Effects of the addition of potassium to prilocaine or bupivacaine. Studies on brachial plexus blockade.

A double-blind comparison of prilocaine and prilocaine plus potassium chloride, and of bupivacaine with bupivacaine plus potassium chloride, in brachial plexus blockade (axillary approach) was obtained in two groups of 20 patients. The addition of potassium chloride made no difference to the characteristics of the block with prilocaine, but resulted in a more rapid onset of sensory loss when added to bupivacaine.