The Aging Process

Aging is a natural consequence of life. It leads to anatomic, biochemical, and physiologic alterations in every organ system (Table 101-1). Common degenerative disorders and diseases include atherosclerotic and cerebrovascular disease; chronic obstructive pulmonary disease; emphysema; diabetes mellitus; arthritis; emotional, mood, and memory disorders (e.g., depression, Alzheimer’s disease); and impaired thermoregulation. Polypharmacy (including excesses in medication intake) is a problem. Accidents due to unsteadiness, falls, forgetfulness, and operating machinery and vehicles take their toll. The cumulative effect of these changes on elders subjected to stressful environments produces a major increase in health risk and health care demand.^4,15

Anatomic changes are organ specific, because organs appear to age independently and not necessarily in parallel fashion. Furthermore, laboratory tests must be carefully interpreted. For example, glomerular filtration rate (GFR) and renal blood flow (RBF) decrease with age, but many elders have normal serum creatinine levels because there is a concomitant loss of muscle mass due to aging and, as a result, lower creatinine production. Physical and physiologic alterations may occur slowly. They may not be apparent for many years, yet result in “silent” functional and anatomic changes.

The degree of loss of function in various physiologic systems can be approximated by using the “1% rule,” which states that “most organ systems lose function at roughly 1% per year after the age of 30 years.”³⁰ Some age-related biologic changes and their resulting functional changes are listed in Table 101-1.

Inasmuch as aging reflects the effects of the passage of time, injuries and illnesses that occur along the path of life may produce cumulative anatomic scars, which, when combined with the degenerative changes of aging, may result in a functionally impaired older adult. The risk may be greatly exaggerated by wilderness ventures. The challenge to health professionals is to determine the extent of that risk and take appropriate action.

Etiology of the Aging Process

Some individuals age faster than others. Lifestyle and genetic predisposition are the most commonly incriminated “causes,” but this does not explain the biologic basis for aging.²⁵ Genetic events may somehow determine longevity. For example, there is an increased risk for development of Alzheimer’s disease in the presence of an allele of apolipoprotein E (ApoE) gene, which encodes a carrier of cholesterol.² Selman and colleagues have proposed that deletion of ribosomal S6 protein kinase 1 (S6K1) leads to an extended life span and resistance to age-related processes in mice.⁴⁴ Nevertheless, support for genetic determination of tissue longevity is scant. Most researchers believe that the processes of aging are multifactorial. Speculative theories suggest that damage to deoxyribonucleic acid (DNA) and proteins occurs from a variety of sources, such as reactive oxygen species, including superoxide, the hydroxyl radical, and hydrogen peroxide. According to Hoeijmakers, damage to DNA has implications both for cancer and acceleration of the aging process.²⁶

Hayflick observed that each body cell undergoes a finite number of divisions, roughly 50, after which the cell dies.²⁵ This number of divisions is known as the “Hayflick limit.” Each cell replication has a span of about 18 months and may be a predictor of individual human longevity. For example, with a cellular life span of 18 months, 50 doublings would result in a human life span of 75 years. Variation in the duration of each doubling has been speculated to be a predictor of length of life.

The Hayflick limit is a function of caps, called telomeres, at each end of the chromosomes. Each cap is a DNA-protein complex, which shortens after each cell division, protected by a cellular enzyme, telomerase. Eventually, after about 50 divisions, the telomeres become too short for further division and the cell dies.

Molecular concomitants of aging include alteration in chromosomal structure, mitochondrial deterioration, DNA cross-linking and single strand breaks, decline in DNA methylation, and loss of telomeric sequencing.

Other theories on the aging process include cellular changes, autoimmune mechanisms, neuroendocrine factors, and even a “biological clock,” but Strehler⁴⁴ feels that the cause should explain the progressive deleterious and intrinsic changes universal within the species. For example, some animals, usually cold-blooded fish or amphibians, which may grow to an indeterminate size, may also have an indeterminate life span, whereas warm-blooded animals with a limited or fixed size after maturation may die at a more predictable time and at an actuarially determined rate.⁴⁵

Questions concerning the nature and cause of aging include the following:

In perhaps the clearest summation of these theories, Hayflick suggests that the ultimate effect from the many factors influencing and affecting human life is that we simply exceed our reserve capacity. This lends support to the mountaineering dictum, “Always keep your reserve,” which is particularly appropriate for elders.

Definition of Elders

Why Some Elders Venture Into the Wilderness

Hard work, family and fiscal responsibilities, and delayed gratification are characteristics of Western industrialized cultures. As retirement years approach and leisure time increases, seniors begin to increase their participation in recreational and outdoor activities.

The U.S. National Park System studied the frequency of recreational activities in the National Parks from 1982 to 1983 and found, in order of frequency, the following activities: driving for pleasure, sightseeing, walking for pleasure, picnicking, stream/lake/pool swimming, and motor boating.⁹

A repeat survey, completed by the National Park Service in 1994, found that walking has become the most popular single outdoor activity and now involves over 134 million participants. Walking is especially attractive for an older person because it is healthful, self-paced, and socially rewarding when enjoyed with others. With population increases of persons age 70 and older, predictions indicate that many new trails and walking venues will be needed. The most striking change in activities is the dramatic increase in bird watching, having risen from 21 million in 1982 to 54 million in 1994, an increase of 155%. Growth in participation within other activities includes hiking (94%), backpacking (73%), downhill skiing (59%), and primitive area camping (58%).¹⁰

Nash concluded that the personal reasons for elders to venture into the wilderness are for enjoyment of nature, physical fitness, tension reduction, tranquility and solitude away from noise and crowds, experiences with friends, enhancement of skill and competency, and excitement or even the thrill of risk-taking³⁶ (Figure 101-2, online). Some ventures, however, such as off-road motorcycling, kayaking, and cross-country skiing, take place in difficult and inaccessible areas under extraordinary environmental circumstances (cold, altitude, rough terrain). If an emergency occurs in such locations and circumstances, search and rescue services or medical intervention may be required.

