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Perioperative Pain Management in the Chronic Opioid User

Sasek, Cody MPAS, PA‐C, ATC

JBJS Journal of Orthopaedics for Physician Assistants: Fall 2016 - Volume 4 - Issue 4 - p 25–31
doi: 10.2106/JBJS.JOPA.16.00020
Articles

Perioperative pain management for patients who chronically consume opioids must be managed carefully to provide optimal pain control while avoiding negative outcomes. This review examines current pain management options in the perioperative period, including patient education and treatment planning; pharmacologic management with opioid pain medications; management with non‐opioids, including acetaminophen, nonsteroidal antiinflammatory drugs, N‐methyl‐D‐aspartate (NMDA) receptor antagonists, alpha‐adrenergic agonists, anxiolytics, and psychiatric medications; and use of local and regional anesthesia techniques.

1University of Missouri‐Kansas City, Kansas City, Missouri Investigation performed at the University of Missouri‐Kansas City, Kansas City, Missouri

This review also describes chronic opioid use and the pain response as it relates to a practical approach to managing surgical patients who chronically consume opioids.

Several groups, including the American Society of Anesthesiologists (ASA), have published expert consensus guidelines for the management of acute postoperative pain1. However, these guidelines and other sources do not specifically address the approach to patients who regularly use opioid medications for chronic, nonacute pain. The purpose of this article is to identify strategies to safely and effectively manage perioperative pain in the chronic opioid user.

In patients who consume opioids beyond periods of acute pain, the task of managing pain in a safe, appropriate, and effective manner is important. Between 2007 and 2012, prescriptions written for opioid medications increased by 7.3% in the U.S.2. In 2012, providers wrote 259 million opioid prescriptions, enough for every adult in the U.S. to have a bottle of pills3. In 2013, an estimated 1.9 million people abused or were dependent on prescription opioid pain medication4. Moreover, 46 people die in the U.S. every day from an overdose of prescription opioids5.

The concern for long‐term opioid ineffectiveness, the risk of side effects, and the potential for abuse recently led the U.S. Centers for Disease Control and Prevention (CDC) to publish new opioid prescribing guidelines that encourage decreased opioid use and increased use of other, non‐opioid treatment options. The U.S. Food and Drug Administration (FDA) has also taken action with the goals of increasing the focus on opioid education for providers and patients alike and developing additional pain management and abuse reduction programs. Additionally, the FDA has changed the classification of hydrocodone preparations from a Schedule‐III narcotic to a Schedule‐II narcotic.

The use of opioids to treat cancer‐related and acute pain, including postoperative pain, continues to be appropriate. However, in patients who are chronically treated with opioids for pain, there is less clarity in treatment choice, safety, and efficacy. The ability of providers to consistently manage this patient population, the risk of side effects, and the ever‐increasing concern for abuse and misuse potential all challenge the surgical care provider. Additionally, there continue to be uncertainties regarding the long‐term analgesic effectiveness of opioids.

Safe and effective pain management remains essential. It is known that high levels of postoperative pain are associated with greater risk of pulmonary and cardiovascular complications, remain the most common reason for delayed discharge or unplanned admission in ambulatory surgery patients, and lead to an extended recovery time following inpatient surgery6,7. In 1 study, length of hospitalization following total knee arthroplasty was 4.3 days in chronic opioid users compared with 3.4 days in patients who were opioid naive8. In addition, it has been shown that high levels of postoperative pain are associated with an increased risk of chronic pain as a consequence of surgery9,10 and lead to increased health‐care costs11.

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Pain Response

The presence of preoperative pain and high anxiety have been well validated as predictors of early, more severe postoperative pain. Other predictors of increased pain and analgesic requirement are demographic factors such as age, psychological conditions (including depression and anxiety), preexisting pain conditions, and the preoperative use of opioids12. Those with both preoperative chronic pain and opioid consumption consistently demonstrate higher pain readings postoperatively with both intravenous (IV) patient‐controlled analgesia (PCA) and epidural anesthesia13.

