Pain management in the elderly remains one of the most challenging issues for the podiatric surgeon. As life expectancy continues to advance, more geriatric patients will undergo surgery. While these patients may undergo these procedures to help facilitate independence and a better quality of life, one must carefully weigh the risks and benefits of surgical intervention in this patient population.
Regardless of the success of the given surgical procedure, one may still encounter significant tissue damage and the subsequent release of pain and inflammatory mediators.1 While the principles of pain management remain fundamentally consistent across all age groups, there are unique challenges when it comes to alleviating the pain of elderly surgical patients.
Indeed, there are a number of barriers and misconceptions that can contribute to the inadequate assessment and treatment of pain in seniors. Factors affecting pain control include cognitive impairment, altered communication and misunderstanding regarding the use and effects of analgesics, especially narcotics.
Also keep in mind that older adults may not report pain due to the fear of further tests, the addition of supplemental medications or feeling intimidated by the knowledge and authority of their doctor.2
With these points in mind, let us take a closer look at pharmacologic intervention for acute postoperative pain in the geriatric patient.
Most clinicians are familiar with the conceptional guide that was originally developed by the World Health Organization (WHO) for malignant pain. This guide is now widely referred to when physicians are treating nonmalignant pain.3 It provides a time-tested, three-step approach to the rational selection of analgesics in an ascending fashion. Classically, aspirin, acetaminophen and NSAIDs comprise the first step for treating mild pain and there is a progression to opioids for moderate to severe pain.
Acetaminophen is considered to be the agent of choice for managing mild to moderate pain in older adults.4 It is safe and effective in this age group when one uses it within normal dosing parameters. While the risk for hepatotoxicity is well known, these effects are primarily dose-dependent as opposed to being caused by altered pharmacokinetics. Acetaminophen is metabolized by phase II conjugation, which remains essentially unchanged with advancing age. Although the maximum adult recommended dose is 4 g/day, some gerontologists recommend limiting the intake to 3,200 mg/day.5 Podiatrists should be aware that older adults may place themselves at risk in exceeding their total daily intake if they forget to report or inadvertently consume over-the-counter acetaminophen in combination products such as those for headache or cold relief.
When it comes to prescribing NSAIDs during the preoperative period, they do offer the benefits of an opioid-sparing effect and the potential to reduce postoperative inflammation. However, these medications are not without risks. The multitude of potential complications affecting the gastrointestinal, renal, hepatic, cardiovascular, central nervous system and hematologic systems has been well documented. The risk of these side effects is higher in the elderly population due to their widespread use of NSAID medications. Approximately half of all NSAID prescriptions are written for patients beyond 60 years of age.6 These risks become more significant when they are combined with the decrease in activity of hepatic phase I oxidation and reduction reactions leading to drug accumulation, as well as diminished kidney function that results in decreased renal elimination.7
Ibuprofen is a short-acting agent that has been deemed appropriate for mild to moderate pain in seniors. As a nonselective NSAID, there are still concerns for GI effects as well as the potential for prolonged bleeding postoperatively due to its anti-platelet activity. The COX-2 specific inhibitor celecoxib provides an improved GI safety profile without platelet inhibitory effects but offers little difference in analgesic efficacy over conventional NSAIDs. In light of the current cardiovascular concerns with COX-2 selective agents, using a COX-2 preferential inhibitor such as nabumetone, which is a nonacid derivative, is also considered a suitable alternative in the elderly.
Ketorolac is available in a parenteral formulation and is effective for the short-term management of moderately severe pain that requires analgesia at the opioid level for up to five days. One should reduce the dosage to 15 mg IV or 30 mg IM in those over the age of 65.
While nonacetylated salicylates, such as salsalate, diflunisal and choline magnesium salicylate, are weak COX-1 inhibitors that have been mentioned as alternatives, numerous clinicians have found them to be less efficacious than COX-2 inhibitors. Naproxen is among the most highly plasma protein bound of the NSAID group. Therefore, it poses a risk for drug displacement interactions with the multiple drug regimens in this age group. Due to the high propensity of CNS effects with indomethacin and the extremely long plasma half-life of piroxicam, using these medications as analgesics in the elderly is inappropriate.6,8,9
More often than not, the realm of podiatric surgery, either by the nature of the operation or the performance of multiple procedures, lends itself to the anticipation of moderate to severe pain. The podiatric surgeon should assume pain is present in an older adult who has undergone a potentially painful procedure. Accordingly, clinicians will need to choose a preemptive drug regimen equal to the task of alleviating this pain.
