Prolonged effect of bupivacaine hydrochloride after cuff release in i.v. regional anaesthesia.

Bupivacaine hydrochloride 0.25% and 0.50% solutions, were administered 115 times by the i.v. regional route to 64 surgical patients and in 38 subjects suffering from pain syndromes. The clinical effects were limb numbness up to 20 h following cuff release, while analgesia and weakness of the limb muscles were evident 5 h after the tourniquet. Clinical and electrophysiological findings revealed a dose relationship of the effects. Toxic signs were noted in three patients in whom the cuff was released in a one-step fashion. In 11 patients, mean arterial plasma concentrations of bupivacaine reached 3.7 micrograms ml-1 after administration of 0.5% bupivacaine 40 ml, 5 min after final cuff release, and decreased gradually thereafter. In selected conditions which do not require a bloodless field and in certain intractable pain states, i.v. regional anaesthesia with high-dose bupivacaine (200 mg of 0.5% solution) may be a simple and effective technique.