The effects of ultra-short acting barbiturate (thiopental sodium) on short latency potential of somatosensory evoked potential have been studied in twenty two patients without neurological disease.

The results were as follows:

1) The men values of P₄₀ potential latencies were 36.7±2.09 msec for the pre-anesthetic state, and 36.7±1.65 msec, 37.0±2.30 msec and 37.7±2.48 msec correspondingly for the post-anesthetic state after serial thiopental sodium infusion of 0.5mg/kg, 1.5mg/kg and 3.0mg/kg.

2) There was no statistical difference of P₄₀ potential latencies between pre-anesthetic and post-anesthetic states(P>0.05).