Hazards of Hospitalization of the Elderly

Hospitalization is a major risk for older persons, particularly for the very old. For many, hospitalization is followed by an often irreversible decline in functional status and a change in quality and style of life [1]. A recent study showed that of 60 functionally independent individuals 75 years or older admitted to the hospital from their home for acute illness, 75% were no longer independent on discharge, including 15% who were discharged to nursing homes [2]. In many cases the decline cannot be attributed to the progression of the acute problem for which they are hospitalized. Even when the disease, such as pneumonia, is cured in a few days, or the hip fracture repair is technically perfect and uncomplicated, the patient may never return to the premorbid functional status. Between 30% and 60% of patients with hip fractures are discharged from the hospital to nursing homes; 20% to 30% of those persons still reside in nursing homes 1 year later [3-6]. Only 20% of one large group of patients returned to their preoperative functional level after repair of a hip fracture [7]. Some of the decline can be attributed to particular complications of the disease itself or to its management. Adverse drug reactions are an example of the latter. However, many elderly persons are susceptible to other complications not directly related to the illness or injury for which they were hospitalized or the specific treatment of the problem. Usual aging is associated with changes that increase susceptibility to various stresses. Some of these changes represent loss of reserve function and do not produce disability under ordinary circumstances. However, the elderly are vulnerable and stand at the threshold of functional disability, at risk of being projected over that threshold when stressed. Interaction of Aging and Hospitalization A number of explainable factors associated with hospitalization and bed rest, individually and collectively, thrust the elderly into disability. They are described in detail by Harper and Lyles [8], Hoenig and Rubenstein [1], and Mobily and Kelly [9]. These factors initiate a cascade of events (Figure 1) that frequently culminate in diminished quality of life. I outline some of the functional capacities that change with usual aging and that are further modified by hospitalization, along with the functional consequences of the interaction (Table 1). Table 1. Interaction of Aging and Hospitalization Muscle Strength and Aerobic Capacity Muscle mass and muscle strength are reduced with aging, which may reflect the progressive loss of reserve capacity associated with reduction of physical activity with age. Aerobic capacity is also progressively lost (maximum oxygen uptake, Vo 2 max), and research indicates that the loss is not cardiac in origin but the result of reduced peripheral use of oxygen related to the diminished muscle mass and strength as well as the capacity to respond to exercise [10]. Muscle contractions of certain minimal force and frequency are necessary to maintain strength. In the absence of any voluntary contraction, muscle strength decreases by 5% per day. Young men at bed rest lose muscle strength at the rate of 1.0% to 1.5% per day (10% per week) [11]. Inactivity rapidly contributes to muscle shortening and changes in periarticular and cartilaginous joint structure, which contribute to a tendency toward limitation of motion and contracture. The most rapid changes take place in the lower extremities [12]. Bed rest markedly diminishes aerobic capacity with substantial reductions in Vo 2 max values. For older persons who have diminished physiologic reserves but still can attend to their ambulation, toileting, bathing, and other daily functions, the accelerated loss of muscle strength and aerobic capacity after a few days of bed rest may result in future dependency in carrying out those activities. Even if reversible, long periods of rehabilitation will be required because reconditioning time is longer than deconditioning time [13]. Loss of muscle strength is also a major cause of falls in the elderly and may contribute to the many falls that occur in the hospital, particularly as the patients try to climb over the rails of the usual high hospital bed. Vasomotor Stability With increasing age, one of the most clinically important manifestations of alteration in autonomic function is baroreceptor insensitivity. The resultant tendency toward syncope is increased by the age-associated reduction in body water and plasma volume and may be further increased by disease-associated dehydration. Bed rest in the supine position results in loss of plasma volume averaging about 600 mL [14]. This loss contributes to the propensity for postural hypotension and syncope already associated with usual aging. Syncope under any circumstance can result in injury. The possibility of injury is increased if syncope occurs while getting out of a high hospital bed in a strange environment. Additional