Hi Jim,
While searching this site, medscape.com for another subject, I decided to look for what they might have on 'postoperative pain management'.
The following article illustrates the necessity of the RECOGNITION of patients' PAIN by surgeons and care providers, and the perils/side effects of the administration of systemic analgesics.
medscape.com
Outpatient Pain Management: Are You Part of the Solution or Part of the Problem?
Wayne H. Schwesinger, MD
Introduction
For the second consecutive year, a panel discussion held at the annual Clinical Congress of the American College of Surgeons addressed the continuing challenge of managing postoperative pain. Four expert panelists reviewed numerous aspects of the topic, with a special focus given to the problem of inadequate pain control following discharge from the hospital. All four agreed that better pain control should be possible in the hands of motivated and knowledgeable practitioners.
In his introductory remarks, the moderator H. David Reines, MD (Newton, Mass), observed that more than 50% of surgical patients still feel that the management of their postoperative pain is suboptimal.[1] In large measure, this can be explained by the relatively low priority given to the issue by many surgeons. The natural variability in pain perception, an unnatural concern about opioid addiction, patient stoicism, and lack of accountability for providing adequate pain control may also play a part in this widespread dissatisfaction with postoperative pain management.
Of special interest, several national initiatives have been created to address the problem of pain. However, to date, none appears to have had a significant effect. In 1992, an interdisciplinary panel sponsored by the US Department of Health and Human Services produced a clinical practice guideline for acute pain management by clinicians (AHCPR Pub. No. 92-0019) as well as a companion guide for patients themselves (AHCPR Pub. No. 92-0021).[2] The clinical practice guideline identifies three key requirements for the effective management of postoperative pain:
* Pain intensity and relief must be assessed and reassessed at regular intervals
* Patient preferences must be respected when determining methods to be used
* Each institution must develop an organized program to evaluate effectiveness
Unfortunately, available evidence suggests that these and other related recommendations have, so far, received indifferent support from most practitioners and institutions. However, a recent decision by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) to review compliance with pain assessment and management standards seems likely to have considerably more of an effect on future practice patterns. As such, it would be prudent to become familiar with and begin implementing the appropriate guidelines, since focused surveys will begin in 2001.
Meanwhile, new medicolegal threats have arisen. A recent courtroom challenge in Oregon alleges that physicians may be responsible for any excess suffering which results after insufficient analgesic regimen is provided after surgery. These issues are becoming especially important in the outpatient environment since much of surgical practice, including minimally invasive procedures, is now oriented toward the more rapid return of patients to their homes and jobs.
Pharmacology
The first panelist, James R. Macho, MD (San Francisco, Calif), focused on the pharmacology of current pain medications, using opioid analgesics as his reference point. In this regard, systemic opioids are known to act by stimulating one or more of the specific opioid receptors present in the brain and/or spinal cord, namely:
Receptor Effects
mu 1 analgesia, euphoria, pruritus, nausea, constipation
mu 2 respiratory depression, addiction, bradycardia
kappa spinal analgesia, sedation, pupillary constriction
delta analgesia, mood change, nausea
sigma dysphoria, hallucinations
For example, morphine sulfate, the prototypical opioid agonist, is selective for mu and kappa receptors. Thus, while morphine acts as a potent analgesic it is also associated with a number of adverse consequences, involving many different systems:
System Adverse Effects
Nervous drowsiness, mood changes, muscular rigidity
Pulmonary ventilatory depression
Cardiovascular vasodilatation (histamine release), bradycardia
Gastrointestinal decreased intestinal secretions and motility
Smooth Muscle constriction of urinary and biliary sphincters
Miscellaneous pruritus, urticaria
Tolerance and physical dependence can also develop as a result of opioid use, but these sequelae do not, in themselves, predict a significant risk of opiate abuse. In fact, when opiates are used primarily to control acute postoperative pain, the risk of addiction is negligible. Therefore, anxiety about the addiction potential should not inhibit the use of opiates and, as a result, unnecessarily forestall effective pain control.
A variety of other opiate agonists is now available. All exhibit properties similar to morphine but have somewhat different dose-response relationships and toxicity profiles. Fentanyl is a well-regarded synthetic opioid that has 75-100 times more analgesic potency than morphine, as well as a more rapid onset of action and shorter duration of effect. Like morphine, it can produce persistent or even recurrent respiratory depression when used in higher doses. Unlike morphine, it does not provoke histamine release and is therefore not as commonly associated with vascular dilatation and systemic hypotension.
Demerol, another synthetic opioid, is only one tenth as potent as morphine. Both the active form and its metabolite (normeperidine) can precipitate seizures or myoclonus by rapidly exciting the central nervous system. As such, all panelists agreed that its use should be strongly discouraged. Nonetheless, an informal survey of physicians in attendance indicated that its use was still relatively prevalent.
