Comparison of different quantitative sensory testing methods during remifentanil infusion in volunteers

Background. The aim of this study was to compare thermal andcurrent sensory testing stimuli with respect to opioid responsiveness. Methods. Eighteen healthy volunteers were randomized in a placebo-controlled,double-blind crossover study to receive an infusion of remifentanil0.08 µg kg^–1 min^–1 or saline for 40 min. Testprocedures included determination of pain perception thresholds(PPT) and pain tolerance thresholds (PTT) to heat, cold, andcurrent at 5, 250 and 2000 Hz, at baseline and at the end ofthe infusion. Results. Both current at 5 Hz (PPT 3.69 (SD 2.48) mA vs 2.01(1.52) mA; PTT 6.42 (2.79) mA vs 3.63 (2.31) mA; P<0.001)and 250 Hz (PPT 4.31 (2.42) mA vs 2.89 (1.57) mA; PTT 7.08 (2.68)mA vs 4.81 (2.42) mA; P<0.001) and heat (PPT 47.4 (2.7)°Cvs 45.2 (3)°C; PTT 51.1 (1.8)°C vs 49.7 (1.8)°C;P<0.05) detected a significant analgesic effect of remifentanilcompared with placebo. No analgesic effect was shown on coldor current at 2000 Hz. The magnitude of responsiveness of currentstimuli at 5 Hz and 250 Hz was superior to heat stimuli. Conclusion. Both current (5 and 250 Hz) and heat sensory testingdetected a significant analgesic effect of a remifentanil infusioncompared with saline. There was more response to current testing. Br J Anaesth 2003; 91: 203–8