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Trends in Post-Operative Pain Control
A look at four factors that have shaped the way we treat acute pain.
Tripti Kataria
Publish Date: October 10, 2007   |  Tags:   Anesthesia

Post-operative pain control is one of the most important factors that has enabled the growth of outpatient surgery. Post-op pain is the most common reason for discharge delays, hospital readmissions, calls to the surgeon or surgical facility and emergency room visits. To discharge patients on the day of surgery, facilitate a smooth recovery and help ensure that patients are satisfied with their overall surgical experience, we must control their pain.

The past five years have brought significant advances in post-op pain management methods, medications and technology. Let's explore the significant factors that have changed and will continue to shape the way we treat post-op pain.

Savvier patients
More than ever, patients are approaching elective surgery armed with information and expectations. They may have heard media stories about how minimally invasive surgery results in less pain, researched their particular procedure on the Internet, and talked to their friends and family members who've had outpatient surgery. Some patients may be taking medications to manage chronic pain, so they've already experienced powerful pain control.

As patients become more informed and proactive, clinicians will have to keep pace by educating them about all available pain management options and their side effects. We'll also have to manage patients' expectations and help them understand that although it may not be possible to prevent pain entirely, intractable pain is never acceptable, and they need to speak up if they're feeling uncomfortable.

The quality of pain control may soon affect a clinician's reimbursement. The Centers for Medicare and Medicaid Services, for example, has already developed a program that offers bonuses to physician groups that can demonstrate excellent patient outcomes, which may involve finding new ways to improve pain control.

Controversies over oral pain medications
Oral pain medications remain the gold standard in providing post-op pain relief. Clinicians have had a full armamentarium of medications at their disposal, including NSAIDs, COX-1 inhibitors, COX-2 inhibitors and opioids. In the last few months, however, three drugs - rofecoxib (Vioxx), celecoxib (Celebrex) and naproxen (Aleve) - have come under new scrutiny because of potentially dangerous side effects. Merck withdrew Vioxx from the market in September because of an increased risk of heart attack and stroke. In December, the National Institutes of Health halted a cancer trial involving Celebrex and an Alzheimer's trial involving Aleve because of similar risks. In response to these findings, the FDA recently issued a public health advisory recommending limited use of COX-2 inhibitors and other NSAIDs.

It's unclear what effects, if any, these preliminary findings will ultimately have on treating acute pain. Clinicians do prescribe Vioxx, Celebrex and Aleve to treat post-op pain, but, in general, we don't use these medications for longer than 10 days. As more data comes to light, however, we may start to re-examine our use of these drugs, especially in patients with cardiovascular risk factors. We'll also have to be prepared to answer questions and concerns about these medications from our patients.

Advances in peripheral nerve blocks
This regional anesthesia technique has gained favor for many reasons. Peripheral nerve blocks (PNBs) require minimal sedation, and many patients can go directly to Phase II recovery, which can shave up to an hour from the entire surgical stay. This contributes to smooth surgical flow and greater efficiency for the facility. Also, PNBs can provide from eight hours to 16 hours of continuous pain relief, delaying the need for adjunct medications. Patients tend to be highly satisfied with their pain relief and have minimal side effects, such as nausea and vomiting.

Not all anesthesiologists have the skills to administer PNBs, but with the advent of more training programs and regional anesthesia fellowships, more anesthesiologists will be acquiring these skills.

Both the medications and the techniques we use for PNBs have improved in recent years. A new generation of local anesthetics, which include ropivacaine and levobupivacaine, provide a larger margin of safety from cardiotoxicity. Also, we're now routinely using nerve stimulators to precisely locate the nerve, which has greatly improved our efficiency and success rate.

As PNBs become more widely used, we'll need to continue to improve patient education and counseling. We need to emphasize to patients and their caregivers that they need to treat pain preemptively, before the block wears off. The standard practice is to send patients home with three medications: an NSAID, a long-acting narcotic such as OxyContin and a short-acting narcotic such as Vicodin. They're told to take the long-acting narcotic every 12 hours, whether they feel pain or not. The short-acting narcotic is for breakthrough pain. The NSAID is another analgesic acting on pain via the COX receptor.'By using NSAIDs, you can cut down on the amount of narcotics patients use, both long- and short-acting. NSAIDs also help decrease inflammation.

Well-informed patients, longer-acting local anesthetics that relieve pain well into the recovery period and adjunct medications that can preemptively treat pain will all help advance the use of PNBs.

