Effect of propofol on the auditory evoked response and oesophageal contractility

Six patients were anaesthetized with 70% nitrous oxide in oxygen supplemented by infusion of propofol 40, 80, 120, 160 and 200 micrograms kg-1 min-1 sequentially in successive 10-min periods. Auditory evoked response (AER) and lower oesophageal contractility (LOC) were monitored. The AER findings were consistent with those noted in previous studies of i.v. agents. Early cortical waves showed attenuation of Pa and Nb amplitude (P less than 0.01) and increase in Pa and Nb latency (P less than 0.01; P less than 0.05) with increasing blood concentrations of propofol. Brainstem waves were not affected significantly. LOC, provoked and spontaneous, showed no consistent relationship with blood concentration of propofol. The two variables AER and LOC were not related.