While opioids have long been a mainstay of general anesthesia, a variety of ill effects and adverse socio-cultural influences have led to intense efforts to restrain or even proscribe their use. Though few anesthesiologists profess to be able to avoid opioids completely for surgical procedures, a strong effort is currently being made in the specialty to reduce the amount of opioids used during surgical procedures, in a setting in which they once were considered to be an indispensable central component of the anesthetic.
Reducing Opioid Use Through Substitution
How can we reduce opioid use in the operating room? There are several opportunities that clinicians have in the perioperative period. One method is to substitute other medications for opioids, in order to ameliorate the adverse effects that accompany drugs in the opioid class. This is termed “multi-modal analgesia,” a program that has become a component of many anesthetic plans, and perhaps the majority of them.
Opioids work at specific receptors in the brain and spinal cord (and, to a lesser degree, in other parts of the body). This activity unifies them as a specific drug class. But a variety of other drug families can impact the initiation of pain or its perception, and these agents can be utilized in concert with smaller doses of opioids during surgery, or even in lieu of them.
Some such drugs are quite familiar to all of us, including acetaminophen (the active drug in Tylenol), which provides a degree of pain relief as well as a weak anti-inflammatory effect.
Nonsteroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen, are in most medicine cabinets, and likewise relieve pain, primarily by checking the inflammatory process at the site of injury. By stopping the generation of molecules called prostaglandins, NSAIDS reduce the migration of inflammatory cells to sites of cellular damage, which also attenuates the release of inflammatory mediation molecules, responsible for pain, swelling, redness and a proliferation of the response.
It is worth noting that inflammation is a major component of the pain-generating injury response that occurs where tissue injury is registered, including surgical injury. Control of this inflammation also helps to control pain. Steroids represent yet another group of medications that contribute to meaningful pain relief and control of inflammation. While their anti-inflammatory benefits may take several hours to occur, they nonetheless are incorporated into many anesthetics, and yield benefits in the postoperative period.
Other drug classes that are frequently incorporated into MMA include antagonists of a binding site on cells in the central nervous system referred to as “NMDA receptors,” which enable and perpetuate pain impulses—drugs such as ketamine and the cation magnesium.
Still another useful class of medications for attenuation of the pain of surgical incision is referred to as alpha-2-agonists, which bind peripherally and centrally to receptors that enhance pain relief, examples of which are clonidine and dexmedetomidine.
Local anesthetic drugs, familiar as the “novocaine” used by dentists, or lidocaine injected to numb a wound for suturing in the emergency department, are essential elements of multimodal analgesia. These agents can be infiltrated into the tissues near the incision by the surgeon (“local infiltration analgesia”), administered as intravenous infusions during and for several days after surgery, or injected near nerve trunks or plexuses to provide interruption of pain transmission, often termed a “nerve block.” Their versatility has resulted in dramatic increases in their use in the past ten or fifteen years.
Pushing For Multimodal Analgesia
Though opioids have proven valuable in anesthesia and pain management for decades past, anesthesia providers now have a substantial array of non-opioids to choose from to help reduce overall opioid doses while still effectively controlling pain. By substituting these other analgesic agents for opioids, patients are subjected to considerably fewer opioid-related side effects, such as nausea, vomiting, constipation and itching.
More importantly, reducing opioids can also reduce life-threatening episodes of respiratory depression in the postoperative period. And of course, fewer opioids may translate into less potential for dependence, abuse and addiction. Accordingly, it is not surprising that multimodal analgesia is a hallmark of modern anesthesia care.
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