Special Population Considerations
There are important physiologic differences between children and adults that affect their response to pain medications. 98 Metabolism and clearance of drugs are different throughout infancy. Liver metabolism reaches full function by one month of age. Due to the relatively large liver compared to body mass, metabolism may be increased from ages two to six years. 99 Drug elimination is also affected by the difference in renal function. Renal blood flow, glomerular filtration rate, and tubular secretion are all reduced during the first year of life, after which renal function is similar to that of adults. 100, 101
Besides the differences in metabolism and elimination, the bioavailability of the drugs is different in children. Children have less body fat; therefore, water-soluble drugs are comparably more available in the plasma. Similarly, since lipophilic drugs are redistributed to the fat in lesser proportion, they are available in higher concentrations in the plasma and for a longer duration. 98 Drugs may affect the central nervous system in children more than in adults due to the fact that proportionately more of their cardiac output goes to the brain and more drugs and metabolites may cross the immature blood-brain barrier. 98
Decreased protein binding is another factor contributing to a higher bioavailability of drugs in children. Drugs affected by protein-binding include opioids and local anesthetics. 98, 100, 101
These differences are not just a review of second year physiology but are intended to alert the clinician as to why children need close monitoring when given medications. The dynamic changes in physiology throughout childhood make dosing difficult, even when following milligram per kilogram dosing formulas. In order to safely prescribe pain medications for children, drug references should be available for physicians to review, and patients should be carefully monitored for both therapeutic benefit and undesired side effects. 102
For over a decade, the National Hospital Ambulatory Medical Care Survey has tracked ED visits and the demographics of patients presenting to them. Patients over the age of seventy-five consistently have the highest number of visits, even as the overall population has grown in ED utilization. Visits from nursing home facility patients also continue to rise. 103-107 Social issues may contribute to elderly patients hoosing the ED for care. Reasons include the fact that they tend to have lower incomes, live alone, may be less educated, and have difficulty accessing care by other avenues. 108 All of these factors complicate the issues of pain management in the elderly population.
Pain is a common problem affecting the elderly population. It has been estimated that 50% of independent living senior citizens experience chronic pain and that 45 to 80% of patients living in longterm care facilities have pain. 109 The elderly present to the ED with more conditions of high or immediate urgency, compared to younger patients. 110 The elderly presenting to the ED have, not surprisingly, more co-morbid diseases 108 and presumably more complex daily medical regimens. The addition of new medications in the ED makes for greater medical complexity for older adults. This has had a negative effect on patients understanding their medications. Pain medications were the second most commonly added medication, after antibiotics. 111
Elderly patients with a personal physician and those with health insurance of any kind, have a lower risk of severe pain; elderly patients who selfinitiate treatment of their health problems have a lower risk of frequent pain. 112 Conversely, those patients without a regular physician, without health insurance, and those relying on the physician for direction have been reported to be at risk for frequent or severe pain.
The American Geriatric Society has made several recommendations for the management of pain in elderly patients. They have recommended acetaminophen as the drug of choice for mild to moderate pain and opioids for moderate to severe pain.
Acetaminophen has been used with satisfactory pain relief and has a lower side effect profile than nonsteroidal anti-inflammatory drugs (NSAIDs). 113, 114
Chronic Pain and Drug Seekers
Many EPs consider the management of pain in certain patients to be one of the more trying aspects of clinical practice. Different physicians may experience this frustration in different subsets of patients, but frequently it includes patients who have chronic pain, those who are thought to be drug-seeking, and those who choose the ED as their venue of choice to have their pain treated. There are various characteristics to the practice of emergency medicine that make it vulnerable to abuse by patients: Anonymity of patients, difficult access to medical records, multiple EDs within a given city, and an obligation to see and stabilize anyone complaining of pain.
