Chapter 21. Evaluation of the Geriatric Patient

1. The elderly are the fastest growing segment of the population.

2. A healthy elderly patient may have normal organ function but less reserve.

3. There are normal organ and overall functional changes of aging that do not imply disease but must be considered when planning an anesthetic.

4. Elderly patients have a high incidence of chronic disease states.

5. Elderly patients do not require a "special" anesthetic but rather require strict attention to meticulous preoperative assessment, detailed management of intraoperative variables and concurrent disease states, and cautious titration of drug administration and dosages.

In developed countries the elderly population is growing at a remarkable rate, with considerable implications for perioperative health care. Elderly patients now account for more than half of all hospital care days in the United States. In addition, almost a third of all surgical patients are 65 years or older, with an even larger fraction anticipated in the next 2 decades. Virtually every nonpediatric hospital provides a wide range of surgical services for elderly adults; consequently, almost every anesthesiologist in contemporary practice is expected to have expertise in geriatric medicine as it relates to anesthetic practice.1

As they age, adults exhibit an increasingly varied array of physical responses to lifelong exposure to environmental and socioeconomic conditions and to the accumulated stigmata of prior traumatic injuries and medical therapies. Prolonged longevity also reveals all intrinsic physiologic strengths and weaknesses and full expression of genetic differences that might not be fully apparent over shorter life-span intervals. The terms elderly and geriatric are used synonymously in this chapter to describe patients who are 65 years or older. The term aged is used to describe individuals older than 80 years.

Neither elderly nor aged surgical patients require a "special" anesthetic. A well-conducted anesthetic of any type can be both safe and appropriate for an elderly patient if the anesthesiologist (1) adheres to high standards of preoperative assessment, (2) closely controls and monitors preexisting disease, and (3) pays meticulous attention to drug dosage and to the details of pain management and postoperative care.2 The sections that follow describe some of the current concepts of human aging that are relevant to contemporary anesthetic practice, examine common disease states, and review common surgical procedures in the elderly.

The exact mechanisms that control the aging process remain unknown. However, it is very clear that aging is not simply the result of accumulated disease. Aging is a physiologic phenomenon that manifests itself in mammalian species as universal and progressive degenerative changes in both the structure and the functional capacity of organs and tissues. The implied consequence of aging in all species is an increasing probability of death as a function of time. Currently, there is no consensus as to when the geriatric era begins in human subjects or whether any single physiologic marker can identify an elderly or an aged patient.

Theories proposed to explain aging broadly fall into 3 categories: genetic theories, in which gene-controlled programmed biologic clocks such as telomeres regulate growth, maturity and old age; neuroendocrine theories, where changes in neural function and hormones cause age related physiologic changes by interfering with cooperation between organs and impairing the response to external stimuli; and damage-accumulation theories, where damage to molecular structures progressively accumulates because repair and maintenance are always less than those required for immortalization. All these mechanisms are important and interrelated.

The Mitochondrial Free Radical Theory of Aging

Among all the single-cause theories that have been proposed, the mitochondrial free radical theory of aging is without doubt the most studied and the most widely recognized.3 It is thought that throughout adulthood, increasing levels of oxygen-derived free radicals, or reactive oxygen species (ROS), create oxidative stress within the mitochondria and disrupt the structural and enzymatic machinery of oxidative phosphorylation.4 Investigations of oxidative phosphorylation in aging mitochondria suggest that aging is associated with progressive impairment of bioenergetic efficiency and increases in the incidence of defects in DNA, primarily mitochondrial DNA (mtDNA), presumably because of increasing levels of ROS.5 As the ability of the cell to scavenge these by-products of aerobic metabolism declines, ROS may create a self-perpetuating "cycle of aging" within the mitochondria (Fig. 21-1).6 Many gerontologists have concluded that changes in mitochondrial bioenergetics largely explain much of normal human aging and that these appear to play a central role in the diffuse deterioration of cellular and organ function that characterizes human senescence.7

However, although it is clear that oxidative damage increases during aging,8 and it is difficult to doubt that mitochondria play a key role in the aging process,9 the fundamental question regarding whether mitochondrial oxidative stress is causal to the aging process remains unresolved. In fact, a number of studies on long-lived vertebrate species, mutants, and transgenic animals indicate that the concept that aging is triggered by the detrimental action of ROS, produced during normal metabolism, may not be accurate.10

Organ System Senescence

Age-related physiologic change was classically represented as a linear decline of maximal organ system function. The physiologic decline was believed to begin early in young adulthood and continue inexorably downward thereafter. However, contemporary analysis suggests that there is a more complex relationship, with relatively minor decrements in maximal organ function first becoming apparent just after peak of somatic maturation, in the fourth decade of human life. Additional decrements of average maximal function or functional capacity during the middle adult years also appear to be relatively subtle but subsequently become more obvious during the seventh decade of life and beyond (Fig. 21-2).