Administration
The method of opioid administration should be selected according to the specific needs and condition of the patient. Systemic administration can be provided easily by oral, intramuscular, or intravenous routes while regional (neuraxial) delivery requires access to specific compartments within the spinal canal. Regardless of the method used, opioid molecules must reach and bind to appropriate CNS receptors to exert their effect, a fact that requires they be able to cross the blood-brain barrier. As a result, the proximity of the drug delivery site to its target receptors helps to establish optimal dosing. For example, the dose of morphine administered intravenously must be 100 times higher than a dose delivered intrathecally to be therapeutically equivalent.
Three specialized methods of analgesic administration are also available. The first, preemptive analgesia, is based on the premise that preoperative neural blockade with opioids and/or local anesthetics will prevent or reduce postinjury stress and pain. Preliminary anecdotal evidence tends to confirm these advantages. However, subsequently only two of six randomized studies (total enrollment = 370 patients) confirmed a significant benefit. Better-designed clinical studies are needed to document any benefits of this approach.
Clinicians have had extensive experience with patient-controlled analgesia (PCA). This process permits patients to self-administer small doses of medication, usually an opioid, at relatively frequent intervals. Analgesic efficacy and patient satisfaction are enhanced compared with conventional PRN opioids. Morbidity and length of hospital stay, however, do not appear to be greatly affected by this method of administration. Optimal PCA usage requires appropriate patient education, a preliminary assessment, and regular evaluations while the patient is under treatment.
Finally, numerous studies have demonstrated that nearly complete pain relief can be obtained in most major abdominal and thoracic operations by using continuous epidural analgesia. This approach appears to facilitate the earlier resumption of eating and a faster return to normal daily activities; both effects can contribute to a shorter and more tolerable hospital stay. Still, universal adoption of this procedure has been restrained by the high costs and the slight risk of such serious complications such as epidural hematomas or abscesses.
Nonopioid Analgesics
Nonopioid local anesthetics may also play an important role in controlling postoperative pain. Site-specific local infiltration, regional nerve blocks, or neuraxial administration can moderate the pain experience by preventing the generation and conduction of nerve impulses from the point of tissue injury. The efficacy of these measures can be further enhanced by the coadministration of vasoconstricting agents such as epinephrine. While local anesthetics are generally safe and effective, major side effects have been reported. Side effects include such problems as tremors, cardiovascular abnormalities, and drug hypersensitivity. One popular local anesthetic, bupivacaine, has occasionally provoked severe ventricular arrhythmias, myocardial depression, and cardiac arrest, especially if an unplanned intravascular injection has occurred.
Because of the side effects of opioids and local anesthetics and the increasing growth of the outpatient paradigm, interest in classes of more "user-friendly" analgesics has grown. The most widely accepted of these new classes is the nonsteroidal anti-inflammatory drugs (NSAIDs). These agents relieve pain by blocking the action of cyclooxygenase, an enzyme complex that converts arachidonic acid to prostaglandins. In part, prostaglandins serve as crucial mediators of inflammation within the "inflammatory soup" present in regions of tissue injury. Thus, the NSAID effect is primarily local, although a minor central nervous system effect also has been postulated. Most NSAIDs are available only for oral use but one, ketorolac, can be administered intramuscularly and intravenously. In standard doses the analgesic potency of parenteral ketorolac is comparable to that of equivalent doses of morphine, but ketorolac does not cause the respiratory depression or decreased intestinal motility typical of all opioids. For this reason, its use as an adjunct together with morphine ("balanced analgesia") allows the administration of lower opioid doses and produces a consequent reduction in the risk of opioid-related respiratory and intestinal complications.
Still, there can be side effects with the use of ketorolac, especially in elderly patients. The most serious complications include renal failure, upper gastrointestinal ulceration, platelet dysfunction, and bronchospasm. Most of these side effects, however, can be avoided by careful attention to known risk factors and the use of proper dosing schedules. Of special interest is the recent discovery that cyclooxygenase is actually a composite of at least two separate isoenzymes each exerting different biological effects. COX-1 is a "house-keeping" enzyme responsible for protection of the gastric mucosa. Blockade of this enzyme can result in stomach ulceration. COX-2 is responsible for inflammation and pain and its selective blockade produces analgesia with minimal side effects. Understandably, considerable commercial interest is now driving the search for even more selective COX-2 inhibitors.
Multidisciplinary Approach to Pain Management
The next panelist, Edgar L. Ross, MD (Boston, Mass), strongly endorsed the need for a multidisciplinary approach in the management of pain. This concept is further amplified in electronic communications from the American Pain Society and the JCAHO. Several models of multidisciplinary pain teams have been developed in recent years. All require the full commitment of personnel in nursing, anesthesia, surgery, and primary care. Additional assistance is generally required of clerical, laboratory, and other support services. A number of related clinical activities contribute significantly to the successful multidisciplinary management of postoperative pain. These include:
* Preoperative assessment: establish rapport; train patient in use of a pain scale
* Intraoperative anesthesia and analgesia: consider preemptive/local measures
* Surgical techniques: optimize to avoid complications; minimize tissue damage
* Postoperative interventions: consider balanced/multimodal analgesia
* Assessments of effectiveness: use pain scale to optimize medication dose
* Discharge planning: reassure patient; anticipate tolerance to opioids
* Outpatient management: assess regularly; treat breakthrough pain aggressively
It seems likely that any or all of these elements will form the framework for the upcoming JCAHO review on pain management. This suggests that it may be advisable for clinicians to revise current hospital mission statements and quality assurance documents to reflect such standards.
