Intravenous Morphine for Early Pain Relief in Patients with Acute Abdominal Pain

Objective: To determine whether morphine affects evaluation or outcome for patients with acute abdominal pain. Methods: Prospective, double-blind, placebo-controlled administration of morphine sulfate (MS) or normal saline (NS) in the setting of acute abdominal pain. The study was performed at a military ED with an annual census of 60, 000 visits. Patients ±18 years old who had abdominal pain for ± 48 hours were included. Patients who were allergic to MS or who had systolic blood pressures < 90 mm Hg were excluded. The physicians indicated a provisional diagnosis, a differential diagnosis, and a provisional disposition. Study solution was titrated to the patient's assessment of adequate analgesia (up to a volume equivalent of 20 mg of MS); pain response was monitored using a visual analog scale (VAS). The patients were followed until diagnosis occurred or symptoms resolved. Results: Of 75 patients enrolled, 71 completed the study; 35 patients received MS and 36 received NS. More than half (44; 62%) of the patients were admitted from the ED: 28 patients underwent surgery. The VAS pain level improved more for the MS group, 3.9 2 2.8 cm, than it did for the NS group, 0.8 ± 1.5 cm (p < 0.01). Study solution dose was less in the MS group than it was in the NS group, 1.5 ± 0.5 mL vs 1.8 ± 0.4 mL (p <0.01). There was no difference between the groups when comparing accuracy of provisional or differential diagnosis with that of final diagnosis. Differences between provisional and actual dispositions were the same in all groups. There were 3 diagnostic or management errors in each group. Conclusions: When compared with saline placebo, the administration of MS to patients with acute abdominal pain effectively relieved pain and did not alter the ability of physicians to accurately evaluate and treat patients. Key words: abdominal pain; analgesia; analgesics; emergency department; morphine; opiates; pain.