[General]
Geriatric medicine (Geriatrics): An interdisciplinary approach to management of sickness and disability and to health promotion and disease prevention in the elderly that involves gerontology (the study of changes of normal aging as differentiated from disease effects).
Most age-related biologic functions peak at < 30 yr of age and may gradually decline in a linear fashion (see Table 293-1); although this later decline may be critical during stress, it has no effect on daily activity. Thus, disease, rather than normal aging, is the prime determinant of functional loss in old age.
Many decrements reportedly caused by aging are often attributable to lifestyle, behavior, diet, or environment, which can be modified. For example, aerobic exercise can partially reverse declines in 
o2 max, muscle strength, and glucose tolerance in healthy but sedentary older persons. The effects of aging may be less dramatic than thought, and healthier, more vigorous aging may be possible for many persons.
Cross-sectional studies comparing persons of different ages are relatively easy to do but may be less useful than longitudinal studies comparing persons over time to their younger selves. Such studies are difficult because of the long duration and high dropout rate; also, it is hard to find healthy aging subjects.
Demographics: At the turn of the century, persons > 65 yr accounted for 4% of the U.S. population; currently, they account for > 12% (33 million, with a net gain of > 1000/day). It is estimated that in 2030, when post-World War II baby boomers reach age 80, > 70 million Americans (> 20%) will be aged > 65 yr, and the increase in the percentage of persons aged > 85 yr will be greater.
Life expectancy: At age 65 yr, a man has a 13-yr life expectancy but at age 75 yr still has a 9-yr life expectancy. At age 65 yr, a woman has a 20-yr life expectancy but at age 75 yr still has a 12-yr life expectancy. Overall, women live about 8 yr longer than men, probably the result of genetic, biologic, and environmental factors; thus, there are more elderly women than men. Survival differences have not decreased, despite women smoking more and moving into traditionally male job markets. The maximum human life span (estimated at 110 to 120 yr) has increased modestly compared with the major increase in average life expectancy during this century, but increases continue. Persons aged > 65 yr are in better health than their predecessors. However, with all cohorts, the oldest old decline most.
Disorders Common Only In The Elderly
Some disorders occur almost exclusively in the elderly (see below and Ch. 215 [Urinary Incontinence]), and some occur in all ages but are far more common in the elderly (see Table 293-2). Such disorders often coexist in the elderly.
MULTIPLE DISORDERS
Older persons have qualitatively different health care needs. An average of six diseases coexist in older persons, although a primary physician may be unaware of 1/2 of them. Disease in one organ system weakens another system, compounding deterioration of both, leading to infirmity, dependence, and, if uninterrupted, death. Burdens of multiple disorders are complicated by social disadvantage, emotional vulnerability, and poverty (as patients outlive their resources and supportive peers).
Active case-finding surveillance mechanisms are necessary because multiple disorders in the elderly complicate diagnosis and treatment. History, physical examination, and simple laboratory tests help screen for common, treatable conditions (eg, B12-deficiency or iron-deficiency anemia, heart failure, GI bleeding, uncontrolled diabetes mellitus, active TB, foot disease interfering with mobility, oral disorders interfering with eating, correctable hearing and vision defects, dementia, depression), which often go undiagnosed in the elderly. Frequent review of prescription and OTC drug use is important. Early detection allows for early intervention, which can prevent deterioration and improve quality of life through relatively minor and inexpensive maneuvers.
Caring for an elderly person with multiple disorders demands high diagnostic, analytic, synthetic, and interpersonal skills. Often, the clinician's familiarity with the patient's behavior and history (including mental status) underlies early recognition of a disorder and allows interventions that may involve lifestyle adjustments. Commonly, the first signs of physical illness, often at a treatable stage, are mental or emotional, tending to confirm the stereotype of "senility" and deterring proper diagnosis and treatment if casually accepted.
When multiple disorders coexist, bed rest, surgery, drugs, and other treatments may be disastrous if not well integrated and scrupulously monitored. Bed rest alone is a cause of morbidity in the elderly: complete bed rest leads to a 5 to 6% loss of muscle mass and strength per day. Treating one disorder without treating associated ones may accelerate decline.
NORMAL-PRESSURE HYDROCEPHALUS
Cerebral ventricular dilation with normal lumbar CSF pressure, producing dementia, apraxia of gait, and urinary incontinence.
Normal-pressure hydrocephalus (NPH) is a rare cause of dementia in the elderly (see also Non-Alzheimer's Dementias in Ch. 171). It may be caused by previous surface inflammation of the brain, usually from subarachnoid hemorrhage or diffuse meningitis that presumably results in scarring of the arachnoid villi over the brain convexities where CSF absorption usually occurs. Supporting data are meager, however, and elderly NPH patients rarely have a history of predisposing disease.
