Extradural administration of morphine and bupivacaine. A controlled comparison.

Analgesia, following operation, was provided by the extradural administration of morphine or bupivacaine in 24 patients, in a double-blind, randomized, cross-over study. Observations were made of vital signs, peak expiratory flow rate (PEFR), quality and duration of pain relief and the occurrence of adverse effects. Vital signs were little affected by morphine, but hypotension requiring active treatment occurred in three patients following the administration of bupivacaine. The PEFR was improved about equally by each drug, and the improvement was significant compared with control values (P less than 0.001). Pain relief as judged by the linear analogue scale was significantly better following bupivacaine than after morphine (P less than 0.001), but the pain score system, while showing effective pain relief in most patients with both drugs, did not demonstrate a significant difference between them. The duration of effect of morphine was significantly longer (P less than 0.05) than that of bupivacaine. Adverse effects, other than bupivacaine-induced hypotension, were not serious.