Pilot study of local anaesthetic peripheral nerve block in forefoot day case surgery: does it work better when administered before the start of the surgical procedure?

S. Chandrashekar, A. Watson

Introduction: The success of Day-case forefoot surgery depends on good post-operative pain relief to ensure that patients are confidently discharged home. We routinely perform all forefoot surgery as daycase procedure with pre-operative regional local anesthetic block with 0.5% Levo-Bupivacaine involving the superficial and deep peroneal, sural, posterior tibial and saphenous nerves. We hypothesized that pre-operative regional block has similar effectiveness if not better, compared to block administered after the surgical incision has been sutured.

Methods: 42 consecutive patients undergoing day-case bony forefoot surgery were recruited and randomized to receive regional local anesthetic block performed by senior author, with 20mls of 0.5% Levo-bupivacaine either before the surgical incision or after the surgical incision has been sutured. Patient and the member collecting data were blinded to the allocation. Intra-operative and post-operative analgesia was standardized in consultation with the anesthetists and all patients received general anesthesia.Post-operative visual analogue pain scores at 2 and 6 hours were collected. Data collection also included time at which they required rescue analgesia and the amount of analgesia used in the first 24 hrs.

Results: 3 patients required overnight hospital stay due to social reasons. Mean age of patients undergoing surgery was 59±1 years. Mean surgery time was 49±1 minutes in Post-operative group & 39±1 minutes in pre-operative group. Average of the sum of the pain scores at 2&6 hours were 2 and 1 respectively. Mean time to rescue analgesia was 9±1 hours in the post-operative group and 11±1 hours in the pre-operative group. The amount of non-opiate analgesia used after discharge was more in the post-operative group.

Conclusion: Pilot study power calculation suggests a sample size of at-least 67 patients to prove a statistical significance between groups. Results suggest Pre-operative regional anaesthetic block is better for longer pain relief in the initial 24 hours.