Tracheal versus intravenous atropine. A comparison of the effects on heart rate.

Atropine 600 micrograms was given either intravenously or intratracheally and the change in heart rate noted in a double-blind, randomised study of 40 anaesthetised patients. There was no significant difference between the two groups in the maximum increase in heart rate, 20.3 beats/minute in the tracheal compared to 21.4 beats/minute in the intravenous group. However, the maximum increase occurred significantly earlier in the tracheal group, 45.5 seconds after administration compared to 95.5 seconds in the intravenous group (p less than 0.01, 95% confidence interval 36.8-63.2 seconds). This study supports the clinical observation that tracheal and intravenous atropine are equally effective and suggests that the trachea should be the route of choice when a rapid response is required.