Traditionally, the increasing need for opioids by chronic users of these medications was largely attributed to the development of tolerance. Recent evidence suggests that opioid‐induced hyperalgesia plays a role as well14. Research continues to define the neurophysiologic and pharmacologic changes associated with this apparently distinct phenomenon. Current theories suggest opioidinduced hyperalgesia is a result of neuroplastic changes that lead to altered nociceptive signaling and sensitization. Over time, these changes lead to a paradoxical increase in pain sensitivity despite increasing opioid dosage. Several studies have examined this relationship by observing the pain response in patients given either high or low doses of opioids intraoperatively. The higherdose group paradoxically experienced greater pain and had increased opioid consumption postoperatively15,16.

Researchers continue to examine the relationship between preoperative opioid use and postoperative pain. In 1 study, cancer patients who had been consuming opioids chronically and subsequently underwent surgery required 3 times more morphine by epidural infusion and 4 times more morphine given as IV boluses than opioidnaive patients17. Rapp et al.18 found that patients who take opioids regularly have a threefold increase in postoperative opioid need, while still experiencing greater pain.

As previously noted, pain response is also mediated by psychological factors, namely anxiety. Patients with chronic pain have been shown to score substantially higher than average on the hypochondria and hysteria scales of the Minnesota Multiphasic Personality Inventory‐2 (MMPI‐2). The MMPI‐2 health concerns and depression scales also showed substantial elevations with patients who are in chronic pain19. It is important to appreciate the role of anxiety, other psychological factors, and psychiatric disorders so that treatment (e.g., cognitive behavioral approaches and possible addition of anxiolytics or antidepressants) can be directed to these contributing factors.

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Approach to the Patient

Preoperative

When patients with chronic pain are admitted for surgical procedures, it is essential to recognize the need for continuation of the patient's routine pain‐management regimen as able, and to plan for additional acute postoperative pain requirements. Understanding the patient's current pain medication plan facilitates the development of a safe and effective postoperative strategy to avoid both overuse and withdrawal.

In addition to a routine preoperative medical evaluation and clearance, it can also be helpful to complete a preoperative pain assessment. Such an evaluation helps to establish expectations for the patient and helps the provider to understand a patient's pain history more completely. As part of this assessment, specific information regarding current medications, including the total amount of opioids consumed daily, provocative and palliative factors, history of side effects and medical allergies, and any additional therapies or treatments that have been attempted should be obtained. This will provide information to assess potential opioid tolerance and the likelihood of withdrawal. Preoperative genetic testing has also been a more recent potential evaluation tool to help predict a patient's response to specific opioids and antidepressants20. In addition to patients who receive chronic opioids, patients who might specifically benefit from a formal preoperative pain assessment are shown in Table I.

Preoperative counseling providing supportive and educational conversations prior to surgery may reduce anxiety and improve pain control. Educating the patient on available analgesic techniques may also provide the patient with better, more realistic expectations21. This approach needs additional study because a recent meta‐analysis showed no pain benefit from such conversations in patients undergoing hip and knee replacement surgery22. However, this may represent an additional means to manage pain proactively in the preoperative phase.

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Perioperative

Although there are not specific guidelines for managing pain in the immediate perioperative phase in this population, principles should include minimizing the disruption to the usual daily medication regimen, increasing opioid dosing for acute postoperative pain (this may require a doubled dose or even higher compared with opioid‐naive patients), and use of a multimodal approach. Specific plans for returning to baseline treatment following the postoperative period are also important. The approach should err on the side of proactive, rather than reactive, efforts to control pain.

The patient's usual opioid routine generally should be continued up until the immediate preoperative period, including long‐acting opioid formulations that often can be taken the morning of surgery. For patients who require a longer fasting period prior to surgery, parenteral administration of pain medications may be necessary. Recent research has demonstrated that pain patches, such as fentanyl and buprenorphine, are safe for use through the perioperative period when patients have been using them preoperatively23. Care should be taken with pain‐patch use because drug absorption increases with elevated skin temperature. Patients with fever or those warmed in the intraoperative period should be monitored carefully.

