Osamu Nakanishi

Increase in the threshold of pain and touch sensation in the human face with clonidine plus 30% nitrous oxide

OBJECTIVEnThis study was undertaken to assess the effects of clonidine combined with 30% nitrous oxide on tactile and pain sensations in the human face.nnnSTUDY DESIGNnThirty-three subjects were involved in the study. The subjects were divided into 4 groups: 100% oxygen with placebo; 30% N2O with placebo; 100% oxygen with clonidine (0.075 mg), and 30% N2O with clonidine. Three tests for the threshold of pain sensation and tactile sensation were made at 60 minutes before and 0, 15, and 30 minutes during N2O or O2 inhalation.nnnRESULTSn(1) The N2O with clonidine significantly increased the threshold of pain and tactile sensation in comparison with the other 3 treatments. (2) In terms of pain sensation, both N2O and clonidine showed significant increases in threshold of pain in comparison with the control values.nnnCONCLUSIONSnThese results indicate that the analgesic effects of 30% nitrous oxide are enhanced when use of the gas is combined with prior clonidine administration.