VANCOUVER, B.C. Simple measures taken at the time of ambulatory surgery, such as the use of clonidine, can significantly reduce patients' postprocedure pain, Dr. Scott S. Reuben said at the annual meeting of the American Pain Society.
On a scientific front, "there has been an explosion in our understanding of pain management in the past 4 or 5 years," said Dr. Reuben, director of the acute pain service at Baystate Medical Center, Springfield, Mass., at which 35,000 ambulatory surgeries are performed each year.
At the same time, surveys suggest that pain care following ambulatory surgery is not getting better and may even be getting somewhat worse, as the number and types of surgery have grown, Dr. Reuben said.
"We're doing a horrible job managing postoerative pain," he said.
Preemptive techniques are key to addressing this situation because it is now known that pain control before and during a surgical procedure can prevent the trauma from causing central sensitization, which lowers the pain threshold in the postoperative period.
Good short-term pain control may even prevent chronic, postoperative pain from developing, he said.
Some of the methods used at his center to preempt central sensitization include:
▸ Local analgesia. Even with general anesthesia, local pain control is important during surgery, Dr. Reuben said. "General anesthesia does nothing to block central sensitization of the nervous system. Local anesthetics can."
At his center, local anesthesia for joint surgery includes a combination of agents, clonidine, bupivacaine, and morphine. The surgeons use ice as well.
▸ Clonidine. Alpha2-agonists used locally cause vasoconstriction that prevents dispersion of other local anesthetics, and that is probably one reason clonidine has been shown to increase the duration of local bupivacaine action, by 20%30% according to one study, Dr. Reuben said.
Clonidine itself also is an analgesic. It "has fantastic analgesic properties to control perioperative pain," he said.
▸ Opioids. The administration of an opioid before surgery acts centrally to prevent the hyperexcitability response produced by surgery, and this can mean less need for analgesics afterward. But more importantly, it is now known that there are local opioid receptors, and that even bone has them. "We have published about 12 studies on putting peripheral morphine in the knee for arthroscopy, with significant analgesic effects," Dr. Reuben said.
When morphine is used locally, very little is needed to control pain, and, as with clonidine, there appears to be a synergistic effect when it is used with other agents. Dr. Reuben's research group has shown that clonidine alone used locally produces significant analgesia for up to 7 hours, clonidine and bupivacaine produce analgesia for 10 hours, and clonidine, bupivacaine, and morphine combined produce 17 hours, he said.