0 +/- 0.17 degrees C and from 32.6 +/- 0.79 degrees C to 35.5 +/- 0.44 degrees C, respectively. In contrast, both rectal and fingertip temperatures progressively decreased following tourniquet release-significant (p < 0.05) decreases in the rectal and fingertip temperatures were observed 6 and 5 minutes after tourniquet release, respectively. Decreases (approximate to maximum) in the rectal and fingertip temperatures lj minutes after tourniquet release were 0.25 +/- 0.05 degrees C and 1.26 +/- 0.26 degrees C, respectively. In each case, changes in fingertip temperature were approximately sis times greater than those in the rectal temperature. Conclusions: Limb tourniquets appear to cause thermal perturbations during epidural anesthesia. The progressive increases in core temperature during tourniquet application presumably resulted from constraint of metabolic hear to the core thermal compartment, and the greater increases in the shin-surface temperature during tourniquet application appear to represent vasodilation in response to the core hyperthermia. On the other hand redistribution of body heat and the efflux of hypothermic venous blood from the tourniqueted area into systemic circulation following tourniquet deflation probably decreased the core temperature, which might switch off the thermoregulatory vasodilation, leading to the decreases in shin-surface temperature. Recognition of these thermal perturbations are useful in diagnosing intraoperative thermal perturbations. (C) 1998 by Elsevier Science Inc.