FIGURE 101-2 President George H. W. Bush lives up to his remark, “Even old guys can still do stuff!,” on his 75th and 80th birthday parachute jumps.

(From Perspectives, Newsweek, June 21, 1999. Courtesy George Bush Presidential Library.)

Physical Activities of Elders in the Wilderness

For elders, the physical and environmental demands of certain activities may be excessive. The physical workload of a wilderness venture depends on its nature and the characteristics of its component parts. For example, is the venture a walk or a climb? What is the nature of the terrain? What is the altitude? What is the ambient temperature? It is prudent for elders to examine plans for prospective wilderness ventures and to select activities consistent with their personal capacity, skill, and tolerance.

Wilderness activities can be classified according to their physical, technical, and environmental characteristics. The skill, judgment, and capacity of all participants, elders included, can be matched with the characteristics of the venture to determine whether individual capacity is adequate for the demands.

Classifying Wilderness Ventures

One classification scheme for wilderness ventures ranges from those that are extremely demanding and risky undertakings to those with minimal physical and environmental requirements (see Table 101-2). Although this classification is very general, it can be helpful in examining prospective participants and matching demands of the wilderness task or activity facing that individual.^12,14

Physiologic Workload of Wilderness Activities

Workload of wilderness ventures and functional capacity of individuals can be defined with a degree of precision by using measurements of energy demands from indirect calorimetry derived from oxygen consumption techniques. Oxygen consumption may be expressed as , calories (1000 cal = 1 Kcal or 1 C [Cal]) or as metabolic equivalents (METs).

The term MET, considered to be the energy cost of sitting, is defined by convention as 3.5 mL oxygen per kilogram of body weight per minute. Multiples of the MET are used to define the energy cost of various activities. For example, walking 2 miles an hour on a level, smooth surface requires 7 to 9 mL O₂/kg/min or approximately 2 METs; 3 miles an hour requires 10.5 mL O₂/kg/min or 3 METs, and so on. Lists of the energy cost of various activities given in calories or METs are available. Most activities of daily living (ADLs) require an energy expenditure of less than 3 METs. When a task is complex, there may be several levels of energy cost of various components.

Armed with the energy cost of a planned activity, a venture planner can proceed with a comparison of the task requirements and the functional capacity of the participant. The average 40-year-old man in this country can reach a 10-MET activity at the point of exhaustion, the PWCmax. Derived from this is a useful scale of 1 to 10; that is, 1 MET is the energy cost of sitting, increasing to 10 METs as the PWCmax of the average 40-year-old man. Tolerance to physical activity among women, increasing for several decades, is now within 1 to 2 METs of that of men. Well-conditioned athletes can reach a PWCmax of around 13 to 23 METs.

A natural decline in PWCmax occurs with age and results in a loss of roughly 1 MET of PWCmax per decade after 40 years of age. The average maximal functional capacity of a healthy 70-year-old man is approximately 7 METs.

It has been empirically observed that a healthy individual can function at an energy expenditure of about 25% to 40% of personal PWCmax over an 8-hour period of time without being too exhausted to get up the next morning and repeat that level of energy expenditure. A healthy person with a 10-MET PWCmax should be able to handle roughly a 3-MET activity for 8 hours.

These figures are very general approximations only, and the circumstances of each prospective venturer need to be considered individually. Of course, skill and experience with any activity are the best predictors of a safe and successful venture.

Classification of Individuals Considering Wilderness Ventures

Two basic physiologic factors affect the physical relationship between the venture and the participant: (1) the physical workload of the activity and (2) the capacity of the individual to tolerate the physical workload as influenced by the environmental stressors. Physical demands of the venture were classified previously. A similar classification assists in matching the participant with the venture (Table 101-3). The populations presenting to the physician may fit the distribution curve shown in Figure 101-3, where the groups defined in Table 101-3 are graphed. These classifications serve as starting places for more precise recommendations for the individual presenting to the physician for advice concerning physiologic capacity to tolerate the physical demands of a specific adventure.^12,14,15

TABLE 101-3 Classification of Participants in Wilderness Ventures

FIGURE 101-3 Classifying prospective participants according to physical characteristics, functional capacity, and experience helps match the candidate with demands of the venture. Here, prospective participants are arranged with an idealized representation of participants divided by standard deviations according to the classifications in Table 101-3.

Matching Individuals With Wilderness Physical Activities

Individuals who plan to participate in wilderness ventures probably have already been through a form of natural selection. For example, a person who aspires to participate in an expedition to Mt Everest will in all likelihood have already participated in a similar activity and will have proved his or her capacity to function at an extreme level of performance. This person would most likely be in participant group A or B. An individual who is healthy but has not recently been involved in vigorous activities and has become “deconditioned” may be in group C. The motivation may be a desire to reaffirm youth or vigor in some form of exciting or hazardous activity. These individuals deserve the scrutiny of alert organizers with, perhaps, an assessment before the venture in order to consider risk factors or occult health problems.

Particular attention should be directed toward any individual at risk of illness or injury (group D), even though manifesting evidence of disease may not be superficially apparent. For example, cardiovascular risk factors, such as smoking, a fat-laden diet, and high blood pressure, may warrant detailed medical examination to determine level of functional capacity considered safe for that individual. An examination may even disclose the presence of diseases, asymptomatic or symptomatic.