Nevertheless, although some decline of maximal function is inevitable, the competence of integrated organ system function varies greatly from one elderly patient to the next, even in the absence of disease. Functional capacity is significantly altered by differences in physical and mental activity level, comorbidities, social habits, diet, and genetic background. Those elderly patients who maintain greater than average functional capacities are considered "physiologically young." However, when organ function declines at an earlier age than usual, or at a more rapid rate, elderly patients are often described as "physiologically old."

In fact, the extreme variability of signs, symptoms, and physical presentation common among older patients is an essential characteristic of geriatric medicine.11 This is not surprising, given that human aging represents the interaction of many factors, some universal and some idiosyncratic (Fig. 21-3). In all healthy geriatric patients, however, maximal organ system function remains greater than basal demand at all ages. The difference between maximal organ system capacity and basal function defines organ system "functional reserve." Aging is also inevitably associated with a decrease in functional reserve, which also is considered a defining physiologic characteristic of human aging (Fig. 21-4).

Clinically, decreased functional reserve implies a universal and predictable increase in the susceptibility of elderly patients to stress- and disease-induced organ system dysfunction. Organ system functional reserve is the "safety margin" that is available to meet, for example, the additional demands for cardiac output, carbon dioxide excretion, or protein synthesis imposed on the patient by trauma or disease or by surgery, healing, and convalescence. It is therefore of great importance to the anesthesiologist, and preoperative testing in the elderly patient is most effective when it provides the anesthesiologist with a quantifiable assessment of functional reserve. Testing should be clinically directed according to symptoms and complaints referable to age-related disease or to functional decline suggesting erosion of physiologic homeostasis.12 However, although cardiopulmonary functional reserve can be assessed clinically using various exercise or aerobic stress tests, there are no comparable techniques for assessment of hepatic, immune, or nervous system functional reserve, at least at the present time. These require subjective clinical assessment and detailed clinical history and physical examination, with particular focus on activity levels and the ability to participate fully in the normal activities of daily life.

Aging, Metabolism, and Body Composition

Older adults of both sexes undergo significant atrophy of most metabolically active tissues, especially brain, liver, and kidney. In addition, normal aging, particularly in men, is associated with a progressive loss of skeletal muscle mass. In aged men, continuing loss of muscle and central organ atrophy eventually produces a significant decline in total body weight, often to levels less than those of young adulthood. In women, however, muscle and bone loss due to osteoporosis are largely offset by increasing body fat, and therefore total body weight usually returns toward, but rarely falls below, young adult values (Fig. 21-5).

Skeletal muscle and large well-perfused organs comprise the lean tissue mass (LTM) component of total body weight. Age-related loss of LTM plays a powerful role in altering perioperative metabolism, cardiopulmonary function, and the pharmacokinetics of anesthetic agents. The linear correlation between basal metabolic rate (BMR) and creatinine excretion suggests that decreased muscle mass is largely responsible for the age-related decline in BMR,13 although middle-age subjects have a slightly lower BMR than younger subjects even when they are comparable in body size, body composition, or activity.14 BMR decreases in parallel with the contraction of total body water (TBW) throughout most of adulthood, but a more accelerated decline in energy expenditure at rest occurs later in senescence, with kcal/d in the 10th decade only half that of young adults. There do not appear to be any gender-specific differences in the effects of age on BMR that are not related to body composition or activity. Nevertheless, because BMR for both men and women eventually decreases somewhat faster than can be explained from the decrease in LTM, lessened thyroid hormone activity may eventually limit the level of metabolic activity, as well as the mass, of lean tissue components.15

After the young adult years, TBW falls 10% to 20%. Virtually all of the age-related changes in body water content are limited to the intracellular compartments. Decreases in circulating blood volume, once believed to be inevitable, actually reflect deconditioning and dehydration and are typical only in bedridden elderly or those with essential hypertension.16 Plasma volume, red cell mass, and extracellular fluid volumes are well maintained in nonhypertensive elderly individuals who maintain reasonable levels of daily physical activity.

