Comparison of the ocular effects of atropine or glycopyrrolate with two I.V. induction agents

Atropine and glycopyrrolate combined with either methohexitone or thiopentone were compared with the induction agent alone in patients undergoing electroconvulsive therapy. Patients acted as their own controls in each sub-group defined by induction agent. Pupil size, muscle twitches, presence of hiccups and the extent of oropharyngeal secretions were noted. Methohexitone produced a greater and more prolonged increase in pupil size than did thiopentone. The subsequent pupil size following the atropine-methohexitone mixture was significantly greater than that following the glycopyrrolate-methohexitone mixture. The combination of atropine with thiopentone produced a greater "secondary" mydriasis than thiopentone alone, or thiopentone combined with glycopyrrolate. The effect of the glycopyrrolate-thiopentone combination did not differ significantly from that of thiopentone alone. Methohexitone was associated with a greater incidence of hiccups, muscle twitching and excessive salivation.