Group E includes persons with definite manifestations of illness. Supervised outdoor activities can still be of value in such cases and have even been used as a form of physical therapy and rehabilitation for persons with various illnesses, including cardiovascular disease. Persons in this category should be individualized in their assessment and require a high degree of medical evaluation and supervision.

Physical Conditioning to Prepare Elders for Wilderness Ventures

Elders considering wilderness activities should consider the appropriateness of their participation in a contemplated venture. After a medical and functional examination, the classification may suggest the need for a physical conditioning program to increase individual reserve capacity. An individual can tolerate an energy cost of approximately one-fourth to one-third of his or her maximal physical work capacity over a period of 8 hours. If the demands of a venture exceed predicted tolerance, PWCmax can be enhanced by 15% or more by a 3- to 6-month graduated conditioning program. A conditioning program should begin with a warm-up session that includes flexion and extension exercises, followed by a cardiovascular conditioning component and a cool-down component. The aerobic component should last at least 20 minutes at a level of about 50% of individual PWCmax. Some persons can learn to monitor the pulse rate corresponding to this level of activity as a monitoring technique. Mouth breathing, which usually occurs at about 60% of maximal work capacity, is also a useful body signal for marking the intensity of the activity. As intensity increases, catecholamines increase. Above 70% of maximal work capacity, the catecholamine level may be hazardous for an individual with subtle cardiovascular disease. Consequently, if the subject keeps the intensity of the activity below that requiring mouth breathing, the aerobic activity should be in the range below 60% of the individual maximal capacity, a relatively safe range in healthy individuals. This level of conditioning is helpful and may be reasonably safe for seniors, although not at the level necessary for conditioning competitive athletes. If cardiovascular disease is present, a conditioning program should be individualized and supervised. A structured program is an ideal time for teaching an individual to read his or her personal body signals, a collection of markers for physiologic responses to activity (Box 101-1).

The American College of Sports Medicine has developed a position paper on exercise and physical activity for older adults. This should be reviewed by any serious student of the subject.¹ Recommendations include endurance training to help maintain and improve cardiovascular function and strength training to help offset loss of muscle mass. Standards for exercise programs for subjects with cardiovascular disease have been available from the American Heart Association since 1979.¹⁷ Additional benefits from regular exercise include improved bone health, reduction of risk from osteoporosis, improved postural stability, and increased flexibility and range of motion. Psychological benefits include a feeling of well-being, relief of symptoms of depression often associated with older adults, and a general joie de vivre.

Environmental Stresses and Elders

Environmental variables encountered in the great diversity of outdoor wilderness activities may produce significant physiologic stresses. These variables include extremes of heat and cold, high altitude, water immersion, tropical humidity, desert aridity, and ultraviolet exposure. The common denominator in nearly all wilderness ventures is physical activity, often at extreme levels. To compound the complexity of physical activity influenced by environmental stress, the physician may have to care for a senior afflicted with subclinical or manifesting disease. When the physiologic demands from environmental stresses are added to the increased and prevalent degenerative conditions and diseases associated with aging, risk for illness and injury is multiplied. The complete package of age, conditioning, environment, nature of the activity, and experience must be considered when an elder is advised or treated in the wilderness.

Clinical Medicine in Elders

Wilderness medicine is in part defined as traditional medicine in nontraditional settings. The principles of risk, pathophysiology, and treatment of health problems are those of the established medical community. However, characteristics of the acute situation, setting, and environmental conditions affect care, search and rescue, transportation, and medical support. When older age is a factor, an additional set of concerns is added, including reduction in physical reserve, increase in rate of physical deterioration during exercise, and reduction in margin of safety. Enhanced skills of analysis, planning, intervention, and action are demanded of the rescuers and medical team.

There are two important occasions when wilderness medical leaders should consider health/medical evaluation for older venturers: (1) during the planning phase before the venture and (2) following symptoms that may occur during or after the venture. Components of the pretrip evaluation are based on the characteristics of the individual and on the nature of the proposed venture. These are discussed later (see Medical Examination). Evaluation after the onset of symptoms or for intervention requires clinical judgment dictated by the specific problem or symptom and is considered in discussions of specific illnesses.

Cardiovascular Disease

Age-related changes in the cardiovascular system affect heart rhythm, myocardial pump function, and afterload. With aging, there is progressive reduction in the number of pacemaker cells in the sinoatrial (SA) node, increase in myocyte cell volume per nucleus in both ventricles, increase in peripheral vascular resistance, and increase in aortic impedance from loss of elasticity. Increased levels of circulating catecholamines are associated with aging, especially with stress, but β-adrenergic–induced vasodilation decreases with age. This is important for exercise tolerance in elders.

Cardiac rhythm disturbances range from the nuisance effect of premature systoles to significant rhythm disturbances, such as atrial fibrillation, to potentially life-threatening ventricular arrhythmias. An elder who is aware of symptoms related to an arrhythmia should seek evaluation by a physician before a wilderness venture. The evaluation should include history of onset of symptoms and initiating factors, medications taken, physical examination with emphasis on auscultation of the mitral and aortic valves, electrocardiogram, ambulatory monitoring if there is a history of heart disease or lightheadedness, and possibly an echocardiogram.

Valvular changes, especially of the aortic and mitral valves, may be recognized by auscultation and confirmed by echocardiography, and perhaps by cardiac catheterization. The subject with a prosthetic cardiac valve may be at risk during prolonged ventures with exposure to inclement weather, infectious diseases among fellow venturers, or diseases among the local populace.

The presence of pump failure, either systolic or diastolic, may be indicated by recent weight gain, shortness of breath, orthopnea, or ankle edema. It is confirmed by physical examination, electrocardiography, echocardiography, and chest x-ray. Although digitalis, diuretics, and angiotensin–converting enzyme (ACE) inhibitors may relieve symptoms of systolic dysfunction, the subject with heart failure should limit remote wilderness ventures to those activities that do not cause excessive shortness of breath, that is, to the point of requiring breathing through the open mouth, or excessive fatigue.

