The Spread Distance of Local Anesthetics in the Rectus Sheath Block in Children Aged 0-8 Years: A Retrospective Study.

Background The spread distance of local anesthetic (LA) in the rectus sheath block (RSB) should cover the planned surgical incision. However, there is limited data regarding the spread distance that can be covered by a certain volume in children. In this study, we aimed to investigate the spread distance of a particular volume of LA from a single injection point. Methodology This study included children aged 0-8 years (n = 41) who underwent umbilical or epigastric hernia repair, laparoscopic surgery, and surgeries via small midline incisions. The spread distances, which were measured via ultrasound guidance immediately after the block to ensure coverage of the entire planned surgical incision, were obtained from prospectively collected data about RSB. The spread distances in the craniocaudal direction on the right and left sides were compared and assessed for correlations with age, weight, LA volume, and sex. The need for a supplemental dose of LA in case of an incision exceeding the spread distance was also obtained from the records. Results The spread distances in the cranial and caudal directions from the injection point were 3.28 ± 1.04 cm and 3.74 ± 1.35 cm on the right (p = 0.066) and 3.44 ± 1.02 cm and 3.44 ± 1.33 cm on the left (p > 0.999), respectively. The total spread distances in the craniocaudal direction on the right and left were 5.55 ± 0.95 cm and 5.72 ± 1.28 cm in patients aged 0-2 years and 7.25 ± 1.92 cm and 7.39 ± 1.81 cm in patients aged at 2-8 years, respectively. The increase in the spread distance correlated with age, weight, and LA volume. None of the patients required a supplemental dose of LA, as the single-point injections covered the planned surgical incisions in all patients. Conclusions Similar spread distances in the cranial and caudal directions from a single injection point can be obtained with 0.5 mL/kg of the LA in 0-8-year-old children. The total spread distance in the craniocaudal direction was approximately 5 cm and 7 cm in children aged 0-2 years and 2-8 years, respectively.