Canadian Journal of Anesthesia, Vol 10, 343-351, Copyright © 1963 by Canadian Anesthesiologists' Society

The Effect of Atropine and Neostigmine on Cardiac Rate and Rhythm during Methoxyflurane and Halothane Anaesthesia

¹ Department of Anaesthesia, University of Alberta Hospital, Edmonton, Alberta

The effects on cardiac rhythm of atropine 0.0040–0.01 mg./lb. body weight followed in four minutes by neostigmine 0.01 mg./lb. body weight have been studied in patients anaesthetized with halothane and methoxyflurane.

The incidence of arrhythmias was small and there were no ventricular abnormalities. This is attributed in part to the ventilation of the subjects, which was based on a minute volume 25–50 per cent in excess of the Radford nomogram.

Any slowing of the pulse below 60 per minute was treated at once with intravenous atropine. This complication was more common during halothane than methoxyflurane anaesthesia.

Gallamine in usual clinical dosage was found to exert no protective effect against neostigmine-induced bradycardia.

Attention was drawn to the relationship between the pulse rate prior to the administration of atropine and the rate eventually reached after the neostigmine, and the factors to be taken into consideration when atropine and neostigmine are to be used. The slower the pulse before the atropine, the slower it becomes after neostigmine.

The opinion is expressed that it is preferable to use neostigmine in the presence of methoxyflurane anaesthesia rather than halothane.