Peripheral vascular disease, claudication, symptomatic carotid disease, and aortic aneurysms warrant caution in regard to the difficulty of return or evacuation in the event of incapacity.

Gastrointestinal Disorders

The prevalence of certain gastrointestinal disorders is increased among elders. Because a majority of older adults now live in the developed world, associated changes in diet and lifestyle have led to a constellation of common gastrointestinal disorders that Denis Burkitt called afflictions of “modern Western civilization.” These include appendicitis, diverticular disease, colorectal cancer, inflammatory bowel disease, and gallstones.^5,22

Some of the most common gastroenteric problems affecting elders in particular are constipation and diverticulitis. Constipation is a frequent complaint among 26% of elder men and 34% of elder women. A difference exists between the medical definition and the elder’s perception of constipation and their need for laxatives. Normal frequency of bowel movements ranges from three defecations per day to three per week. However, laxatives are used by 15% to 30% of elders on a regular basis. When such individuals find themselves in the wilderness, away from the convenience of their bathrooms, alteration in bowel habits, sometimes to the point of fecal impaction, may occur. Diverticulitis may flare at such times, requiring dietary change, stool softeners, and antibiotics. It is prudent to obtain a detailed history of bowel habits and medications before embarking on a wilderness venture. Dietary fruit, fiber, and grain with stool softeners for elders during a wilderness venture may help avoid impaction, rectal fissures, hemorrhoidal bleeding, fecal incontinence, and chafing.

Gastrointestinal disorders noted among elders may also include malignancies of the colon and pancreas, gastric ulceration that may bleed, especially after nonsteroidal antiinflammatory drug (NSAID) ingestion, and Helicobacter pylori infection. Prospects for bleeding or obstruction from colon malignancies, bleeding from gastric ulcers, and possible perforation of ulcers should alert the individual or group leader to the need for medical attention. A surgical emergency may arise from an incarcerated or strangulated inguinal or ventral hernia.

Diarrhea among elders contracted in Third World countries may be severe, leading to dehydration, gastrointestinal bleeding, or perforation of a hollow organ. Exacerbation of diverticulitis or acute cholecystitis (with or without pancreatitis), persistent or unusual abdominal pain, vomiting, bleeding, and worsening dehydration are reasons for ending the venture and initiating evacuation to medical care.

When traveling to remote countries, it is prudent for some expeditions to carry intravenous (IV) fluids and to consider appropriate antimicrobial prophylaxis or medications for the presumptive treatment of infectious diarrhea.

Genitourinary Disorders

Elders are particularly vulnerable to urinary tract disorders, including infections, obstructions, and ureteral, renal, or bladder stones. Bladder infections in women are common in remote settings because of dehydration and difficulty with hygiene. Incontinence after hysterectomy is frequent, and discomfort from chafing and bladder infection may be present. It is prudent for women to carry medicated skin pads and cotton diapers. Men may incur bladder infections from benign prostatic hypertrophy with obstruction. Anticholinergic medications may induce bladder relaxation with subsequent retention. Terazosin hydrochloride, an-α₁-selective adrenoreceptor blocking agent, may improve urine flow in instances of obstruction resulting from benign prostatic hypertrophy by reducing bladder outlet obstruction without affecting bladder contractility. On extended trips in remote areas, it may be prudent to carry a catheter for emergency relief of acute urinary retention.

Dehydration from fluid loss or inadequate oral replacement may precipitate infection. Adequate fluid intake is the key to genitourinary health in the wilderness, but the participant must be cautioned about water quality.

Menopause

Menopause is a normal phenomenon associated with aging. Rather than occurring as a discrete, definable event, the menopause transition may take place over a period of several years, beginning around 40 years of age or as late as 50 to 55 years of age. Also known as the climacteric, this is a time in life when the opportunity for leisure activities may be greatest. Women who participate in wilderness activities must deal with the symptoms and somatic changes of menopause in addition to the physical and environmental stresses of the wilderness.

Symptoms that foretell the onset of menopause include vasomotor flushing, night sweats, insomnia, vaginal dryness, and variations in menstrual cycle and flow. Convention accepts that 12 months of cessation of menses is a confirmation of menopause.

As ovarian production of estrogen declines, the androgen/estrogen ratio changes dramatically. Gonadotropin feedback results in increased follicle-stimulating hormone (FSH) in a range of up to 30 MIU/mL. Progesterone secretion is variable and may either increase or decrease.⁴² Resulting anatomic changes from these hormonal alterations may affect lipid ratios, the coronary arteries, cortical and trabecular bone, and changes in body fat distribution with a shift in fat toward the center of the body. Changes in cognitive functions have also been reported.

Vulnerability to osteoporotic fractures is a serious hazard for elder women in the wilderness. In trabecular bone found in the spinal column, resorption and formation occur 4 to 8 times as fast as within cortical bone. As a result, there is increased risk for compression fracture of the spine or fracture of the hip in the event of a fall.

Hormonal replacement therapy should be considered for menopausal or postmenopausal women or in those who have had a surgical hysterectomy. The three classic indications for hormone replacement therapy are (1) for symptoms related to estrogen deficiency, such as vasomotor symptoms or genitourinary tissue atrophy; (2) for prevention or treatment of osteoporosis; and (3) for prevention of cardiovascular morbidity and mortality, all of which may occur in the wilderness setting.

Combinations of estrogens and progestins may be used in treatment.³⁰ Examples include:

Transdermal route of administration may be convenient in the wilderness setting.

