Ultrasound-guided versus Conventional Caudal Blocks in Children: A Randomised Clinical Study

Introduction: Caudal epidural block is a popular regional anesthetic technique in children undergoing infraumbilical surgeries. Conventionally, a landmark-guided method is used to perform caudal epidural blocks. Although widely practiced, this method is associated with procedural difficulties such as multiple attempts, decreased success rates at the first puncture, as well as higher rates of complications including dural puncture, rectal injury, and intraosseous/intravenous (i.v.)/subcutaneous injections. In order to overcome the shortcomings of the conventional technique, various other methods have been described in clinical practice, including imaging-assisted techniques with fluoroscopy and Ultrasound (US). Aim: To compare the overall block success rates between the conventional and US-guided methods of caudal blocks in children. Materials and Methods: The present randomised clinical study was conducted in the Department of Anesthesiology, St. John's Medical College, Bengaluru, Karnataka, India, from November 2019 to September 2021. Sixty-four children, aged 1-8 years, belonging to the American Society of Anesthesiologists (ASA) physical status grade I and II, and undergoing elective inguinal hernial surgery were included in the study. After induction of general anesthesia, the children were administered caudal blocks based on the assigned groups: group A (conventional) - patients were given 0.5 mL/kg of 0.25% bupivacaine after the needle entered the sacral canal, and group B (USG) - patients were given 0.5 mL/kg of 0.25% bupivacaine immediately after the needle was visualised piercing the sacrococcygeal ligament in the longitudinal view. The parameters studied were overall block success rates, block performance times, and the number of attempts taken. Descriptive statistics were reported using mean +/- Standard Deviation ( SD) for continuous variables and number or percentage for categorical variables. Independent t-test and Mann-Whitney U test were used for normally distributed and non-normally distributed variables, respectively. Chi-square test was used to analyse differences between categorical variables. Results: A total of 64 children of both genders, aged 1-8 years, belonging to ASA physical status I and II, were included in the study. Overall block success rates were comparable between the two groups, with 28 (87.5%) in group A and 30 (93.8%) in group B. The mean block performance time was longer in group B (2.781 +/- 1.2439 minutes) compared to group A (1.578 +/- 0.5835 minutes) (p-value< 0.001). The number of attempts was lower in group B, with 100% success in the first attempt, as opposed to 68.8% in group A (p-value<0.05). Conclusion: Ultrasound-guided caudal block does not improve overall block success rates or block performance time, but it does improve success rates at the first attempt and thereby reduces the number of attempts.