As new techniques and technologies shorten surgical time and decrease the morbidity of major procedures, postoperative pain can become the limiting factor when it comes to moving a procedure into the outpatient arena. Fortunately, acute pain control is advancing dramatically, and new strategies are not only bringing significant operations like radical mastectomy, ankle arthrodeses and total joint replacements into the outpatient setting, but they are helping to expedite fast-tracking of all outpatients. The major advance in postop pain control has been a shift away from treating post-op pain with prn opioids and toward pre-emptive, multimodal, customized pain prevention.

Pre-emptive analgesia
Theoretically, surgery 'hyperexcites' the spinal cord, and this barrage of neural stimuli can cause significant post-operative pain. Although clinical studies have yet to uniformly show that pre-emptive analgesia works, experts agree that blocking pain impulses before they begin is a hugely successful way to control post-op pain. Once the pain cascade starts to flow, they say, it can take a lot more medication to slow it down. "Probably the biggest impact I can have is to address pain before it starts," says Mark Hutchinson, MD, Associate Professor of Orthopedics and Sports Medicine and Director of Sports Medicine Services at the University of Illinois, Chicago. "Don't wait until the patient is in the recovery room and react to pain."

For many outpatient anesthesiologists, the cornerstone of pre-emptive analgesia is local/regional anesthesia using local anesthetics such as lidocaine, bupivicaine, ropivacaine or tetracaine. This targets the nociceptive impulses that transmit along the nerves while allowing the patient to breathe spontaneously and reducing the risk of PONV and drowsiness associated with general anesthesia. Although practitioners may use wound infiltration (e.g., injection of a local anesthetic into the portals before creating the pneumoperitoneum during laparoscopic cholecystectomy), IM injections, and/or regional blocks like spinals or epidurals, more and more anesthesiologists are believing in the benefits of "single-shot" peripheral nerve blocks for major upper limb, lower limb, and even chest and abdominal wall surgeries. "For patients not likely controlled with oral medications, peripheral nerve blocks can make the difference between discharge or admission," says Admir Hadzic, MD, PhD, Attending Anesthesiologist and Director of Regional Anesthesia with St. Luke's Hospital and Associate Professor of Clinical Anesthesiology with the College of Physicians and Surgeons in New York. In theory, peripheral nerve blocks-which target specific anatomic regions by anesthetizing a peripheral nerve, several peripheral nerves, or a plexus of peripheral nerves- are effective because they prevent the neural impulses from ever reaching the CNS.

At Duke University Medical Center, anesthesiologists are using long-acting ropivacaine/epinephrine peripheral nerve blocks to move procedures like hernia repairs, plastic surgery of the breast and radical mastectomies to the outpatient setting. Like many experts, they report that pain control with properly performed peripheral nerve blocks is nothing short of "spectacular" and that analgesia with the long-lasting local anesthetics lasts 15 to 20 hours from the block alone. In addition, says Susan M. Steele, MD, an anesthesiologist with the Duke University Medical Center's Ambulatory Surgery Center and Associate Clinical Professor with the Department of Anesthesiology, peripheral nerve blocks also expedite fast-tracking. "We sedate the patient and do the blocks before the patient even gets to the OR," she says. "The surgeon then starts immediately. Toward the end of surgery, we can turn off the propofol and recover the patient in the OR, bypassing stage one PACU. It's the best fast track."

