Peridural administration of morphine, with or without adrenalin, for postoperative analgesia

Morphine was administered by the peridural route, in doses of 2 to 6 mg, without and with adrenalin 1/200,000, to 197 patients undergoing various surgical procedures under peridural anesthesia, with a view to lower post-operative pain. The evaluation of the effect was estimated subjectively, with the aid of a visual analogue scale and was also based on the demand for analgesia. The latency time appeared to be long: 1 hour. The overall mean duration of action is 16.25 h. The efficiency is related to the type of operation: 2-3 mg doses injected after the operation are effective in only about 50% of laparotomies and orthopedic procedures, whereas with soft tissue surgery or ano-perineal and gynecological surgery efficiency is higher (83.33% and 88.23% respectively). The injection given during the operation is more efficient, but urinary retention also seems to increase. No respiratory, circulatory or motor depression has been observed. The most untoward effects are nausea and vomiting (32.99%), urinary retention (25.40%), itching (20.30%). Combination with adrenalin does not improve the efficiency of the analgesia and secondary effects tend to be enhanced, especially urinary retention (53.57%). The spinal mediation of the effects of morphine and its access to supraspinal structures are discussed.