Outpatient Management of Postoperative Pain
The final panelist, F. Todd Wetzel, MD (Chicago, Ill), focused on strategies for outpatient management of postoperative pain. He began with the utilitarian definition of pain promulgated by the International Association for the Study of Pain: "?an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." At least three overlapping components of pain are implicit within this definition:
* Nociceptive: This is caused by tissue damage and inflammation in response to trauma. The resulting pain is usually not well localized. It is opioid responsive.
* Neuropathic: This is caused by direct peripheral nerve or CNS injury. Pain is localized and often burning or shooting ("electric"). It responds poorly to opioids.
* Psychological: This component of pain is caused by cognitive and affective factors. Includes depression, drug-seeking.
These components are reflected to varying degrees in the three types of pain observed in surgical patients. Transient pain such as that seen with venipuncture is related to insignificant tissue damage and is not a major clinical problem. In contrast, acute pain, such as that often observed postoperatively, is predominantly nociceptive in origin but may also have minor or major neuropathic and psychological contributions. Initially, while moderate to severe tissue damage is still present, acute postoperative pain is likely to require potent therapy including systemic or neuraxial opioids.
At some interval before hospital discharge the patient must be transitioned from the parenteral/neuraxial agents to oral opioid agonists (ie, morphine, codeine, etc), mixed opioid agonists-antagonists (ie, pentazocine, butorphanol, etc) or nonopioid analgesics (ie, NSAIDs, acetaminophen, etc). The oral maintenance dose should be based on the patient?s observed in-house response, and not on generalized dose-response curves. Subsequently, provisions should be made for tapering the medication dosage as the pain subsides. Discharge planning should be used to address these issues and to assure realistic patient expectations. In particular, the patient should recognize that pain may persist for somewhat longer than expected (up to 6 weeks) and analgesic support will be available as needed for both baseline pain and any unexpected flare-ups.
Chronic pain should be suspected when pain persists in postoperative patients after the trauma of surgery has abated. While this type of postoperative pain begins with a nociceptive stimulus, its persistence usually results from a complex cascade of neuropathic and psychological inputs. The underlying causes are not usually clearly defined but it is likely that inadequate management of the initial acute pain contributes to the progression to a chronic pain state. Early diagnosis and effective treatment are a priority (albeit elusive) since chronic pain, once it occurs, can substantially reduce a patient's productivity and quality of life. A multidisciplinary approach is advisable from the outset.
Increasing interest in and research with postsurgical neuropathic pain has identified several variably successful therapies, both topical and invasive. These include:
* Capsaicin cream (derivative of chili peppers)
* Eutectic mixture of local anesthetics (EMLA)
* Transcutaneous electrical nerve stimulation (TENS)
* Spinal nerve stimulation
Research in these and other areas is ongoing and the development of new pharmaceuticals and delivery systems is anticipated.
Summary
This timely and well-delivered symposium appropriately restated the ethical imperative that adequate pain control should always be provided for the postoperative patient. Emphasis was placed on the role of education, various analgesics, and other adjunctive measures prior to and during the outpatient interval. The continuing challenge is to affirm a commitment on the part of all professionals to optimize this crucial aspect of patient care.
References
1. Reines HD, Macho JR, Ross EL, Wetzel FT. Outpatient pain management: are you part of the solution or part of the problem [panel discussion]. Program and abstracts of the 85th Clinical Congress of the American College of Surgeons; October 10-15, 1999; San Francisco, Calif.
2. Agency for Health Care Policy and Research. Acute Pain Management in Adults: Operative or Medical Procedures and Trauma (Quick Reference Guide for Clinicians). Rockville, Md: Agency for Health Care Policy and Research, Public Health Service, US Dept of Health and Human Services; February 1992. Publication No. AHCPR 92?0019.
Suggested Readings
* Buggy DJ, Smith G. Epidural anaesthesia and analgesia: better outcome after surgery? Growing evidence suggests so. BMJ. 1999;319:530-531.
* Car DB, Goudas LC. Acute pain. Lancet. 1999;353:2051-2058.
* Cousins MJ, ed. Acute and chronic pain. Int Anaesth Clin. 1997;35:1-213.
* D?Amours RH, Ferrante FM. Postoperative pain management. JOSPT. 1996;24:227-236.
* Frenette L. The acute pain service. Crit Care Clin. 1999;15:143-166.
* Hartmann T, Krenn CG, Preis C, Felfernig M. Organization and methods in postoperative pain therapy. Anaesthesia. 1998;53(suppl 2):47-49.
* Moon MR, Luchette FA, Gibson SW, Crews J, et al. Prospective, randomized comparison of epidural versus parenteral opioid analgesia in thoracic trauma. Ann Surg. 1999;229:684-692.
* Sandler AN, ed. Pain control in the perioperative patient. Surg Clin N Am. 1999;79:213-449.
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