Musculoskeletal Disorders

Musculoskeletal disorders are common among elders. In the wilderness, joint stress associated with extended hiking, injuries from repetitive motion, falls, and other trauma, when superimposed on the aging body, can induce functional impairments. Limitations in mobility and from pain lead to loss of success or even to significant hazards during wilderness ventures.

Arthritis, found in about 15% of the U.S. population in 1990, is among the most common causes of disabilities in elders. More significant is a reported prevalence of nearly 50% among persons 65 years of age or older.

Musculoskeletal conditions with increased incidence in adults over age 50 years include osteoarthritis, osteoporosis, polymyalgia rheumatica, giant cell arteritis, gout (especially associated with diuretic use), and other crystal-associated arthritides such as calcium pyrophosphate deposition disease, basic calcium phosphate deposition disease, rheumatoid and other inflammatory arthritides, and spinal stenosis.

The aging joint undergoes degenerative changes in its components. Cartilage has very little ability to heal. Therefore injuries to cartilage tend to accumulate with age, leading to irreversible damage and osteophyte formation, developing into hypertrophic osteoarthritic change in joints of the extremities and spine.

Skeletal muscle undergoes specific age-related changes with loss of muscle mass. Changes in hormones, growth hormone/insulin-like growth factor-1 (GH/IGF-1), the androgen/estrogen ratio, cytokines/growth factor, interleukin-6, and free radical production may be related to these atrophic changes.

The syndromes causing loss of muscle mass in elders are either (1) intrinsic, from sarcopenia, resulting in diminished reserves of muscle mass, or (2) extrinsic, from failure to thrive (FTT) syndrome, diseases, or increased metabolic demands.

Prevention and treatment of sarcopenia and FTT include a regimen of exercise, including both aerobic training and strength training. Progressive resistance training (PRT) is effective in the treatment of sarcopenia. Lean body mass is lost along with bone mass at menopause. Estrogen replacement appears to be helpful in some postmenopausal women. Evidence supporting testosterone replacement for FTT in elder men is lacking.

A detailed history and physical examination, with emphasis on prior and present symptoms, is of value for an elder contemplating physical activity and essential for an elder planning remote wilderness activities. Although radiologic studies and laboratory tests may help establish a diagnosis, a common tendency is to rely too heavily on the radiograph to explain symptoms. Joint aspiration and synovial fluid analysis helps in diagnosis of metabolic or inflammatory arthritides.

Treatment of arthritis in a layered stepwise manner begins with rest, acetaminophen, NSAIDs, and topical capsaicin. Elders especially must be cautioned about gastric irritation from NSAIDs and their danger in the presence of comorbid conditions and anticoagulant therapy. Intra-articular corticosteroids may help reduce inflammation. Injection serves the extra function of providing access for aspiration of synovial fluid from a joint effusion. Viscosupplementation with hyaluronic acid injection has also been attempted to aid with lubrication of joints. This procedure is usually reserved for persons with mild to moderate osteoarthrtitis who have had poor response to oral analgesics, topical antiinflammatory gels, or physical therapy. Contraindications to such injections include infection at the injection site, systemic infection with fever, and patient on anticoagulants, such as warfarin. Effects from such injections may last up to several months. Excessive stress should not be placed on the joint for at least 48 hours after the initial injection.

Joint replacement, especially of the hip and knee, has made it possible for otherwise limited individuals to return to wilderness activities. The procedure, known as arthroplasty, is performed for relief of pain and enhancement of function in a joint whose cartilage has been damaged by trauma, infection, or arthritis.

In the traditional total hip replacement, the integrity of the prosthetic femoral head–acetabulum ball and socket joint is maintained.

Sometimes joint resurfacing is possible. In this procedure, the resurfaced joint is capped and a metal prosthesis may be possible. Smoothing, reshaping, and cementing the artificial joint leads to a 3- to 4-day hospital stay, especially with knee replacement, followed by 4 to 8 weeks of limitation, subject to variation based on age, general health, and other factors. Total rehabilitation after surgical hip replacement takes at least 6 months, and wilderness activity during that time should be discouraged.

There are risks from joint replacement, such as infection, clotting, embolization, dislocation, and breakage. Infection may occur immediately after surgery or years later and may result from infection elsewhere in the body. In the rare case when infection does not respond to antibiotic therapy, the joint must be replaced surgically. A temporary artificial hip, such as Prostalac, may be inserted for 3 months, allowing the patient some movement until the joint is permanently replaced.

Physical therapy before and after the onset of symptoms, including weight reduction, progressive resistance training, aerobic conditioning, and spa therapy, may be effective in treatment or when preparing for a wilderness venture. Corsets, braces, and canes prescribed by the treating specialist should be used, but the layperson is cautioned against self-prescription.

A conditioning program before the venture may help prevent musculoskeletal problems or may precipitate symptoms that alert the individual to a problem not previously recognized. It is better for symptoms to occur at home and serve as a warning for potential future untoward events than to occur in a remote location far from medical care. Because degenerative changes in the lumbar and cervical spine may become symptomatic, it is appropriate to carry a backpack during a conditioning program before a hiking venture. At least one and preferably two hiking sticks are recommended for hiking activities.

Neurologic Disorders

Organic neurologic disorders, clinically apparent or subclinical, are frequent among elders. Symptoms of neurologic problems may be precipitated by minor activities or environmental stresses in the wilderness. Physical activity, to which a participant may be unaccustomed, especially when extreme environmental conditions are superimposed, can make subtle changes more apparent. However, if a victim responds with denial, the result can be devastating.

A history of ischemic or hemorrhagic stroke that in the past resulted in a degree of paresis, especially when accompanied by symptoms such as dizziness, changes in rational thought, or seizure, should alert leaders to potential problems in a wilderness venture.