To provide the patient's usual baseline opioid dosing, several options are available. Oral medications can be continued if possible, or the patient's usual opioid medications can be given parenterally by converting the oral dose into a morphine‐equivalent dose (Fig. 1)24. It should be noted that equivalent doses of opioids are not exact or consistent among patients because of variable cross‐tolerance between opioids. Current recommendations suggest starting at 50% of the equianalgesic dose when moving from one opioid to another25. This helps to protect against withdrawal as well as overdosing. If additional analgesia is needed, which is likely, a PCA pump is one option that gives the patient a greater sense of control, potentially leading to lower anxiety and pain levels. Providers must be cautious and judicious when utilizing PCA, however, specifically with regard to concern for respiratory depression26.

Long‐acting opioids are generally more appropriate in the perioperative period because the sole use of short‐acting formulations may result in poorly controlled pain, the need for catch‐up dosing secondary to delays in administration of medication, hesitance by staff to give doses that can be 2 to 4 times greater than in opioid‐naive patients, and the potential for withdrawal. Generally, at least half of the preoperative opioid dose is needed to prevent withdrawal symptoms. Risk for withdrawal also makes the initiation of opioid agonists, such as buprenorphine or methadone, unadvisable in the immediate perioperative period.

According to research by Fu et al.27, patients undergoing total knee arthroplasty treated with a multimodal pain management approach, including oral celecoxib and tramadol and intra‐articular injections of morphine, ropivicaine, epinephrine, and betamethasone, had decreased narcotic use, improved pain scores, and earlier attainment of physical therapy milestones. Nausea and vomiting were reduced in the treatment group with all other complication rates being similar. Comparable findings were seen in a study with patients who had undergone total hip as well as total knee arthroplasty28.

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Postoperative

Following the acute postoperative period, the patient should be transitioned from any IV opioids to oral dose (PO) equivalents, with one‐half to two‐thirds of these dosages in long‐acting formulations. The remaining dosage should be in short‐acting opioids or tramadol for breakthrough pain. Time parameters should be placed on the use of postoperative medications to reduce the risk for misuse, abuse, and ongoing pain‐management issues. Establishing optimal dosing of pain medications should be done in consultation with a pain‐management specialist to avoid multiple providers prescribing without coordination. The general approach to preoperative, perioperative, and postoperative pain management is outlined in Figure 2.

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Alternative Approaches

NSAIDs play a valuable role in the multimodal approach to pain management because their efficacy and side effect profile are well known and they have a unique mechanism of action compared with opioids. Care should be taken with NSAID use in patients with renal impairment, or a history of gastric ulcer, or where there is concern for delay in bone‐healing. More selective cyclooxygenase‐2 (COX‐2) inhibitors, such as celecoxib, have been shown to be less likely to delay bone‐healing and also have minimal impact on coagulation, although there is concern regarding an increase in cardiovascular events29. Yu‐Min Huang et al.30 found that in patients with total knee replacement, perioperative celecoxib substantially improved postoperative resting pain scores, reduced opioid consumption, and promoted greater active range of motion in the first 3 days after total knee arthroplasty, without increasing the risks of bleeding.

Perioperative oral or intravenous acetaminophen has been shown to be effective in reducing postoperative pain and opioid consumption31. Additionally, acetaminophen does not substantially affect coagulation or renal function, or have the gastrointestinal implications of NSAIDs. Studies have also shown that NSAIDs given concurrently with acetaminophen control pain more effectively than either medication alone32,33.

