The analgesic efficacy of forearm versus upper arm intravenous regional anesthesia (Bier's block): A randomized controlled non-inferiority trial

Study objective: This study aimed to assess if a forearm (FA) intravenous regional anesthesia (IVRA) with a lower, less toxic, local anesthetic dosage is non-inferior to an upper arm (UA) IVRA in providing a surgical block in patients undergoing hand and wrist surgery.

Design: Observer-blinded, randomized non-inferiority study.

Setting: Operating room.

Patients: 280 patients undergoing hand surgery were randomly assigned to UA IVRA (n = 140) or FA IVRA (n = 140).

Interventions: Forearm IVRA or upper arm IVRA in patients undergoing hand and wrist surgery.

Measurements: The primary outcome was block success rate of both techniques. Block success was defined as no need of additional analgesics. A second, alternative non-inferiority outcome was defined as no need of conversion to general anesthesia. A difference in success rate of <5% was considered non-inferior. Secondary endpoints were tourniquet pain measured with a Numerical Rating Scale (0-10), satisfaction of patients and surgeons, onset time, surgical time and total OR time.

Main results: Non-inferiority of block success rate, defined as no need of additional analgesics or conversion to general anesthesia was inconclusive (5.24%, 95% CI:-4.34%,+14.82%). Non-inferiority of no need of conversion to general anesthesia was confirmed (+0.73%, 95% CI:-0.69%,+2.15%). No differences were observed in onset time (FA: 5 (5, 8) vs UA: 6 (5, 7) min, p = 0.74), surgical time (FA: 8 (5, 12) vs UA: 7 (5, 11) min, p = 0.71), nor total OR stay time (FA: 34 (27, 41) vs UA: 35 (32, 39) min, p = 0.09). Tourniquet pain after 10 min was significantly lower after FA IVRA compared to UA IVRA (FA: 2.00 (0.00, 4.00) vs UA: 3.00 (1.00,5.00) min, p = 0.003).

Conclusion: We failed to demonstrate non-inferiority of forearm IVRA with a lower dosage of LA in providing a surgical block without rescue opioids and LA. Non-inferiority of no need of conversion to general anesthesia was confirmed.