[Changes in anal canal pressure during caudal and lumbar epidural anesthesia]

To compare anesthetic effect of caudal and lumbar epidural anesthesia, anal canal pressure during these anesthesia was measured. Anal canal pressure under resting condition decreased soon after injection of local anesthetics into epidural space in both groups. In early post injection stage the pressure decreased more in caudal group than in lumbar epidural group. The pressure when anus was contracted at will fall significantly further in caudal group than in lumbar group. These results suggest that caudal anesthesia should be utilized for obtaining full muscle relaxation of anal area in a short time compared with lumbar epidural anesthesia.