[Heart rate changes in propofol anesthesia--relation with excitatory movements]

Acceleration of heart rate simultaneously with excitatory movements was observed during anesthesia with propofol in four patients. Anesthesia was induced with propofol 2.5 mg.kg-1 i.v. and maintained with propofol 10 mg.kg-1.hr-1 i.v. About ten minutes after the induction, the patients showed jerking movements such as pronation or flexion of their arms, and/or plantar flexion. These movements lasted one or two seconds and appeared two or three times a minute. Three patients received vecuronium 0.1 mg.kg-1 and even after muscular relaxation acceleration of heart rate persisted. In one of two patients who had received midazolam 0.8 mg.kg-1, heart rate acceleration ceased. In one patient acceleration of heart rate and excitatory movements stopped after reducing the infusion rate of propofol from 10 mg.kg-1.hr-1 to 3 mg.kg-1.hr-1. Another patient with no involuntary movements showed no heart rate changes. These results suggest that heart rate acceleration in four patients was closely related to excitatory movements caused by propofol. As it was not influenced by muscular relaxation, heart rate monitoring would be useful to detect latent excitatory movements under muscular relaxation.