Objectives: Most anaesthetics depress cortical somatosensory evoked potentials (CSEPs). However, the modification of CSEPs during total intravenous anaesthesia using propofol remaining still unknown, justified this trial.
Type of study: Open, prospective, clinical study.
Methods: Nine consecutive patients requiring CSEPs monitoring for spine surgery, were studied. Anaesthesia was induced with propofol (2.5 mg.kg-1 then 10 mg.kg-1.h-1) and sufentanil (0.50 micrograms.kg-1 then 0.25 micrograms.kg-1.h-1). Maximum positive (P40) and negative (N50) waweform latencies, and the peak to peak amplitude of CSEPs (posterior tibial nerve stimulation, cortical recording), were recorded before induction, 30 min, 1 and 2 h after induction, and at the end of surgery. Data are means +/- SD.
Results: Duration of anaesthesia was 260 +/- 73 min. Propofol induced significant lengthening of CSEPS (P40: from 37 +/- 10 up to 41 +/- 11 ms; N50: from 45 +/- 11 up to 51 +/- 14 ms), and a significant decrease in amplitude (from 1.9 +/- 0.9 down to 0.8 +/- 0.4 microV), but these changes were stable from 30 min after the induction to the end of spine surgery. A motor response was obtained 29 +/- 14 min after the end of anaesthetic administration.
Conclusions: Total intravenous anaesthesia with propofol and sufentanil induces a small but stable lengthening of CSEPs latency and a stable decrease of its amplitude, which enable an appropriate monitoring of CSEPs during spine surgery.