Respiratory depression after epidural morphine in the postoperative period. Influence of posture

Twelve females scheduled for elective lower abdominal surgery received 4 mg of morphine by lumbar epidural injection for postoperative pain relief. The patients were divided into two groups nursed postoperatively in a supine or 45 degree elevated position, respectively. Mouth occlusion pressure during CO2 stimulation was used for the determination of respiratory depression, following epidural morphine. No significant difference in occlusion pressure was found between the two groups. Within the groups a significant reduction of the occlusion pressure was found when compared with the value obtained immediately before the administration of epidural morphine. However, compared with the value obtained the day before surgery, no significant reduction of the occlusion pressure was observed. It is concluded that the 45 degree elevated position does not protect against the occurrence of respiratory depression following epidural morphine.