GERIATRIC EMERGENCY MEDICINE

The Elder Patient - geriatric emergency medicine
Older patients represent a special population for emergency medicine. The approach that focuses on one chief complaint and develops a differential diagnosis based on life-threatening and common diseases may miss significant conditions in older persons. Older patients are more time-consuming, more difficult to evaluate, and use more resources than do younger adult patients.

The complexity of their presentations and dispositions, as well as communication problems with the patients, their families, and primary care providers, all make the ED evaluation of elderly persons more difficult as compared with younger adult patients. The physiology of aging results in altered disease presentations, altered pharmacodynamics, and decreased functional reserve, as well as social problems, which must be dealt with in the setting of a busy ED.

Epidemiology
The elderly population in the United States is growing rapidly, with projected increases from 200 percent for the 65- to 74-year-old segment, 300 percent for the 75- to 84-year-old segment, and more than 500 percent for those older than age 85 years by the year 2050. Approximately 12 percent of the population was 65 years of age or older in 1990, whereas 20 percent of the population (or 55 million persons) will be 65 years of age or older by the year 2030.

As noted, the oldest elderly, those age 85 years and older, are the most rapidly increasing segment of the elderly population. This is also the population with the most health problems and in greatest need for health care. There is great variability in the physiologic age of individual patients. A 55-year-old with multiple chronic diseases and poor physiologic reserve may have a physiologic age much older than a healthy 80-year-old.

In 1995, almost 16 percent of ED visits were made by patients age 65 years and older, and 46 percent were admitted to the hospital. Older patients spend more time in the ED, require more ancillary tests, and are more likely to be admitted to critical care units as compared to younger patients. The National Center for Health Statistics (NCHS) 2000 survey documents that persons aged 75 years and older had 64.8 ED visits per 100 persons per year, twice the rate for younger persons. The rate of ambulance use increased with age, with 43 percent of persons age 75 and older taking ambulance transport to the ED.

Pathophysiology
The basic principles of geriatric emergency medicine have been defined (Table 307-1). Older patients often present with ambiguous complaints, such as not feeling right, feeling weak, or not doing usual activities. Vague complaints, such as general weakness or functional decline, may indicate important diseases, such as sepsis, subdural hematoma, or myocardial infarction. Assessment of functional status can be used for classifying and evaluating these complaints.

Table 307-1 : Principles of Geriatric Emergency Medicine
1. The patient's presentation is frequently complex.
2. Common diseases present atypically in this age group.
3. The confounding effects of comorbid diseases must be considered.
4. Polypharmacy is common and may be a factor in presentation, diagnosis, and management.
5. Recognition of the possibility for cognitive impairment is important.
6. Some diagnostic tests may have different normal values.
7. The likelihood of decreased functional reserve must be anticipated.
8. Social support systems may not be adequate, and patients may need to rely on caregivers.
9. A knowledge of baseline functional status is essential for evaluating new complaints.
10. Health problems must be evaluated for associated psychosocial adjustment.
11. The emergency department encounter is an opportunity to assess important conditions in a patient's personal life.

Common diseases often present atypically in older persons, resulting in missed diagnoses unless physicians understand and suspect the atypical presentations in this population. For example, consider two common presenting complaints - chest pain and abdominal pain - and common diagnoses for each - myocardial infarction and acute appendicitis. Fewer than half of patients 85 years of age and older will present with chest pain as a symptom of acute myocardial infarction.

Instead, patients present atypically with dyspnea, syncope, weakness, or dizziness. Older patients with acute appendicitis are often diagnosed late and have a high perforation rate. A large percent of patients with appendicitis are diagnosed more than 48 h after the onset of symptoms, with up to 20 percent diagnosed after 3 days. The abdominal pain is vague, and the symptoms may be poorly localized. Classic patterns of pain and accompanying symptoms, such as nausea and vomiting, are present in only a minority of older patients with acute appendicitis. Older patients with acute abdominal conditions commonly lack physical findings of guarding or rebound.

