CHANGES IN BODY-TEMPERATURE FOLLOWING DEFLATION OF LIMB PNEUMATIC TOURNIQUET

Study Objectives: To investigate changes in both core and peripheral s kin-surface temperatures during and after application of a unilateral leg pneumatic tourniquet in adult patients Design: Prospective, observ ational clinical study. Setting: University hospital. Patients: 21 ASA physical status I and II adult patients scheduled for elective leg or thopedic surgery with lumbar epidural anesthesia. Interventions: Recta l and fingertip skirt-surface temperatures were recorded every minute after steadystate lumbar epidural anesthesia was established. Measurem ents and Main Results: Significant (p < 0.05) increases in both rectal and fingertip temperatures were observed during tourniquet applicatio n for 91 +/- 6 minutes from 36.5 +/- 0.14 degrees C to 37.0 +/- 0.17 d egrees C and from 32.6 +/- 0.79 degrees C to 35.5 +/- 0.44 degrees C, respectively. In contrast, both rectal and fingertip temperatures prog ressively decreased following tourniquet release-significant (p < 0.05 ) decreases in the rectal and fingertip temperatures were observed 6 a nd 5 minutes after tourniquet release, respectively. Decreases (approx imate to maximum) in the rectal and fingertip temperatures lj minutes after tourniquet release were 0.25 +/- 0.05 degrees C and 1.26 +/- 0.2 6 degrees C, respectively. In each case, changes in fingertip temperat ure were approximately sis times greater than those in the rectal temp erature. Conclusions: Limb tourniquets appear to cause thermal perturb ations during epidural anesthesia. The progressive increases in core t emperature during tourniquet application presumably resulted from cons traint of metabolic hear to the core thermal compartment, and the grea ter increases in the shin-surface temperature during tourniquet applic ation appear to represent vasodilation in response to the core hyperth ermia. On the other hand redistribution of body heat and the efflux of hypothermic venous blood from the tourniqueted area into systemic cir culation following tourniquet deflation probably decreased the core te mperature, which might switch off the thermoregulatory vasodilation, l eading to the decreases in shin-surface temperature. Recognition of th ese thermal perturbations are useful in diagnosing intraoperative ther mal perturbations. (C) 1998 by Elsevier Science Inc.