Propofol anaesthesia alters somatosensory evoked cortical potentials

This study evaluated the effects of propofol on somatosensory evoked cortical potentials in 20 ASA grade 1 or 2 patients who underwent spinal surgery. Anaesthesia consisted of propofol, dextromoramide, 50% nitrous oxide and oxygen mixture. The induction dose of propofol was 2 mg/kg and was followed by an infusion of 6 mg/kg for the first hour and 3 mg/kg subsequently. Somatosensory evoked cortical potentials were recorded on the scalp and compared to pre-operative values using Student's paired t-test. We observed a significant depression of evoked potential 10 minutes after induction, which continued until the early phase of recovery. Because of its short and quickly reversible action, propofol is an acceptable agent when clinical monitoring of the spinal cord is indicated but is not satisfactory when monitoring has to be based on somatosensory cortical evoked potentials.