Management of Pain in Special Populations of Cancer Patients
Management of Pain in Special Populations of Cancer Patients
Children, the elderly, AIDS patients, and former narcotic drug abusers pose special problems in pain management that may lead to undermedication even more frequently than occurs in the general population of cancer patients with pain. A multidisciplinary panel of six pain experts with clinical experience in caring for these special groups met in Santa Fe, New Mexico, to discuss assessment methods and pharmacologic approaches to the treatment of pain in these patients. A summary of the roundtable discussion follows.
C. Stratton Hill, MD: The literature continues to contain reports indicating that pain from advanced cancer is undermedicated. There also is ample evidence that, in some cases, pain may be difficult to manage. This roundtable discussion will explore some of the barriers to effective pain management and will outline practical approaches to difficult management issues that arise in special populations of cancer patients, such as children, the elderly, AIDS patients, and former narcotic drug abusers.
Some of the barriers to pain management are intrinsic to clinician-patient relationships, and others are extrinsic. In addition, there are many societal and cultural barriers to the adequate and appropriate use of opioids. These barriers are demonstrated by the fact that pain management does not become an issue until the intensity and diffuseness of pain require the use of systemic opioids. Alternatively, nonopioid methods of pain relief may be effective for a while but may be insufficient to manage severe pain.
In terms of cultural and societal barriers to adequate and appropriate use of opioids, much prejudice and misinformation exist among health-care professionals, patients, pharmacists, and friends and relatives of patients. Much of this bias comes from confusion about the legitimate and illegitimate uses of opioids.
Unfortunately, illegitimate images of opioid drugs often dominate our thinking. Physicians, who ultimately make prescribing decisions, often focus on customary and societally accepted uses of these drugs, rather than on their pharmacodynamic and pharmacokinetic properties. Some physicians are reluctant to prescribe opioid drugs for adequate periods of time because they generally prescribe these agents for the treatment of acute—not chronic—pain. They fail to recognize that, in instances of acute pain, opioid use is usually self-limited, whereas in chronic pain, it is necessary to use opioid drugs over a longer time period.
In addition, there is some reluctance on the part of clinicians to use stronger opioids, and the practice of polypharmacy to avoid their use is common.
The final barrier to adequate use of opioid drugs is fear of regulatory agencies. Drugs that are used for the treatment of pain are also drugs of abuse and are classified as controlled substances. Often, regulatory issues are so restrictive that clinicians may be reluctant to prescribe these drugs for legitimate medical purposes.
These issues should be kept in mind during our discussion of considerations for pain relief in special populations of cancer patients. Children will be the first such population to be discussed.
Ada G. Rogers, RN: For many years, conventional thinking held that children did not feel any pain because their nervous systems were not as developed as those of adults. This has been shown to be untrue, however.
Another major problem in pediatrics is the assessment of pain. In a younger child, pediatric nurses and physicians often rely on behavior as a means of assessing pain. Unfortunately, many clinicians assume that if children are engaged in “normal activities,” such as watching television, they are not in pain. In one study, however, I found that when asked about their pain, 50% of hospitalized children who were watching television, listening to music, or playing reported feeling severe pain. Thus, many children are undermedicated because behavior is used exclusively as the pain assessment tool.
For children over 3 year old, several more objective assessment tools available (Figure 1). In 1980, I developed a tool called “happy/sad faces,” which consists of a series of five faces with different expressions. It has proved to be useful in diagnosing pain in children from 2½ years old to approximately 8 years old. In children over age 8, one can use verbal rating scales (which ask the child to rate pain as slight, moderate, or severe) or visual analog scales. Children respond well to these assessment instruments.
With regard to selecting an analgesic for children, one problem is that very few good studies have been conducted in this population. The lack of clinical data is due to our reluctance to treat children with experimental drugs, as well to parental objections to the use of a placebo. Thus, we do not have a good understanding of what pain medications can and cannot do in children. Our current knowledge is based on clinical experience rather than research. It is only recently that some studies have been conducted in children, primarily using acetaminophen and ibuprofen.
Opioid analgesics are very well tolerated by children with cancer pain. The two most common concerns relate to the potential of the these drugs to produce respiratory depression and addiction. Both of these concerns are unfounded, as no data show that either of these side effects occurs in children with cancer pain.
Children can safely take morphine, hydromorphone, levorphanol (Levo-Dromoran), or methadone, among other opioids. However, I do not use meperidine chronically in pediatric patients. In children, as in adults, the accumulation of the toxic meperidine metabolite normeperidine can cause central nervous system excitation, ranging from irritability to grand mal seizures. Also, since children tend to develop itching more often than do adults, I generally use drugs that do not release histamine, such as oxy-codone, oxymorphone (Numorphan), and fentanyl (Tables 1 and 2).
Ronald Kanner, MD: Are the pediatric doses of opioids based on weight?
Ms. Rogers: Body weight is appropriate as a starting point, but once a child has been medicated, the clinician must observe the patient’s response and titrate the dose accordingly. If a child received analgesics in the past, previous dosing should be used as a starting point.
Dr. R. F. Kaiko at Memorial Sloan-Kettering Cancer Center studied almost 1,000 adult patients taking 8 or 16 mg of morphine. He found that age was a better parameter than weight for determining the starting dose. This guideline also applies to children. I have had young children taking very high doses of opioid analgesics who had no problems with breathing or sedation.
Christine Miaskowski, PhD, RN: What about the role of the parent or caregiver in managing pain? Are parents facilitory or obstructive? What are their fears?
Ms. Rogers: Concerns vary with from parent to parent. One of the biggest worries is drug abuse. Parents fear that the child—especially if an adolescent—will become addicted to pain medication.
Other parental fears stem from misinformation about what pain medications do in the body. Parents may think that these drugs will interfere with chemotherapy or deteriorate their child’s liver and lungs. Some nurses may perpetuate these misconceptions. For example, one nurse told a child that levorphanol would eat away his lungs if he kept taking it.
As to whether parents are facilitory or obstructive, I have found that once you win the confidence of a family member or caregiver, he or she may provide important information by monitoring and assessing the child’s pain.
Dr. Hill: Can children be trusted to administer intravenous patient-controlled analgesia (PCA)?
Ms. Rogers: Studies have shown that children 7 years and older can be taught to use a PCA system. However, PCA is not appropriate for every child. For example, a 14-year-old boy told me that he did not like pushing the button. He preferred to have his mother give him the injection of rescue medication. The main point that I wish to make about PCA is that it should not take the place of good pain assessment and management.