risk factors, described next, compound the consequences. Respiratory Function The mechanics of respiration are altered with aging. Costochondral calcification and reduction in muscle strength diminishes ribcage expansion. The residual capacity increases and occupies a greater proportion of total lung capacity [15]. The closing volume increases and greater numbers of dependent alveoli fail to ventilate as a result of airway closure [16]. The combination of effects on pulmonary ventilation reduces arterial oxygen tension (Po 2) so that a value of 70 to 75 mm Hg is not uncommon in a 75-year-old person. This reduction in arterial oxygen pressure produces little functional disability in a healthy elderly person. The supine position reduces ventilation even more by increasing the closing volume [17] enough to cause an additional fall in Po 2 of 8 mm Hg in a healthy elderly person. The further reduction in Po 2 may be sufficient to produce symptoms such as confusion in an elderly person at the threshold of pulmonary insufficiency. It may also contribute to the occurrence of syncope in persons already sensitized by vasomotor instability. Demineralization Involutional loss of bone mineral begins in early adulthood, is accelerated with the menopause, and varies in occurrence. Many elderly persons, particularly thin, white women, are osteoporotic and are at risk for fractures. It has been shown that vertebral bone loss accelerates to 50 times the involutional rate in healthy men on bed rest [18]. The loss incurred with 10 days bed rest required 4 months to restore. Some of the loss is due to lack of weight bearing, but the general negative nitrogen balance associated with immobilization probably contributes to the problem. The frequent falls that occur in hospitalized elderly, caused by factors already described, have increased the likelihood of fractures, particularly hip fractures. Urinary Incontinence With aging comes an increased tendency for urinary incontinence. Bladder capacity is reduced. In older men, prostatic hypertrophy is almost universal. Many women suffer relaxation of the pelvic floor and also vaginal atrophy. Uninhibited contractions of the detrusor muscle increase. However, only 5% to 15% of community-dwelling elderly persons are actually incontinent [19]. Others at risk are spared embarrassment by consciously and unconsciously developing strategies for toileting at appropriate times. Many hospitalized patients have difficulty implementing their habitual strategies to avoid incontinence. The environment is unfamiliar, and the path to the toilet may not be clear. The high bed may be intimidating; the bed rail, an absolute barrier; and the various tethers, such as intravenous lines, nasal oxygen lines, and catheters, become restraining harnesses. Psychotropic agents may reduce the perception of the need to void. About 40% to 50% of hospitalized persons over age 65 are incontinent [19], many within a day of hospitalization. The functional incontinence that occurs in the hospital explains the discrepancy between incontinence rates in community-dwelling and newly hospitalized patients. Skin Integrity With aging come changes in the skin: thinning of the epidermis and dermis, reduction in vascularity, decrease in epidermal turnover, and loss of subcutaneous fat. Direct pressure on the skin greater than the capillary perfusion pressure of 32 mm Hg for as little as 2 hours results in skin necrosis in anyone. After short periods of immobilization, sacral pressures reach 70 mm Hg, and the pressure under the unsupported heel averages 45 mm Hg. Unusual shearing forces result from movement in a jacked-up bed or wheelchair. Pressure sores occur frequently in hospitalized elderly patients usually developing within hours of immobilization. The rate may be accelerated in the case of the incontinent patient in a wet bed or chair. Sensory Continence An increased propensity to confusion with minimal provocation comes with aging. It can be partially explained by age-associated reduction in sensory input. Frequency of visual loss is increased as a result of presbyopia, cataract, and other eye problems. Hearing loss is variable but common. However, there are undoubtedly other factors related to the jumble of neurotransmitter, neurophysiologic, and neuroanatomic changes that are described in the literature and await explanation. Sensory deprivation or overstimulation results in confusion and delirium in normal people at any age if of sufficient intensity and duration. Twenty-nine percent of young persons placed in a simulated hospital room developed subjective sensory distortions after 2.5 hours [20]. The reduction of sensory input of all types that occurs with immobilization can produce intellectual and perceptual disorders [21]. It is not surprising that an elderly person, admitted to a hospital bed in a quiet room with subdued lighting, whose eyeglasses and hearing aid were left at home, suffers delirium. If the sensory deprivation al