Decreasing LTM reduces the capacity for body heat production, and impairment of thermoregulatory vasoconstriction places elderly surgical patients at increased risk for inadvertent intraoperative hypothermia.17 In fact, intraoperative core temperature decreases at a rate twice as great as that observed in young adults under comparable conditions, and the time needed for spontaneous postoperative rewarming increases in direct proportion to patient age.18,19 Because muscle, liver, and other components of LTM provide storage for carbohydrates, aging limits the ability to handle a glucose challenge, even though the timing and the magnitude of insulin release is normal in the elderly. Consequently, aging may be associated with a loss of pancreatic islet cell sensitivity to hyperglycemia, the so-called glucoreceptor defect.20 Alternatively, age-related glucose intolerance may reflect antagonism of insulin's effect on target tissues.21 Thus fluid replacement with glucose-containing solutions should be limited to environments that permit frequent measurement of blood sugar levels in elderly patients.

Nutrition

Malnutrition, also known as undernutrition, is commonly encountered in the geriatric population. The prevalence of undernutrition in hospitalized geriatric medical and surgical patients is particularly high and often unrecognized, unless sought specifically.22,23 Furthermore, if left untreated, nutritional status continues to deteriorate during the inpatient stay.24 Moreover, mortality is considerably higher in the malnourished elderly medical patient, compared with those who are nutritionally replete.25 The etiology of undernutrition in elderly patients is multifactorial and includes (1) functional decline and social isolation from support systems, (2) anorexia associated with older age or chronic illness, (3) anatomic or gustatory impediments to mastication or swallowing, (4) neglect or abuse, and (5) insufficient financial resources.22

The postoperative effects of malnutrition are multisystemic with consequences such as poor wound healing, impaired immunity, and poor respiratory function.26,27 In postoperative patients, food intake may be suboptimal at a time when metabolic requirements are increased. Indeed, it is well established that malnutrition on admission may adversely influence clinical outcome in elderly patients with femoral neck fractures.28

Cardiovascular Function

Myocardial Stiffening and Diastolic Dysfunction

The heart, unlike other major organs, does not atrophy with age. The aging left ventricle is actually thicker and less elastic than its younger counterpart, exhibiting the physical characteristics of presbycardia.29 This is caused by, at least in part, an increase in collagen cross-linking in the myocardial cytoskeleton to which the myocytes are attached.30 Cross-linking may reflect the buildup of advanced glycation end products produced by the chemical transformation of sugar moieties normally found in tissues.31 Mitochondrial dysfunction has also been invoked as an explanation for the age-related changes in ventricular dynamics.32

Whatever the precise mechanism, the stiffer ventricle and atrium do not permit complete chamber relaxation until relatively late in diastole. Consequently, passive ventricular filling, which occurs during the early phase of diastole, is significantly reduced in older adults, producing a form of diastolic dysfunction (Fig. 21-6). As a result, the elderly are particularly dependent on the synchronous atrial contraction of sinus rhythm for complete ventricular filling and may experience significant increases in pulmonary blood volume during exercise.33,34 Small decreases in venous return, such as those produced by positive pressure ventilation, surgical hemorrhage, or venodilator drugs, can significantly compromise stroke volume if even minor cardiac dysrhythmias are present.

Cardiac Output

Resting cardiac index in healthy elderly subjects decreases slightly throughout adulthood and into senescence, but this is not evidence of degenerative cardiovascular change.35,36 To the contrary, reduced cardiac output at rest is an appropriate integrated cardiovascular response to the reduced metabolic activity that occurs because of age-related loss of LTM. Normal aging simply produces a smaller "aerobic machine" with reduced perfusion requirements. Under conditions of submaximal demand, myocardial contractility is well maintained, at least until the eighth decade of life.37 Short-term demands for increased cardiac output are first met by moderate increases in heart rate and then by increasing left ventricular end-diastolic volumes and pressures.

During vigorous aerobic exercise, the aging, but well-conditioned, heart can increase cardiac output to levels near those of younger adults by generating progressively larger stroke volumes through the Starling mechanism, a nonpathologic adaptation unique to older adults (Fig. 21-7).38 Nevertheless, although many aged individuals compete successfully in a variety of strenuous athletic events, aging does ultimately impose significant limitations of maximal aerobic power generation (maximal oxygen consumption: VO2max) by reducing both the inotropic and chronotropic responses to β-agonists and to autonomic reflex pathways.39,40 In general, however, peripheral factors, such as lactate production and musculoskeletal stiffness, and not cardiac reserve actually limit VO2max during strenuous physical exercise in older adults.35

Vascular Stiffening and Systolic Hypertension

Systolic hypertension with widening of arterial pulse pressure is a major cardiovascular risk factor.41 It is common in the geriatric population and reflects a gradual increase in large artery stiffness caused by fibrotic replacement of elastic tissues during the adult years.42 This reduces the ability of the aorta and large arteries to store hydraulic energy and increases vascular impedance to ejection of stroke volume. The end result of these changes is a progressive and sustained increase in left ventricular wall tension and myocardial workload that produces symmetrical ventricular hypertrophy and increased ventricular mass. Impedance to the ejection of stroke volume increases in older adults, even when systemic vascular resistance is unchanged.43 Increased vascular stiffness and loss of arterial cross-sectional area also increase the reflection of arterial pressure waves that produces the familiar "ringing" characteristics of radial artery waveform tracings in geriatric patients.