Opioids are the mainstay for treating moderately severe to severe postoperative pain in the geriatric age group.2 The commonly used pure agonists, such as morphine, hydromorphone, codeine, hydrocodone and oxycodone provide analgesia by stimulating the MU opioid receptor.10 When it comes to using pure agonists, they do offer distinct advantages in that they are short-acting agents (with a duration of three to four hours) and have no ceiling effect, which allows for dose titration.
One can simply initiate dosing in the elderly with standing orders of a short-acting, immediate release preparation, such as 10 to 30 mg of morphine on a regular schedule every four hours to achieve steady state plasma levels quickly as opposed to starting the agent prn and then converting to an extended release product to improve compliance. If one employs controlled release preparations to achieve steady state plasma levels, then clinicians would also need to institute rescue doses of a short acting opioid, comprising about 5 to 15 percent of the total 24-hour dose, as needed for breakthrough pain.11
Levorphanol and methadone are potentially useful for less frequent dosing. However, their longer duration of action creates the potential for drug accumulation and their risk for significant sedation makes them less than ideal for use in older adults. One should not consider fentanyl transdermal patches as a first line opioid due to erratic absorption from differences in body temperature as well as subcutaneous fat and water content in the elderly in comparison to younger individuals. The patch may be useful if the patient cannot take oral medication or there are impediments to other routes of administration. Nevertheless, one should ensure that the initial dose does not exceed 25 mcg/h and restrict the use of this patch to cognitively intact patients.2
Tramadol (Ultram) is a centrally acting hybrid analgesic with a dual mechanism of action. It exerts traditional agonist activity at the MU opiate receptor while providing adjunctive analgesia by inhibiting synaptic norepinephrine and serotonin reuptake. This agent appears to have a ceiling effect with titration limitations as well as a dose-dependent risk for seizures. Although tramadol could represent an alternative option, it is not a substitute for opioids when they are indicated.2,10
In the early 1990s, Beers, et. al., originally proposed guidelines that identified certain medications as inappropriate for use in elderly patients.9 Based on the Beers criteria, one should avoid the use of specific opioid analgesics, namely meperidine, propoxyphene and pentazocine.9,12
Meperidine is no longer considered an optimal analgesic for the treatment of moderate to severe pain. Not only does it have low oral bioavailability, the medication's potency in comparison to morphine is often overestimated with a short analgesic duration that rarely exceeds three hours, necessitating frequent intermittent administration. Frequent administration of meperidine even in recommended doses is associated with the accumulation of normeperidine, a neurotoxic metabolite that causes CNS effects and lowers the seizure threshold.13
Propoxyphene is a weak agonist that somehow has led to the misconception of prescribing it as a “mild” opioid. The analgesic efficacy of 65 mg propoxyphene HCl and 100 mg propoxyphene napsylate is equivalent to slightly less than 650 mg of acetaminophen or ASA. Keep in mind that propoxyphene is frequently dispensed in combination products with acetaminophen, which may actually account for most of its analgesic activity. Propoxyphene is also associated with norpropoxyphene, a CNS toxic metabolite that limits the medication’s usefulness in this age group.14
Pentazocine (Talwin) and butorphanol (Stadol) have mixed agonist-antagonist activity that block at the classic MU opiate receptor while predominantly stimulating at the kappa receptor. This group generally has reduced analgesic potency when one compares them to the pure agonists. They are non-titratable due to a ceiling effect and are associated with dysphoric CNS effects including visual and auditory hallucinations.10 Therefore, one should avoid using these agents in elderly patients.
Common opioid side effects include constipation, sedation, respiratory depression, nausea, vomiting and urinary retention. Constipation is extremely common and a particular concern for the elderly. One should ensure a continued prophylactic bowel regimen throughout the course of opioid treatment. This may include the use of a stool softener (docusate), adequate hydration and/or the use of a stimulant laxative (senna) to enhance colonic activity.15
Employing a multimodal approach can help reduce the opioid requirement by combining smaller doses of more than one agent to minimize the dose-limiting adverse effects of monotherapy. For instance, using an NSAID with an opioid would work at different sites along the pain pathway, resulting in improved analgesia with fewer opioid side effects.16
The elderly are more vulnerable to inadequate pain control so it is important to encourage them to take a more proactive role in their health care. The goal of safe and effective pain management ideally begins by counseling and advising the older patient prior to surgery on what to expect. Understanding the characteristics of the aforementioned common analgesics should hopefully provide insight for the podiatric surgeon in selecting an appropriate analgesic for this age group.
Dr. Juda is an Assistant Professor in the Department of Medicine at the Temple University School of Podiatric Medicine. He is in private practice in Christiana, Del.
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