Narcotics for acute postoperative pain. Is intramuscular administration passé?

Intramuscular (IM) injection of narcotic has been the mainstay of postoperative analgesia. However, problems inherent in IM administration--pulmonary dysfunction and inadequate pain control due to variable peak levels of drug concentration and variable absorption rate--have resulted in continuing efforts to find a more desirable method of administration. Intravenous (IV) infusion on a continuous or self-administered intermittent basis controls pain more effectively than IM injection. The total amount of drug required is significantly less and pulmonary dysfunction seems to occur less frequently. Some investigators are studying injection of narcotic into the epidural or subarachnoid space of the spine as a means of providing postoperative analgesia. This method provides an unusually intense, prolonged, and segmental analgesic action, as well as greater improvement in respiratory dynamics than with IV infusion. Although the advantages of the IV and spinal methods seem to outweigh the disadvantages, further research is needed before they can be recommended as alternatives to the standard IM method used to control postoperative pain.