Pain Assessment: Don't Just Treat a Number Although an aggressive pain prevention strategy using pre-emptive, local analgesia with a postoperative, multimodal oral dosing schedule can keep most patients relatively comfortable after surgery, experts warn against underestimating the importance of assessing pain during recovery. Even the best laid plans can fail to prevent breakthrough pain, say experts, because pain is very individual and unpredictable. Tolerance to pain medications can also be an issue. Opioid requirements, for example, may vary as much as four-fold among patients who undergo the same surgical procedure. Ironically, to improve your pain assessment skills, experts advise against relying too heavily on objective measures like the numeric pain intensity scale, the visual analogue scale, or the Wong-Baker FACES pain rating scale. In 1999, JCAHO issued standards requiring their accredited organizations to use assessment tools to quantify and thereby treat pain. Although this has helped spotlight the importance of pain assessment, say some experts, it can also complicate the process because inaccurate patient reports can lead to under- or over-prescribing. "Ultimately, pain is subjective, so objective measures are impossible," says Mark Hutchinson, MD, Associate Professor of Orthopedics and Sports Medicine and Director of Sports Medicine Services at the University of Illinois, Chicago. Rather, some pain physicians recommend relying on your own observational abilities and intuition to make the ultimate call. "If a patient tells me he is a number eight [on a scale of one to ten] yet proceeds to close his eyes and fall asleep, I know to trust my observation rather than his number," concludes J. P. Rathmell, MD, Associate Professor with the University of Vermont College of Medicine and Director of the Fletcher Allen Health Pain Service in Burlington, Vermont. "Don't treat a number; use your judgment."

Multimodal analgesia
Because people experience pain via numerous physiologic pathways, the most effective regimens are not only pre-emptive, but they are also "multimodal." That is, they target multiple physiologic levels. "The greatest advance has been the widespread acceptance and understanding of the principle of multimodal analgesia, meaning there is no single method, medication, or practice protocol that results in a perfect post-op pain control outcome," explains Dr. Hadzic. "Rather, a combination of various medications combined together produce the best result." For example, a multimodal regimen might include a peripheral nerve block, a non-steroidal anti-inflammatory drug (NSAID), and a post-operative opioid. While the nerve block targets the impulses transmitted through the peripheral nerves at the spinal cord level, the NSAID targets the site of tissue injury by blocking prostaglandin synthesis, and the opioid targets the perception of pain in the brain by binding to opioid receptors there.

Experts emphasize, however, that the key to making multimodal pain control work is proactive dosing. That is, they say, leave the traditional paradigm of prescribing for pain behind, and instead prescribe to prevent pain from returning after the regional or local analgesic wears off. J P. Rathmell, MD, Associate Professor with the University of Vermont College of Medicine and Director of the Fletcher Allen Health Pain Service in Burlington, Vt., advises a dosing schedule that includes a pre-emptive NSAID. "The best thing we have found is to give an NSAID pre-emptively, and then schedule the first dose of opioid before bedtime," he advises. "Then, as the block wears down, the patient will have some level of pain medication on board." To create the best dosing schedule for uninterrupted pain control, Alan P. Marco, MD, MMM, FACPE, anesthesiologist with the Medical College of Ohio, advises remaining cognizant of each agent's onset of action. For example, Dr. Marco may administer a small dose of a short-acting narcotic such as fentanyl toward the end of a case when using short-acting anesthetic agents intraoperatively. "Then, I give the oral outpatient medications when the patient is waking up," he says. "These take 45 minutes to an hour to reach their peak effect, so the fentanyl will help keep the patient comfortable in the interim."

The beauty of multimodal therapy is that it helps prevent over-prescribing of narcotics, and this promotes patient recovery. NSAIDs and opioids tend to work synergistically so, although patients may still need the analgesic potency of a narcotic, they won't need as much. "If one restricts treatment of post-operative pain to narcotics, you run into negative side effects such as PONV and somnolence, which can prolong discharge time, limit patients to the home environment, and have negative psychological effects," says Dr. Hadzic. Some patients prefer to endure pain rather than take too much narcotic, he says, but with a multimodal regimen, patients are more likely to take their pain medications.