Rising popularity of portable pain pumps
In Australia and Europe, many physicians send ambulatory surgery patients (especially orthopedic) home with pain pumps that deliver local anesthetic, such as ropivacaine, directly to the surgical site. Proponents of take-home pumps say that they provide excellent long-term pain control, contribute to a shorter recovery and let patients take fewer opioids.

The use of take-home pain pumps has been slower to catch on in the United States. Until recently, pump technology was the limiting factor. Pumps were big and bulky, their medication reservoirs were small, and patients couldn't control how much medication they received (pumps would deliver the medication in a single continuous dose).

Now, manufacturers have developed more lightweight, disposable, user-friendly, portable pumps. They've also developed stimulating catheters, which let surgeons target the nerves and place the catheters precisely at the nerve site.

Still, a few barriers remain. Even for the most user-friendly pain pumps, patient selection is key. Ideally, patients should be cooperative, motivated and have a round-the-clock caregiver. Both the patient and the caregiver should understand how the pump works and be alert to potential problems, such as catheter migration, nerve injuries and infection.

In today's litigious society, many clinicians may not want to take the risk of implanting pain pumps, especially if they don't have motivated, savvy patients. But as manufacturers continue to refine pain pump technology, and physicians and patients become more familiar with them, this may change.

A driving factor
Experts estimate that from 65 percent to 70 percent of all elective surgeries are now performed on an outpatient basis, and that number is increasing. As market forces and physician and patient demands continue to drive the growth of outpatient surgery, better pain control will make that growth possible.

What's New in Pain Therapy
Here's an update on some emerging post-op pain products.

' Pokes. New technologies may make IV starts painless and keep the schedule going. LidoSite, Numby Stuff and NeedleBuster use electricity (iontophoresis) to drive the local anesthetic across the skin and numb it in as little as five minutes. Other new technologies include SonoPrep, which uses ultrasound to disrupt the outer layer of skin enough that the medications can penetrate it. Patients feel a slight buzzing or tingle but no pain, and the skin returns to normal in about a day. Another new technology uses a laser (Epiture Easytouch) to ablate the outer layer of skin to let OTC 4% lidocaine cream penetrate into the skin more quickly. All these products have potential use not only to reduce the pain from needles, but also to achieve anesthesia for superficial biopsies, aesthetic procedures and other treatments.

' Patches. Fentanyl patches (Duragesic) are marketed for chronic pain treatment, but their use is not advised for acute pain in patients who aren't opioid-tolerant. This is for two reasons. First, the potency is such that opioid-na've patients may have significant respiratory depression. Second, the patch first creates a depot of drug in the fatty tissue under the skin that delays the effect for as long as 18 hours to 24 hours. Also, that same depot means that if the patient suffers significant respiratory depression, simply removing the patch doesn't have an immediate effect; the depot must be depleted. You can use the Lidoderm patch for the treatment of the pain of postherpetic neuralgia. Some physicians will also use it for other neuralgic pain such as pain after nerve injury during surgery.

' Potential products. This section describes products that may not be available for patient use in the United States and/or are in clinical trials and are not approved by the FDA.

One of the more interesting products is a new, computer-controlled fentanyl patch that shows promise in replacing traditional intravenous patient-controlled analgesia (PCA). The E-TRANS fentanyl PTCS uses iontophoresis to drive 40mcg of fentanyl across the skin, making the time to effect fast enough to treat acute pain. You can program the credit-card-sized device much like a traditional PCA device to limit the maximum dose to a safe level. Another fentanyl product is AeroLEF, an aerosolized combination of free and liposome encapsulated fentanyl formulation. In phase one trials, it appears to have a rapid onset and prolonged duration of action, potentially allowing rapid pain relief without injections.

Another medication on the horizon is DepoDur. DepoDur uses liposomal encapsulated morphine for epidural injection to provide up to 48 hours of analgesia in preliminary studies. With the growing awareness of the risk of venous thrombosis, many surgeons routinely use anticoagulants post-operatively. This complicates using epidural analgesia because of the concern that when the catheter is removed, bleeding into the spinal column could possibly occur. This product would give the benefits of prolonged analgesia with a single injection, and could potentially be used in healthy, low-risk outpatients for prolonged analgesia. However, because each patient is different, if the standard dose results in respiratory depression, prolonged treatment and hospitalization may be necessary. More data is needed before it is clear whether or not this is a clinically significant issue.

- Alan P. Marco, MD, MMM

Dr. Marco ([email protected]) is chairman and associate professor in the department of anesthesiology at the Medical College of Ohio in Toledo.