Preadministration of low-dose ketamine reduces tourniquet pain in healthy volunteers

Abstract

We evaluated whether preadministration of low-dose ketamine could attenuate tourniquet pain and arterial pressure increase using high tourniquet pressure in ten healthy awake volunteers. Ketamine, 0.1 mg·kg⁻¹, or normal saline was given intravenously in a double-blind fashion before tourniquet inflation with a pressure of 400 mmHg at the thigh. Visual analog scale (VAS) scores and systolic blood pressure (SBP) were measured at 5-min intervals. Ketamine significantly reduced VAS scores compared to saline just after tourniquet inflation [90 (64–100) mm, median (range), with saline versus 66 (50–81) mm with ketamine, P < 0.01] and at 30 min [92 (61–100) mm with saline versus 70 (50–100) mm with ketamine, P < 0.03), and significantly prolonged tourniquet time (28 ± 6 min with saline, mean ± SD, versus 37 ± 7 min with ketamine, P < 0.01). SBP (120 ± 9 mmHg) significantly increased before tourniquet deflation (133 ± 16 mmHg) in the saline trial, but not in the ketamine trial. The results show that preadministration of low-dose ketamine attenuates tourniquet pain and arterial pressure increase during high-pressure tourniquet application and prolongs tourniquet time in healthy volunteers.