Older patients frequently will have confounding comorbid diseases, and emergency physicians should evaluate whether the presenting complaint reflects an exacerbation of one of the comorbid diseases or a new disease process. Comorbid diseases, especially those treated with multiple medications, may also affect the management and disposition of patients.

Older adults take an average of more than four prescription drugs and more than two over-the-counter drugs each day. Approximately 30 percent of older persons will develop adverse medication effects, and they are twice as likely as younger adults to have adverse effects. Adverse medication effects account for approximately 5 percent of hospital admissions. The number of medications that a patient takes is directly related to the chance of adverse drug effects. Normal aging results in a loss of cardiac, pulmonary, hepatic, and renal functional reserve.

Thus, the margin of error decreases for many medications, such as nonsteroidal anti-inflammatory drugs. The distribution of drugs changes with age; as lean body mass decreases, the larger proportion of adipose tissue increases the volume of distribution of drugs, such as benzodiazepines, phenytoin, barbiturates, and phenothiazines, and prolongs their duration of action. Drug clearance depends primarily on hepatic and renal function. The decreased renal function with age may affect drugs such as digoxin and the aminoglycoside antibiotics.

Drug receptor interactions also play a role in pharmacodynamics. Older persons have an increased sensitivity to warfarin and benzodiazepines. Common complications of medications or drug interactions include delirium, depression, functional decline, worsening dementia, orthostatic hypotension, weakness, dizziness, falls, and incontinence. The impact of new medications prescribed in emergency departments, such as anticholinergics, sedatives, and diuretics, as well as adverse interactions with current medicines, should be anticipated.

Older persons frequently have cognitive impairment that may not be recognized by health care providers. Cognitive impairment includes both acute confusional states (delirium) and dementia. Abnormal cognitive states in older patients affect the reliability of the history and impact disposition planning. Acute cognitive impairment can be an important symptom of sepsis, congestive heart failure, metabolic abnormality, adverse drug effect, or subdural hematoma. When older ED patients are screened for cognitive impairment, 30 to 40 percent of those who have no previous history of impairment will have abnormal cognition based on formal mental status exams. Approximately 10 percent of patients will meet formal criteria for delirium, which should be considered a symptom of a medical emergency. Formal tools for evaluation of cognition are recommended later in this chapter.

Accurate laboratory test interpretation requires a knowledge of which "normal" values are altered with aging. Although many laboratories control for age variations in neonates and children, few list control values for older patients. For example, laboratory parameters such as the sedimentation rate, glucose and creatinine levels, and arterial blood oxygen tension change with physiologic aging.

The likelihood of decreased functional reserve should be anticipated in older persons. Most patients are asymptomatic until they are stressed or reach a critical threshold in which symptoms are manifested. Most organ functions decline with age. Resting cardiac output decreases at approximately 1 percent per year after age 30 years. Pulmonary, renal, neurologic, and immunologic functions also decrease with age. Chronologic and physiologic age, however, may vary considerably, depending on genetics, environment, health behaviors, diet, tobacco use, alcohol use, exercise, and stress. When older persons are stressed, for example, by extreme heat or cold, their regulatory mechanisms are not as effective as when they are not so stressed.

Older persons should be viewed in the context of their home environment and social support network. Simply addressing an injury or illness may not be adequate. More than 20 percent report a change in their ability to care for themselves following their ED visit. An independent-living 80-year-old woman who sprains her ankle may become incapacitated. Enlisting the help of a social service network and of home health providers will ensure that such patients are able to carry on the functions of daily living.

In addition, many older persons need to rely on caretakers, so an assessment of the caretaker's ability to help the patient is important. Is the caretaker an elderly spouse who will predictably injure himself or herself in trying to lift a patient who is incapacitated by a new injury? Elder abuse and neglect is a significant issue that should be assessed by questioning the patient and caretaker separately.

The emergency health care professional can play a key role in screening for such important conditions such as elder abuse, depression, alcoholism, malnutrition, incontinence, falls, and immunizations. In a multicenter study in which patients were screened, almost 80 percent of older patients demonstrated a problem in one or more of these areas.