Testing anal sphincter tone predicts the effectiveness of caudal analgesia in children.

UNLABELLED: In this study, we examined the effectiveness of caudal blocks and correlated it with the laxity of the patients' anal sphincter before emergence from anesthesia in 178 children undergoing inguinal and/or penile surgery. Bupivacaine 0.25% in a volume of 0.6-1.25 mL/kg was used in all patients. The presence of a lax anal sphincter at the end of surgery correlated significantly with the reduced administration of narcotics intraoperatively and in the postanesthesia care unit (P < 0.001). The sensitivity of the sphincter tone test was 98.1% with a 95% confidence interval (CI) ranging from 94.3% to 99.6%. The specificity of the test was 94.4% with a 95% CI of 72.0%-100%. The positive predictive value of this test in predicting adequate caudal block was excellent (99.4%) with a 95% CI of 96.1%-100%. The negative predictive value was better than average (85%) with a 95% CI of 62.9%-95.4%. We conclude that a lax anal sphincter can predict the effectiveness of analgesia after pediatric caudal blockade. A tight sphincter may suggest the need to repeat the block before the child awakens, or consider alternate methods of postoperative analgesia. IMPLICATIONS: A lax anal sphincter in children undergoing inguinal and/or penile surgery can predict the effectiveness of analgesia after pediatric caudal blockade.