Symptoms and Signs
NPH classically consists of dementia, apraxia of gait, and incontinence, but many patients with these symptoms do not have NPH. Typically, motor weakness and staggering are absent, but initiation of gait is hesitant--described as a "slipping clutch" or "feet stuck to the floor" gait--and walking eventually occurs. Other gaits have been described. NPH has also been associated with various psychiatric manifestations that are not distinctive. NPH should be considered in the differential diagnosis of any new psychiatric illness in old age.
Diagnosis and Treatment
CT or MRI and a lumbar puncture are necessary for diagnosis. On CT or MRI, the ventricles are dilated; CSF pressure is normal. Brief improvement after removing about 50 mL of CSF indicates a better prognosis with shunting. Radiographic or pressure measurements alone do not seem to predict response to shunting.
Shunting CSF from the dilated ventricles sometimes results in clinical improvement, but the longer the disease has been present, the less likely shunting will be curative.
ACCIDENTAL HYPOTHERMIA
Fall of body temperature to < 35° C (< 95° F).
(See also Ch. 280.)
Accidental hypothermia in the elderly is probably common in the winter. In Great Britain, thousands of elderly die each year from accidental hypothermia; however, one U.S. study did not find lowered temperature among high-risk community-dwelling elderly in Maine during the winter. The wide range of estimates can be explained by the fact that death cannot confidently be attributed to accidental hypothermia postmortem because most dead persons are cold. If data from Great Britain are extrapolated to the U.S. population, nearly 50,000 elderly Americans may be hospitalized each winter with occult hypothermia.
Etiology and Pathogenesis
Elderly persons with borderline hypothermia have age-related autonomic defects producing low peripheral resting blood flow, a nonconstrictive vasomotor response to cold, and easily provoked orthostatic hypotension. These defects are exacerbated by phenothiazines and correlate with hypothermia risk.
The provocative stressor does not have to be prolonged exposure to severe cold; although most episodes are initiated by temperatures < 18.3° C (< 65° F), elderly patients may become hypothermic in homes as warm as 18.3° C. Besides inadequate environmental heating in the winter, contributory factors include diminished perception of cold and poor heat conservation mechanisms. Predisposing factors include various drugs (eg, antipsychotics, sedatives and hypnotics, tranquilizers, alcohol), heart failure, hypothyroidism, hypopituitarism, uremia, Addison's disease, starvation, ketoacidosis, pulmonary infection or other sepsis, brain injury, and any immobilizing illness.
Accidental hypothermia develops over many hours to several days. Body temperature < 35° C (< 95° F) continues to fall slowly and insidiously, terminating in death if the environment is unaltered. The overall mortality rate is about 50%, but survival is largely determined by the presence and severity of complicating disease.
Symptoms and Signs
Patients are at high risk for death and for a clinical syndrome mimicking stroke or metabolic derangement. As body temperature drops, fatigue, weakness, incoordination, apathy, and drowsiness lead to acute confusion that progresses to stupor and coma when body temperature falls to < 32.2° C (< 90° F). Hallucinations, combativeness, and resistance to aid may occur. Hypothermic patients have hands, feet, and abdomen that are cold to the touch. Shivering is strikingly absent, respirations are shallow and infrequent, slow pulse and low BP with atrial and ventricular arrhythmias are common, and the face may be puffy and pink. In slightly < 50% of hypothermic patients, ECG may show a characteristic J wave early--a small positive deflection following the QRS complex in the left ventricular leads. More commonly, ECG shows baseline oscillation produced by a fine rapid muscle tremor that is often mistaken for electrical interference or voluntary motion. This fine tremor is usually not grossly apparent. It is probably the elderly hypothermic patient's physiologic equivalent of shivering. Neurologic signs of tremor, ataxia, pathologic and depressed reflexes, coma, seizures, and a marked increase in muscle tone may occur. If temperature fall is uninterrupted, death due to cardiac standstill or ventricular fibrillation usually occurs between 29.4 and 23.9° C (85 and 75° F).
General metabolic effects of hypoxia and tissue necrosis are the rule, although if the patient survives, low temperature may delay the onset of many complications (most commonly, pancreatitis, pulmonary edema, pneumonia, metabolic acidosis, renal failure, and gangrene of the extremities).
Diagnosis
Concern and vigilance are necessary for diagnosis. A high index of suspicion is essential. Health care personnel must look for low body temperature in the elderly, because usually only normal or elevated temperatures are documented during patient evaluation. The standard clinical thermometer reads 34.4 to 42.2° C (94 to 108° F) and is rarely shaken down to < 35.6° C (< 96° F); electronic thermometer readings may be unreliable with temperatures < 34.4° C. A low-reading thermometer, registering 28.9 to 42.2° C (84 to 108° F), is available and should be used when hypothermia is possible.
Treatment
Body temperature should be increased to normal slowly (<= 0.6° C [<= 1° F]/h). More rapid rewarming has often resulted in irreversible hypotension. Heat conservation is achieved with blankets or more sophisticated insulating materials in a warm room. Close monitoring and anticipation of common complications are essential to successful treatment.
