Opioids: more to learn, improvements to be made.

OPIOIDS are among the most widely used drugs in medicine and are used for the management of acute and chronic pain from a wide variety of disorders. A report in the current issue of ANESTHESIOLOGY by Aubrun et al. affords an opportunity to reconsider and reexamine the role of opioids in pain management and also to review the realistic expectations for pain relief and relief of other symptoms for patients receiving opioids for acute pain. It is worthwhile to begin by defending the uses of these drugs. Opioids are important components of many general anesthetic regimens. They have essential roles in the management of acute pain. For the majority of patients with cancer and sickle cell disease, and for patients in palliative care, opioids are effective in providing pain relief with a tolerable side-effect profile, particularly if mild-to-moderate degrees of sedation are considered acceptable. The risk of addiction in hospitalized patients who receive opioids for pain is quite low. Contrary to common belief, opioids also provide analgesia for some patients with neuropathic pain and even for a subgroup of patients with phantom limb pain after amputation. Aubrun et al. examined morphine administration and pain relief in more than 3000 postoperative patients in the PACU, using a standardized titration procedure. Specifically, pain was assessed (using a visual analog scale [VAS] of 0–100) as quickly as possible after arrival in the PACU, and if the reported pain intensity was greater than 30, 3 mg of morphine was given. Assessment and treatment was repeated every 5 min until the reported VAS was 30 or less. Drug administration was stopped before the achievement of adequate pain relief only for respiratory depression (respiratory rate 12 bpm) or other serious events (e.g., hypotension, vomiting). Note that sedation was not considered a serious side effect. These investigators then examined the relationship between the initial pain score and amount of morphine required to achieve comfort. They reached several conclusions: 1. Patients with higher initial VAS pain scores required more incremental doses of morphine to reach an acceptable pain score (VAS 30). 2. There was a marked variation in the number of morphine doses required to produce comfort. The median dose to achieve a VAS of 30 or less was 0.17 mg/kg. 3. In general, VAS scores of 70 or more should be regarded as indicative of severe pain. 4. Most patients with a VAS score of 50 will usually require only one additional dose of morphine to report a VAS of 30 or less.