Continuous intravenous morphine for pain relief after abdominal surgery.

We studied prospectively 247 consecutive patients given morphine by continuous intravenous infusion for 24 h to provide pain relief following elective abdominal surgery. Using a dose of 1 mg/kg supplemented by additional intramuscular morphine 5 mg as necessary, only 26% required more than two additional intramuscular doses for discomfort. In 71 patients, the infusion was discontinued temporarily, mostly because of low respiratory rates. These patients were older (P less than 0.01), and their mean respiratory rate over the 24 h was significantly less (P less than 0.001) than those in whom the infusion was continuous. The technique was inexpensive, easy to use in a general surgical ward, and safe provided certain rules were observed.