Prolonged local analgesia for inguinal herniorrhaphy with bupivacaine and dextran

In a randomised double-blind trial 40 patients undergoing unilateral inguinal herniorrhaphy were each locally anaesthetised with one of a series of 8 solutions. These contained bupivacaine, both with and without adrenaline, mixed with an equal volume of dextran 40, dextran 70, dextran 110, or saline. Significant prolongation of local analgesia was achieved with high-molecular-weight dextran and this was most consistently obtained when the solution used contained adrenaline. The possible influence of the pH of the solutions used, together with the ways in which dextran may affect the duration of action of bupivacaine are discussed.