Opiate-dependent patients are also a challenging population to care for. Because of their dependence, the patient may have a different response to painful conditions and may require higher doses of medication than physicians are accustomed to using. Suspicion of these patients may lead to a failure to diagnose significant conditions (e.g., epidural abscesses or necrotizing fasciitis), making management especially challenging. Confounding the care for these patients, is the high incidence of concurrent psychiatric disease; indeed, one study reported that patients with opioid-treated chronic pain and concurrent psychiatric disease have a 32% incidence of substance abuse. 115 Intervention with a multidisciplinary team can improve pain scores and facilitate a comprehensive management stategy; however, this approach if often not feasible in a busy ED. 115
Pain management has become an active issue in health care policy over the last decade. The Pain Relief Promotion Act of 2000 was drafted by the House of Representatives. There are two titles within this act: Title I, "Promoting Pain Management and Palliative Care" which amends the Public Health Service Act to require the director of the Agency for Healthcare Research and Quality to promote and advance scientific understanding of, and collect and disseminate protocols and evidencebased practices regarding pain management and palliative care authorizes the Secretary of Health and Human Services to award grants, cooperative agreements, and contracts for the development and implementation of programs to provide education and training to health care professionals in pain management and palliative care." Title II: "Use of Controlled Substances Consistent With the Controlled Substances Act" which amends the Controlled Substances Act to declare that, for that Act and any implementing regulations, alleviating pain or discomfort in the usual course of professional practice is a legitimate medical purpose for the dispensing, distributing, or administering of a controlled substance that is consistent with public health and safety, even if it may increase the risk of death." 116
More recently, the National Pain Care Policy Act of 2005 was introduced in the House of Representatives to "Declare adequate pain care research, education, and treatment as national public health priorities and for other purposes." One of the goals is to establish within the NIH a National Center for Pain and Palliative Care Research. While both of these acts are still in committee, their existence highlights the recognition that pain management is an area in need of improvement that can only occur through research and education. 117
Regulations, acts, and laws have significant impact on the practice of medicine. The federal government does not directly control the practice of medicine;this is done by the states. However, the federal government does directly regulate controlled substances through other means. The Drug Enforcement Agency empowered by the Controlled Substances Act from 1970 is primarily concerned with the illicit use and diversion of controlled substances. 118 The federal government also influences the practice of medicine indirectly through various agencies and laws, such as the Joint Commission on Accreditation of Healthcare Organization (JCAHO) standards and the enactment of Emergency Medical Treatment and Labor Act (EMTALA), both of which address issues of pain.
The direct control of the practice of medicine is done by the states. It is important for physicians to be aware of their own state regulations and statutes, which differ with regards to the balance between admonition to providers to relieve pain and obligation through controlled substance legislation.
The pain relief act of 1996, which encouraged the necessary use of opioids for the management of pain, did not actually set regulations for the practice of medicine. It was intended to serve as a model for state legislators to follow. Many states have followed suit and have passed pain relief legislation that follows the model of the federal act. Generally, the various state acts encourage the use of pain management guidelines. The guidelines are not meant to serve as standards of care, but to protect physicians and other providers from prosecution when following the guidelines. 118 However, this protection has only been minimally addressed in the courts. A few recent cases have treated pain management as an obligation by the provider. One family successfully sued a nurse and a nursing home who withheld pain medication from a terminally ill patient for fear that he would become addicted. 119
JCAHO has been committed to the improvement of pain management for some time. In 1999, they mandated that hospitals treat pain as the "fifth vital sign." 120 In 2001, they issued new standards requiring assessment and control of pain. These standards do not tell institutions how to manage pain, but require that a pain policy be in place and that pain assessment occur. They recommended that pain be assessed on initial contact, when care is transferred from one setting or provider to another, after any intervention, at regular intervals, and immediately before discharge. 121 Additionally, they recommend the use of a pain scale appropriate to the patient population being treated.
In 2002, JCAHO teamed with the American Medical Association (AMA) and National Committee for Quality Assurance (NCQA) to "Develop a common set of evidence-based measures for evaluating the appropriateness and effectiveness of pain management." Through convening an expert panel of pain management experts, their goal was to help health care institutions and practitioners determine how well they are managing individual's pain. 122
Moreover, effective pain management has become a priority for our specialty. The American College of Emergency Physicians (ACEP) issued a policy statement in 2004. 123 (Figure 1,) Additionally, ACEP has established a clinical policy for the use of narcotic analgesia in patients with abdominal pain.124 While there is no specific guideline, they offer the option of providing narcotics to patients in the ED with abdominal pain. This topic is discussed further in the section on "Controversies in Pain Management."