[Effect of dexmedetomidine on intraoperative somatosensory evoked potential monitoring]

Intraoperative somatosensory-evoked potential (SEP) monitoring has become a part of neurosurgical procedures. In this study, we evaluated the effect of dexmedetomidine on SEP monitoring during neurosurgical anesthesia.

Eight patients scheduled for neurosurgery were studied. Anesthesia was maintained with continuous infusion of propofol at 2 microg x ml(-1) concentration using target controlled infusion (TCI). A loading dose of dexmedetomidine was infused at 6 microg x kg(-1) hr(-1) for 10 min and SEP was recorded. Infusion of dexmedetomidine was continued at 0.5 microg x kg(-1) x min(-1) for 10 min and SEP was recorded. We measured the change of amplitude and latency of SEP (N20-P25) and compared to baseline values.

There was no statistically significant change in the cortical SEP amplitude (98.0 +/- 18.1% after a loading dose of dexmedetomidine and 112.7 +/- 16.8% at 0.5 microg x kg(-1) x min(-1) of dexmedetomidine, respectively) or latency (101.5 +/- 1.7% after a loading dose of dexmedetomidine and 101.9 +/- 1.7% at 0.5 microg x kg(-1) x min(-1) of dexmedetomidine, respectively). Mean blood pressure rose from 81 mmHg to 95 mmHg after initiation of dexmedetomidine infusion. Heart rate did not change.

These findings suggest that dexmedetomidine has possibilities to produce an ideal environment as an anesthetic adjunct in patients requiring intrapoerative SEP monitoring.