Several N‐methyl‐D‐aspartate (NMDA) receptor antagonists (including ketamine, memantine, amantadine, and dextromethorphan) and medications such as magnesium have been used in the perioperative period in the chronicpain patient population. Most, but not all, studies have shown that perioperative ketamine reduces pain and the need for opioids postoperatively—by as much as 70% in the first 24 hours postoperatively according to 1 study34. It is believed that ketamine works by direct analgesic effects, but also by preventing sensitization of nociceptive pathways, potentially reversing or slowing tolerance and opioid‐induced hyperalgesia. Because of a threefold increase in the risk for unpleasant dreams with subanesthetic doses of ketamine, coadministration with a medication such as midazolam (Versed) may be warranted35. Ketamine appears most beneficial in patients who have had turbulent postoperative pain relief previously or in those who are on very high doses of opioids36.

Additional adjunctive medications can help reduce pain in specific populations. The anticonvulsant gabapentin has been shown to reduce pain scores and opioid requirements37, but is not without risks, including dizziness, edema, and dry mouth. Because of the risk of seizure, gabapentin must be carefully titrated with initiation and when discontinuing. Alphaadrenergic receptor agonists, such as clonidine, have a unique role as they have been shown to alleviate opioid withdrawal symptoms as well as treat pain38. Antidepressants, specifically duloxetine (with its indications for depressive symptoms, anxiety, and pain), anxiolytics (e.g., benzodiazepines), and antihistamines (including hydroxyzine) have potential roles in the control of pain‐related psychological symptoms. It should be noted that there is concern regarding use of selective serotonin reuptake inhibitors (SSRIs) and increased risk of postoperative bleeding39. Also, concurrent use of SSRIs and tramadol has been shown to increase the risk of serotonin syndrome40.

Local and regional anesthesia techniques also can aid in postoperative pain management. The benefits of these techniques include complete or near‐complete analgesia, reduction of the immediate postoperative need for pain medications when this need is typically greatest, and possible avoidance of the pitfalls of increased opioid use in the short term. In a study of patients undergoing laparoscopic gynecological surgery, those who received infiltration of local anesthetic in the surgical wound required from 4 to 17 times less opioids in the first 24 postoperative hours41. In another study examining patients who had undergone total knee arthroplasty, use of periarticular injections demonstrated similar pain scores when compared with femoral nerve blocks, but the femoral block group used less narcotic in the first 24 hours following surgery42.

Peripheral nerve blocks for the upper or lower extremities can serve as helpful adjuncts when surgery involves the extremities. These procedures can be done as a single bolus of local anesthetic or with the placement of catheters, which allow for the ongoing administration of anesthetic. Intra‐articular administration of local anesthetics can be used, but should be approached carefully secondary to the potential chondrolytic effects of many anesthetics. The use of peripheral nerve blocks in the upper or lower extremities has been shown to improve postoperative pain control, decrease opioid consumption, and improve patient satisfaction postoperatively43,44. Similar benefits have been seen with epidural anesthesia45.

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Conclusion

Because of the implications of perioperative pain in the surgical setting for the chronic opioid user, pain should be managed carefully in this population. This should be done on an individual basis and involve patients in the decision‐making process when possible. Patients with chronic pain who use opioids will likely need additional treatment beyond their baseline opioid consumption. The perioperative period is not the time to reduce opioid consumption. Both poor pain control and opioid withdrawal can have substantial consequences for these patients.

A multimodal approach to this population is likely most effective. The patient's baseline opioid equivalent should be administered while taking advantage of alternate treatment approaches. This can include local, regional, and epidural anesthesia, as well as non‐opioid pharmacologic treatment, including NSAIDS, anxiolytics, antidepressants, ketamine, and other analgesics. It is important to recognize that these additional medications are not without risk of side effects and drug interactions. However, substantial changes to opioid medication dosages also present risks, including overdose, withdrawal, and poorer surgical outcomes.

Without clear best practices, the provider's clinical judgment must balance the risks and benefits associated with each treatment option to provide the most effective and safe perioperative pain control. Because a compelling evidence base does not exist and this topic is so clinically relevant46, there is need for additional research to develop best practices for surgical patients who chronically consume opioids.

Disclosure: The author indicated that no external funding was received for any aspect of this work.

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