Ultrasound assessment of cranial spread during caudal blockade in children: Effect of different volumes of local anesthetic

BACKGROUND: Ultrasound-guided caudal block injection is a simple, safe, and effective method of anesthesia/analgesia in pediatric patients. The volume of caudal drug required has always been a matter of debate. MATERIALS AND METHODS: This present prospective, randomized, double-blinded study aimed to measure extent of the cranial spread of caudally administered levobupivacaine in Indian children by means of real-time ultrasonography. Ninety American Society of Anesthesiologists I/II children scheduled for urogenital surgeries were enrolled in this trial. Anesthesia and caudal analgesia were administered in a standardized manner in the patients. The patients received 0.5 ml/kg or 1 ml/kg or 1.25 ml/kg of 0.125% levobupivacaine according to the group allocated. Cranial spread of local anesthetic was noted using ultrasound. RESULTS: There was no difference in the spread when related to age, sex, weight, or body mass index. A significant difference of ultrasound-assessed cranial spread of the local anesthetic was found between Group 1 (0.5 ml/kg) with both Group 2 (1 ml/kg) (P = 0.001) and with Group 3 (1.125 ml/kg) (P < 0.001) but there is no significant difference between Group 2 and Group 3 (P = 0.451) revealing that spinal level spread is only different between 0.5 ml/kg and 1 ml/kg of local anesthetic. CONCLUSION: In conclusion, the ultrasound assessment of local anesthetic spread after a caudal block showed that cranial spread of the block is dependent on the volume injected into the caudal space. Since there was no difference between 1 ml/kg and 1.25 ml/kg, to achieve a dermatomal blockade up to thoracic level, we might have to increase the dose beyond 1.25 ml/kg, keeping the toxic dose in mind.