[Ultrasound-guided caudal block with ropivacaine in infraumbilical surgeries in pediatric patients].

Background: The use of local anesthetics as part of multimodal analgesia is an attractive concept in pediatric patients, since the evaluation and management of pain is a challenge in children under 7 years of age. Despite having guidelines and multiple studies on volume calculation, no safe and effective recommendation has been issued. Objective: To demonstrate that ultrasound-guided caudal block with a dose of 0.75 mL/kg of 0.2% ropivacaine has the same analgesic effect as a dose of 1.2 mL/kg. Material and methods: Randomized, prospective, longitudinal, comparative equivalence clinical trial. One hundred patients 0-7 years of age scheduled for elective or emergency infraumbilical surgery were enrolled between April 2021 and January 2022. Children were randomized 1:1 to be assigned to ultrasound-guided caudal block. Results: 100 patients divided into two groups with 0.2% ropivacaine volumes (0.75 mL vs. 1.2 mL). Both groups demonstrated the trans-anesthetic and post-anesthetic sedoanalgesia variables without significant differences for both groups on the FLACC pain scale after surgery and in recovery (p > 0.5), in the pain reassessment on the FLACC scale in the office called chronic pain (p > 0.5) in both groups. No complications were reported in the follow-up consultations and no arrhythmias were reported in both groups during surgery. Conclusions: the results of both groups did not show differences between a volume of 0.75 mL and 1.2 mL, the administration of 0.2% ropivacaine is favored with the use of ultrasound, which allows effective administration of lower doses of local anesthetic with reduced risk of complications. It is necessary to carry out studies in other types of surgery to compare the use of less volume of local anesthetic compared to the Melman formula used in this study.