Altitude, especially above 2500 m (8200 feet), may induce changes in mentation not apparent at lower levels. Leaders should be especially diligent in the assessment of individuals with a previous history of altitude sickness or who are taking medications, including anticoagulants, for cerebrovascular disease.

The Senses

Our senses act as our warning system for hazards in the wilderness. The five classic sensory “instruments” of vision, smell, taste, touch, and hearing (including its vestibular function) send signals to the central nervous system during interpretation of the physical environment. With age, these sensors undergo functional degeneration. Up to 75% of elders have visual and auditory impairments not reported to their physicians. Changes may be subtle. The aging rule is 1% loss per year after age 30 years of physiologic function in most organ systems.

Neuropsychiatric Disorders

Situational stresses are often superimposed on environmental stresses during wilderness ventures. Difficulties with group interaction, changes in rational thought in individuals with organic brain disease, or behavioral upheaval from bipolar states can jeopardize the health and safety not only of the individual, but also of an entire group.

Problems associated with drug abuse or alcoholism are a danger to the individual and are potentially devastating to the group. Subtle alcoholism may evolve into full-blown withdrawal psychosis during a hypoxic event or during extreme physical exertion. Drug use in elders may not be “recreational,” but withdrawal from ethical drugs may still be quite severe. Leaders of wilderness ventures must recognize the danger of disruptive psychiatric problems and attempt to prevent them by careful screening before the venture.

As people age, a variety of cognitive disorders becomes apparent, including progressive dementia, confusional states, and cognitive disorders resulting from psychiatric syndromes. Symptoms may be precipitated in vulnerable individuals by physical or environmental stresses of the wilderness. The two usual sources of information concerning the status of patients are patients’ families and the patients themselves. It is rare for a family member to approach the physician with concerns about the cognitive function of a relative; thus an interview and brief mental status testing should be included in the medical examination.

A cognitive interview should provide the examiner with insight into prior cognitive skills and personality traits to serve as a baseline. Included should be the nature of the subject’s memory at that time, the interval since onset of symptoms, the nature of onset (slow or sudden), and current state of cognitive function.

Frontotemporal dementia, such as Pick’s disease, may manifest itself early with a change in personality marked by inappropriate and often volatile behavior. Alzheimer’s disease is frequently manifested by apathy and decline in ability to learn new information. Physician assessment of cognitive function and neuropsychiatric disorders may identify potential disaster during wilderness undertakings.

Diabetes Mellitus and Other Metabolic Disorders

Type 2 (“adult-onset”) diabetes mellitus, whether requiring insulin or controlled by oral hypoglycemic medication, is not necessarily a contraindication to wilderness activities; however, other problems related to diabetes may increase the risk for medical emergencies. Cardiovascular disorders, coronary artery disease, cerebrovascular disorders, peripheral and autonomic neuropathy, nephropathy, poor wound healing or infection, and vulnerability to frostbite and cold injury all may be associated with this metabolic disorder.

Insulin-dependent (type 1) diabetes is a very different situation because of the additional problems with caloric intake and energy expenditure. Hypoglycemic episodes may lead to accidents from mental confusion. The vestibular apparatus in elders is particularly sensitive to such episodes. The “buddy system” should be deployed to assist the insulin-dependent diabetic in the wilderness. Therapy for other metabolic disorders should be maintained as recommended by the endocrinologist.

Obesity

Almost two-thirds of adults in the United States are overweight and over 30% are obese, according to National Institutes of Health data collected from 1999 to 2000.⁴⁸ There is widespread recognition that weight has become a very significant problem affecting morbidity, mortality, health care services, productivity, and economic costs.

The term overweight refers to excess body weight compared with a set of standards. Excess weight may come from muscle, bone, fat, or body water. Obesity refers specifically to an abnormally high proportion of body fat. Because of their high proportion of muscle to fat, some athletes and body builders can be overweight without being obese. Obese people, however, are all overweight.

The most commonly accepted measure for determining overweight status is the body mass index (BMI), reflecting the relationship between height and weight. The BMI is derived from the following formula:

Overweight is identified by NIH as a BMI of 25 to 29.9 kg/m² and obesity as a BMI of 30 kg/m² or greater. The World Health Organization also recommends defining overweight as a BMI of greater than 25.⁴⁸

Illnesses associated with overweight and obesity include diabetes, hyperlipidemia, hypertension, heart disease, stroke, osteoarthritis, respiratory problems, sleep apnea, gallbladder disease, menstrual irregularities, complications of pregnancy, increased surgical risks, depression, and even certain forms of malignancy. Injuries, especially falls with fractures, warrant awareness and caution along trails in the wilderness. Respiratory difficulties and excessive fatigue are also frequent complaints among the obese in the wilderness.

Among people with type 2 non–insulin-dependent diabetes, 67% have a BMI greater than 25. Hypertension is found in 22.1% of men with a BMI greater than 25, but is found in only 14.9% of those with a BMI less than 25.⁴⁸ These figures indicate that weight is a risk factor and a predictor of illness. Life expectancy is shortened 2 to 5 years with moderate obesity. Obese people have a 50% to 100% increase in all-cause risk for premature death.⁴⁸

People with obesity-related problems are at risk if they happen to venture into the wilderness. In the event of an emergency requiring evacuation, more effort is required by rescuers of an obese victim as well as by the victim him- or herself.

Many obese individuals who recognize their problems may begin a weight reduction program that includes not only dietary controls but also exercise activities, especially walking. Energy expenditure while trail walking¹⁸ may be calculated from speed of walking and grade of the trail using the following formula:

Caloric expenditure may be calculated from this energy cost. The energy calculated from the above formula may be modified by the physical characteristics of the trail terrain such as soil, asphalt, scree, and snow. Terrain coefficients are available for estimating the increased energy expenditure while traversing difficult terrain.⁴¹

Until the overweight/obesity epidemic is controlled, obesity-related illnesses and injuries will continue to concern wilderness health care providers.