Custom analgesia
Although its benefits may be many, a pre-emptive, multimodal pain control approach may not work if the practitioner neglects to carefully anticipate the degree of pain that will be associated with the procedure. For a growing handful of institutions, this means continuing the peripheral nerve block for up to 72 hours post-operatively for patients who undergo particularly painful procedures. Thanks to new equipment like nerve stimulators (for locating nerves), specialized catheters, and take-home pain pumps that allow the physician to pre-set flow rates and self-administered bolus intervals based on patient morbidities and weight, painful procedures once limited to the inpatient setting are now being done on an outpatient basis. "We are starting to see the limits of single-shot nerve blocks for some of the more painful procedures like acromioplasties and rotator cuff repairs in that they only get you to the middle of the night, wear off fairly quickly, and result in significant pain even when the patient already has a scheduled opioid regimen on board," explains Dr. Rathmell, who reports excellent results with a subacromial continuous infusion catheter.

At Duke, Dr. Steele and her colleagues continue approximately ten percent of their peripheral blocks for 48 to 72 hours. As a result, they have moved unilateral total knee and ankle replacements and ankle arthrodeses to the outpatient environment. "This [the continuous peripheral nerve block] is the mainstay [of post-op pain control]; then we administer around-the-clock NSAID plus acetaminophen and reserve narcotics for breakthrough pain due to associated PONV, sedation, itching, urinary retention, and possible respiratory depression," comments Dr. Steele. To date, the anesthesiologists at Duke have used approximately 2,500 peripheral continuous infusion blocks and report good success, claiming that actual drug costs are less than general anesthetic drug costs, PONV incidence and antiemetic use are down, and that there are no associated infections or reports of local anesthetic toxicity to date. The incidence of accidental injury as evidenced by grand mal seizure is from 0.2 to 0.7 percent, according to Dr. Steele, but there is no evidence of long-term chronic nerve deficits or other problems, although they are still tracking these data.

Still, experts agree that the peripheral continuous infusion technique is in its infancy, as no one yet knows what constitutes a toxic level of any one local anesthetic, whether the catheter insertion site will ultimately give rise to an inordinate number of infections, or whether the technique may result in long-term nerve complications. Further, notes Dr. Hadzic, the nerve location and sterile needle/catheter insertion technique requires "substantial expertise." Adds Dr. Hadzic: "It is well known that anesthesiologists are under-trained in peripheral nerve blocks. If training in single-shot techniques is inadequate, then training in continuous technique is almost nonexistent." Proper patient selection is also a concern, as is the need for extensive patient education, since patients go home with an insensate extremity. At Duke, patients must also learn how to remove the catheter themselves, just as they would a surgical drain.

When prescribing the post-op pain regimen, practitioners must also account for individual patients' tolerance to narcotics. More and more people take narcotics chronically for pain, and others may simply have an inherently high tolerance. For these patients, the post-operative period is not the time to cut back, say the experts. Rather, they say, prescribe the standard regimen on top of the patient's chronic regimen. "You may need to double the standard script," notes Dr. Rathmell. In addition, Dr. Marco advises shying away from dosages as the sole prescribing guide. "A big mistake is that we get hung up on the idea that the patient who has had 10 mg morphine and is still in pain is either drug-seeking or uncontrollable," he says. "The dose is just a number, and the patient who is hypertensive, tachycardic, and crying needs more help."

Managed expectations
Uninterrupted pain control not only improves efficiency and opens up the realm of possibilities for outpatient facilities, but it also improves patient comfort and boosts the patient's chances for rehabilitation. Experts say that even brief intervals of acute pain can induce long-term neuronal remodelling and sensitization, chronic pain, and psychological distress.

In the new era of post-op pain control, the key to success appears to be the three-fold strategy of blocking pain before it starts, hitting it at every level, and administering just enough to maintain the blockade without over-prescribing. Still, concludes Dr. Marco, it is also important to remember the importance of patient education. "There are enough data in the burgeoning area of alternative medical therapies like acupuncture, acupressure, and aromatherapy to show that one cannot dismiss this entirely as hokum," he concludes. "Attitude clearly makes a difference in recovery, tolerance and coping. Managing expectations may reduce pain and drug use further."

Contact Dianne Taylor at dherrin@speakeasy.net.