| Research Abstract |
The present experiment observed the somatic evoked potentials SEPs changes between different stimulus rates (1,0.5,0.5 T/sec), subjective painfulness evaluated by analogue pain scale and stimulus intensities, the effect of low doses diazepam injection (0.01, 0.02, 0.05mg/Kg, iv), diflunisal DFS 250mg p.o., and the changes in nitrous oxide anesthesia (room air, 100% 02,15% N20,30% N20,15% N20,100% 02), elicited by electric dental painful stimulation.
In SEPs between 50 msec to 500 msec following stimuli, five components were detected in all subjects(N70, P100, N155, P260,N350). Peak-to peak amplitudes increased as stimulus rate was decreased, especially N155-P260(P<0.01). No significantly changes in peak latencies were observed across different stimulus intencities. Peak-to-peak amplitude increased systematically with increased stimuli, especially N155-P260 and N70-P100(P<0.001). N65-P100 correlated with both subjective pain score and stimulus intencities. N155-P260 significantly correlated with subjective pain score.
The experiment group's peak latencies were slowed, especially P260(P<0.05), and N65-P100 amplitude was slightly increased after low doses diazepam injection.
One hour after taking diflunisal, amplitude of N155-P260 were decreased(p<0.005).
Upon comparison between nitrous oxide concentrations and the amplitude of SEPs, the most significant amplitude decrease was observed at N155-P260. As compared with the room air, graded reductions in the amplitude of SEPs were noted at pre-15% and 3/% nitrous oxid, particularly in the latter where the reduction was statistically significant (P<0.001). 30% nitrous oxide significantly delayed all elements of SEPs, while 15% nitrous caused significant increased in the early components of N70, P100 and N150, and tended to increase other components.
The results as described above suggested the possibility of SEPs as a useful index for determination of subjective painfulness.
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