Pharmacology, Pharmacokinetics, and Polypharmacy

Older people are the major consumers of all categories of medications. Health status and pharmacokinetics of elders influence drug choices, dosages, prospects for adverse reactions, and even therapeutic goals. Physician assessment of elders before wilderness activities should include careful review of all medications.

Age-related physiologic changes that may influence pharmacokinetics include reduced gastric acid production and altered gastric emptying that affect absorption; reduced splanchnic blood flow that affects first-pass (or presystemic) clearance; reduced body water, serum albumin, body fat, and body mass that affect protein binding; changes in hepatic size and blood flow that affect hepatic clearance; and reduced glomerular filtration rate and renal tubular function that affect renal clearance. As a result, physicians recognize that it is almost always prudent to begin with a lower starting dose and lower maintenance dose of certain prescribed medications in elderly patients.

Renal clearance of some drugs is reduced as a result of aging. The clinical significance of altered renal clearance resulting in elevated blood levels is, of course, related to the drug. Drugs with a very narrow therapeutic ratio should be carefully monitored. These include antibiotics such as gentamicin, streptomycin, and kanamycin; β-blockers such as atenolol and sotalol; cardiac glycosides such as digoxin; and psychotropic drugs such as lithium.

Hepatic clearance of drugs is of even more concern in elders because of a silent reduction in clearance capacity of up to 50% or more in this age group. Causes of reduced hepatic clearance include reduction of absolute liver size, decrease in hepatic blood flow, and perhaps altered enzyme activities. Benzodiazepines, nitrazepam, chlordiazepoxide, midazolam, and colabazepam, eliminated primarily by oxidation, should be reduced in dosage. Oxazepam, eliminated by glucuronidation, also should be given in reduced dosage.

Comorbidity, the presence of multiple pathologic problems, makes drug choice particularly important because of the prospects of worsening a coexisting disease when a prescription is given for another disease condition. For example, thiazide diuretics may worsen control of diabetes; calcium channel blockers may result in ankle edema; β-blockers may increase symptoms of peripheral vascular disease; dopamine blockers given as antiemetics may exacerbate parkinsonism; and NSAIDs may render hypertension, heart disease, or renal failure more difficult to control. Counseling, packaging labels, diaries, and supervision are important instruments for proper control of toxic and side effects of medications in elders.

Excessive use of medicines is often seen.²⁹ Polypharmacy represents a less-than-desirable state of duplication of medications, failure to recognize potential drug interactions, and inadequate attention to pharmacokinetics and pharmacologic principles.³⁵ Alcohol abuse frequently compounds the problem of polypharmacy. It is a great help to have each participant carry all presently consumed medications to his or her physician for review before the wilderness venture.

Fires, Storms, and Natural Disasters

Anything can happen at any time in the wilderness. The suddenness with which fires, storms, and natural disasters can strike threatens not only safety but also survival. Elders, who may be less mobile and more vulnerable than are younger people, must be especially alert. They have no business struggling against the elements. For all of these events, the first rule is evacuate with the first warning. The second rule is maintain communication, if possible, if only one-way by radio. Small emergency radio receivers powered by batteries, photoelectric cells, or crank generators are inexpensive.

For elders, fire hazard does not simply mean flames; threats include fatigue, smoke inhalation, and possible cardiovascular emergencies associated with the exertion and excitement. Common sense measures that may help if trapped in the area of fire are to seek shelter inside, keep smoke inhalation minimal, avoid strenuous outdoor exercise, drink copious amounts of fluids, and keep containers of water and wet towels available.

Elders are more likely to have previously experienced the violence of meteorologic storms and realize that shelter is the critical defense. Injuries associated with such storms are sustained not only from the dynamics of the weather, but also from debris hurled as projectiles by the wind.

Falls and Safety

Falls are especially common in the wilderness setting and can lead to devastating environmental exposure. Risk-taking invites problems. Planning, prevention, and alertness are essential for safety.

Falls rarely occur because of a single cause; most often they are a result of the interaction among intrinsic deficits, activities, and environmental hazards. Intrinsic deficits among elders impair judgment, sensory input, reaction time, proprioception, balance, and gait. Medication effect often adds to the risk for falls. Individuals with these deficits are vulnerable to environmental hazards such as scree, rock, roots, water, and unstable footing. About one in four elders who falls sustains significant injury and about 5% of these falls result in fractures. It is not uncommon for a life-changing event such as this to be followed by progressive deterioration of health and vigor.

Effective prevention entails review and assessment of individual health status and the proposed wilderness activity by an experienced wilderness leader. On site, many find that a walking stick or a lightweight alloy pole helps with stability. Cell phones and radios may speed rescue of the injured. Precautions include:

Focused instructions are available through specialty organizations such as the National Ski Patrol, Outward Bound, National Outdoor Leadership School, and Princeton University’s Outdoor Activities Program, among others.

Medical Examination

By the time an individual qualifies for the designation “elder,” that person has usually made some arrangements for medical care, examination, and advice. However, as an elder considers a venture into the wilderness, there is often confusion or insecurity about the prospect of developing some form of medical problem. A medical examination may be necessary.

Components of the Medical Examination

A survey of wilderness leaders served as the basis for developing specific components of a medical examination for prospective participants in wilderness activities.^12,14,15 The five categories of characteristics included in the health examination are shown in Box 101-8.

