The aim of this study was to compare thermal and current 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 remifentanil 0.08 μg kg−1 min−1 or saline for 40 min. Test procedures included determination of pain perception thresholds (PPT) and pain tolerance thresholds (PTT) to heat, cold, and current at 5, 250 and 2000 Hz, at baseline and at the end of the 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)°C vs 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 remifentanil compared with placebo. No analgesic effect was shown on cold or current at 2000 Hz. The magnitude of responsiveness of current stimuli at 5 Hz and 250 Hz was superior to heat stimuli.
Conclusion
Both current (5 and 250 Hz) and heat sensory testing detected a significant analgesic effect of a remifentanil infusion compared with saline. There was more response to current testing.
This study was presented in part at the Annual Meeting of the German Pain Society, Hamburg, Germany, September 2000 and at the Annual Meeting of the European Society of Anaesthesiologists, Vienna, April 2000.
