Analgesic Effect of a Small Dose of Intrathecally Administrated Morphine for the Relief of Postoperative Pain

Intrathecal injections of 0.05 to 0.625mg morphine were given to 60 Japanese patients ranging in age from 16 to 76 years scheduled to undergo surgery of the lower abdomen or the lower extremities. Each patient experienced a considerable amelioration of the postoperative pain and duration of the effect was for 7 to more than 48 hours. Twenty-eight of fifty-three patients given over 0.1mg of morphine requested no analgesics, postoperatively. In cases of less than 0.4mg of morphine, there were no apparent side effects but two patients, given over 0.5mg of morphine (women aged 51 and 61 years) experienced decreased respiratory rate or carbon dioxide retention. These techniques of alleviating postoperative pain should be considered for application only in the presence of experts.