ON THE DURATION OF SPINAL ANESTHESIA IN THE RABBIT

¹ From the Department of Pharmacology, The University of Minnesota Medical School, Minneapolis

1. The duration of sensory anesthesia produced by the intraspinal injections of a series of six local anesthetics in the rabbit has been determined.

2. The duration of this effect appeared to be closely related to the concentration of the local anesthetic in the injected fluid.

3. Motor paralysis began, as a rule, before sensory anesthesia was discernible and lasted until after the sensory effects had disappeared.

4. The average durations of sensory anesthesia produced by the minimal anesthetic doses or concentrations of the six local anesthetics have been found to be: procaine HCl, 0.9 per cent, 16 minutes; tutocaine, 0.5 per cent, 11 minutes; panthesine, 0.5 per cent, 18 minutes; metycaine, 0.86 per cent, 13 minutes; pantocaine, 0.05 per cent, 25 minutes; and nupercaine, 0.07 per cent, 41 minutes.