How To Manage Surgical Pain In Elderly Patients
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.