Ultrasound-guided caudal blockade and sedation for paediatric surgery: a retrospective cohort study

Data on safety and success rates of ultrasound-guided caudal blockade, performed on sedated children with an uninstrumented airway, are scarce. We performed a retrospective observational study of validated data from April 2014 to December 2020 in a paediatric cohort where the initial plan for anaesthetic management was sedation and caudal epidural without general anaesthesia or airway instrumentation. We examined success rates of this approach and rates of block failure and block-related complications. In total, 2547 patients ≤ 15 years of chronological age met inclusion criteria. Among the 2547 cases, including 453 (17.8%) former preterm patients, caudal-plus-sedation success rate was 95.1%. The primary anaesthesia plan was abandoned for general anaesthesia in 124 cases. Pain-related block failure in 83 (3.2%) was the most common cause for conversion. Complications included 39 respiratory events and 9 accidental spinal anaesthetics. Higher odds of pain-related block failure were associated with higher body weight (adjusted OR 1.063, 95%CI 1.035-1.092, p < 0.001) as well as with mid-abdominal surgery (e.g. umbilical hernia repair) (adjusted OR 15.11, 95%CI 7.69-29.7, p < 0.001), whereas extreme (< 28 weeks) former prematurity, regardless of chronological age, was associated with higher odds (adjusted OR 3.62, 95%CI 1.38-9.5, p = 0.009) for respiratory problems. Ultrasound-guided caudal epidural, performed under sedation with an uninstrumented airway, is an effective technique in the daily clinical routine. Higher body weight and mid-abdominal surgical procedures are risk factors for pain-related block failure. Patients who, regardless of chronological age, had been born as extreme preterm babies are at the highest risk for respiratory events.