BOX 101-8 Components of the Medical Examination

1 Personal characteristics, which provide a profile of the subject regarding age; gender; education; occupation; status as volunteer or recruit; history of a recent or remote similar venture; use of tobacco, alcohol, drugs, or steroids; history of psychological or interpersonal problems, especially during wilderness ventures; and history of participation in athletics.

2 Historical features, such as illness, with particular emphasis on cardiovascular, pulmonary, musculoskeletal, and neurologic problems; problems associated with a previous venture; intolerance to altitude, heat, or cold; psychological problems; accidents; and pertinent family history.

3 Medical examination, including examination of heart rate, blood pressure, precise cardiac examination (including auscultation), examination of peripheral pulses and carotid arteries, auscultation of the chest, abdominal palpation with rectal examination, musculoskeletal system with range of motion of joints and back, and height and weight.

4 Physiologic examination, which is only rarely required, depends largely on the nature of the venture and may range from simple simulation of the planned activity to functional aerobic testing for max using a treadmill, cycle, or step ergometry. Functional testing with electrocardiographic monitoring is frequently used for diagnostic testing and for predicting cardiovascular response to exercise. Testing by running for speed or endurance and evaluation of dynamic strength and agility are rarely used but are interesting during skill assessment. Testing for hypoxic ventilatory response (HVR) may be primarily of research interest but nonetheless should be considered if precision is needed for elders going to high altitude.

5 Psychological interviews largely depend on the skill and technique of the examiner and should attempt to uncover a history of previous difficulties with group interaction and team activities, or fears related to physical and environmental stress.

In this survey of wilderness leaders, the best predictors of a successful venture were found to be a history of similar successful venture and the psychological profile of the individual. The best single predictor of failure on a wilderness venture was difficulty with interpersonal relations. Consequently, the most important part of the medical examination before a wilderness venture was determined to be an in-depth interview by an examiner experienced in medical care and the nature of the venture. After the interview, appropriate medical, laboratory, radiographic, and physiologic studies may be performed.

The content of a medical examination, consisting of any or all of the five categories listed in Box 101-8, matches the characteristics of the individual with the characteristics of the venture and identifies the components of the medical examination that may be needed (Table 101-4).

TABLE 101-4 Construction of the Medical Examination of Prospective Participants in Wilderness Ventures

Counseling and Teaching Elders Before Wilderness Ventures: The Gray Eagles

The love of the wilderness fuels the spirit that hears the call of the wild. Aging seems only to sharpen this desire and to deepen its significance. One group of aging individuals who answered the song was the Gray Eagles (Figure 101-4, online), the brainchild of Memphis pathologist, Dr. John K. Duckworth and retired food executive, Mr. John C. Johnson.¹³ After years of recreational hikes, these seasoned outdoorsmen formalized their group in 1989. They invited individuals to participate in wilderness backpacking trips to such places as the Wind River Range in Wyoming, Banff National Park in Canada, the Beartooth Range in Montana, and the Olympic Range in Washington State. Their experiences have been invaluable in providing a unique opportunity to learn about the medical problems of groups in the wilderness.

FIGURE 101-4 The Gray Eagles. A, John C. Johnson, one of the founders, rides in a wheelbarrow while Dr. Justin Towner pushes. B, This group of senior outdoorsmen gathered 1 year after the 9/11 tragedy, memorializing those who suffered or died. C, Founder Dr. John K. Duckworth. D, Llamas help with the load.

(Courtesy Dr. John K. Duckworth and Mr. John C. Johnson.)

With a record of over 3500 person-days in the wilderness, this group has sustained very few serious medical problems. Most problems consist of consequences of environmental exposure, trauma, infectious processes, and neuropsychiatric disorders (Box 101-9). Fatigue, minor musculoskeletal problems, and manageable trauma were encountered relatively often. One successful year of participation by an elder person does not necessarily guarantee that the next year will be uneventful. With increasing age causing reduced reserve, an elder’s tolerance to the effort may change dramatically, and subtle symptoms may evolve into a full-blown emergency. Problems confronted by the Gray Eagles with the most serious potential have been behavioral aberrations from organic brain syndrome not previously recognized but precipitated by the environmental and physical stress of the venture.

From these experiences, the need for a structured program of preparation before undertaking the trip became apparent to the group. Analysis of the events of each trip led to a program that included:

As the Gray Eagles have continued to age, they have added llamas, mules, and horses to some ventures and incorporated river trips. Their experiences provide a unique opportunity to examine the effects on elders of wilderness activities and the effects of exposure, lightning, and other environmental hazards. The remarkably safe record of their trips could be attributed to precise planning, education of participants regarding any eventuality, and the requirement that each member of the group has a health review before the venture. The security of physician oversight was reassuring. These activities have provided new horizons for participants and their doctors.

Summary and Conclusion

Seniors in our society are encouraged to remain mentally, physically, and socially active. They perceive this recommendation as a welcome invitation to live life to its fullest. In response, elders in increasing numbers have come to enjoy the fellowship, camaraderie, and adventure of wilderness activities. Unfortunately, health risk associated with high-performance activities increases with age because of altered physiologic function, unrecognized impairments, or effects of illnesses and their treatment.

To reduce risk, seniors should be advised to temper their enthusiasm with the caution derived from the wisdom of experience. John Glenn made his second space flight safely at age 77 because of thoughtful planning and training. Nevertheless, a healthy respect for risk should not go to an extreme, where it becomes a fear that precludes wilderness experience entirely. The golden years hold many opportunities for adventure. Remember that the optimist sees sunset as sunrise in reverse.

Acknowledgments

The authors are indebted to John K. Duckworth, MD, Professor of Pathology, University of Tennessee College of Medicine, Memphis, for sharing his experiences, advice, photographs, and wisdom. The authors are also grateful to John C. Johnson of Durham, North Carolina, for sharing his memories and photographs.