Evaluation of a transthecal digital nerve block in the injured pediatric patient

Digital anesthesia in the pediatric population has traditionally been accomplished using a ring block that requires multiple injections. A modified transthecal digital nerve block is a single-injection technique of the midproximal phalanx that has been shown to be technically simple and highly effective in adults.

To describe the success rate of the modified transthecal digital nerve block in children.

: A convenience sample of children requiring digital anesthesia for minor surgical procedures on the fingers or thumb at an urban tertiary-care pediatric emergency department were prospectively enrolled into the study. A transthecal digital nerve block was performed by injecting a 1:1 mixture of 1% lidocaine and 0.5% bupivicaine into the flexor tendon sheath at the midpoint between the proximal digital and the proximal interphalangeal joint creases. The volume of anesthetic was based on age. All nerve blocks were performed by 3 investigators trained in the procedure. Successful digital anesthesia was defined as complete loss of pinprick sensation on both the dorsal and palmar aspects of the digit and the ability to complete the anticipated minor surgical procedure without pain. Primary outcome measures were anesthesia success rate and pain score. Age-appropriate pain scale scores (Face, Legs, Activity, Cry, Consolability Scale, 0-3 years; Faces Scale, 4-7 years; and visual analog scale, > or =8 years) were recorded 5 minutes after injection. All patients were followed up for 6 months to assess for adverse events.

Between November 2003 and March 2004, 48 patients (50 digits) requiring digital anesthesia were enrolled into the study. The mean age of patients was 8.3 years (median, 7.6 years; range, 0.7-17.5 years). Twenty-four (50%) were boys and 30 whites (62.5%). Overall, the transthecal digital nerve block technique was successful in 47 (94%) of the 50 digits (95% confidence interval [CI], 83%-98%), including 37 (97%) of 38 fingers (95% CI, 85%-99%) and 10 (83%) of 12 thumbs (95% CI, 54%-96%). Forty-seven (94%) of the 50 digits had a recorded pain score of 0 five minutes after injection. Mean (SD) procedure time was 113 (24.8) seconds, and mean (SD) anesthetic volume was 2.13 (0.61) mL. No adverse events were reported.

The single-injection modified transthecal digital nerve block is a safe and effective method for digital anesthesia in children. These data confirm the applicability of transthecal digital nerve block for children with finger and thumb injuries that require minor surgical procedures.