What do systematic reviews say?

Double vs single‐injection technique

Double showed no clear difference in secondary analgesia failure ‐ tourniquet pain compared with single‐injection technique (moderate certainty).

• Single, double or multiple‐injection techniques for non‐ultrasound guided axillary brachial plexus block in adults… 2016 · Cochrane Headline outcomes only
  RR 0.58 [0.22, 1.52]
  2 studies · 104 participants
  Moderate