The Ability of Infrared Thermography to Detect Successful Caudal Block in Children Undergoing Infra‐Umbilical Surgery

ABSTRACT Background Caudal epidural block is commonly used in pediatric surgeries but may fail due to anatomical variations or operator experience. Early recognition of block effectiveness is useful for timely pain management, improving outcomes and analgesic strategies. Aims This study aimed to assess the ability of infrared thermography to determine caudal block success in children. Methods In this prospective observational study, children (2–12 years) undergoing infra‐umbilical surgery received a caudal block after the induction of general anesthesia. FLIR C2 thermal camera was used to assess skin temperature at the dorsum of the foot, little toe, and suprapubic area at the baseline and 2, 5, 10, and 15 min after the block. Temperature change (Δ) was calculated as the difference from baseline. The primary outcome was the ability of Δ temperature at 10 min to detect a successful block, assessed via the area under the receiver operating characteristics curve (AUC). Results Data from 143 patients were analyzed; 29/143 (20%) patients had failed block. In the successful block group, the temperature increased over time and was significantly higher than that of the failed block group at 10 and 15 min. At 10 min, the AUC (95% confidence interval) for detecting successful block was higher at the dorsum of the foot (0.92 [0.86–0.96]) and little toe (0.87 [0.81–0.92]) compared to the suprapubic area (0.74 [0.66–0.81]). The positive predictive value for Δ temperature at the dorsum of the foot and little toe for detecting successful block was 95%–96% with cut‐offs of 1.2°C and 1.4°C, respectively. Conclusion In anesthetized children undergoing infra‐umbilical surgeries, infrared thermography can accurately confirm successful caudal block. Ten minutes after the block, an increase in the skin temperature by 1.2°C–1.4°C at the dorsum of the foot and little toe can confirm block success with 95%–96% accuracy.