Autonomic Control

Aging affects the autonomic cardiovascular control mechanisms nonuniformly. Although the parasympathetic component of the arterial baroreflex is diminished, the baroreflex control of sympathetic outflow and the vascular response to sympathetic stimulation are maintained.44

Basal levels of catecholamines and sympathetic nerve activity are known to increase with age. Plasma norepinephrine levels gradually increase 10% to 15% per decade.45 However, in isolated ventricular myocytes the EC50 for isoprenaline is nearly doubled in the elderly.45 A consequence of the decreased contractile response to catecholamines is that the aging heart is more dependent on the Starling mechanism to maintain cardiac output.46

Elderly patients have a lower resting vagal tone, fewer muscarinic receptors, and a decline in muscarinic receptor function.45 This results in the lower parasympathetic activity observed in the elderly, which has been implicated in the diminished heart rate increase in response to atropine compared with young patients.47

Pulmonary Function

Pulmonary Mechanics

Loss of tissue elasticity occurs in the lungs as well as in the cardiovascular system, and all elderly individuals eventually demonstrate some degree of emphysema-like increases in lung compliance. However, calcification and stiffening of the costochondral joints of the thorax reduce chest wall compliance, so net pulmonary compliance does not increase but is usually unchanged.48 Within the lung parenchyma, fibrous connective tissue proliferates, and there is degeneration and cross-linking of lung elastin.49 Breakdown of alveolar septae also reduces total alveolar surface area, increasing both anatomic and alveolar dead space.

Loss of lung elastic recoil is the primary anatomic mechanism by which aging degrades the efficiency of pulmonary gas exchange.50 Small airway patency, normally maintained by elastic recoil, is compromised, and closing capacity increases to the point at which it becomes greater than the volume of the lung at rest.51 The elderly individual probably experiences closure of some small airways even before the end of exhalation, and chronic airway obstruction, detectable as "expiratory scooping" on flow volume loops, is increasingly common but often undiagnosed in senescence.52 Vital capacity is significantly and progressively compromised because residual lung volume increases at the expense of inspiratory and expiratory reserve volumes (Fig. 21-8).53 Because the changes in elasticity are nonuniform, they severely disrupt the normal matching of ventilation and perfusion within the lungs, increasing both shunting and physiologic dead space.

Informal but clinically valuable assessment of pulmonary function may be possible by questioning the elderly with regard to ability to climb stairs, provided that other causes for stopping, such as claudication, can be excluded. Inability to climb 2 flights of stairs correlates with a forced expiratory volume (FEV) that is less than 70% of predicted value, and failure to achieve 3 flights of stairs may predict severe pulmonary complications after thoracic surgery.54,55

Control of Respiration

The cardiovascular and ventilatory responses to imposed hypoxia or hypercarbia are delayed in onset and are of smaller magnitude in geriatric patients.56 However, the moment-to-moment neural control of ventilation and the responses to changes in pH and respiratory gases appear to be essentially unchanged.

Gas Exchange

Overall, pulmonary function in older adults during general anesthesia is best characterized as decreased efficiency of gas exchange as a consequence of significant ventilation-perfusion mismatch, primarily because of the deterioration of intrinsic recoil, disruption of alveolar architecture, and increased sensitivity to anesthetic- induced depression of active hypoxic pulmonary vasoconstriction.57 As a result, total venous admixture during anesthesia increases steadily with advancing age (Fig. 21-9).58 Although the strength and endurance of the ventilatory apparatus remain adequate to meet moderate demands, skeletal calcification and rising airway resistance increase the work of breathing in elderly subjects, predisposing them to acute postoperative ventilatory failure.59,60

Central Nervous System

With aging, independent of comorbid processes, the brain undergoes a series of deleterious changes. These include gray and white matter atrophy (resulting in reduced brain size and expansion of cerebral ventricles and sulci), synaptic degeneration, blood flow reductions, and neurochemical alterations. These changes are complex and associated with large interindividual variability. There is, however, a pattern of selective loss and preservation.

Brain Atrophy

Longitudinal structural magnetic resonance imaging studies have demonstrated a gradual decline in gray matter volume with advancing age.61,62 In general, these studies suggest that although age is associated with generalized reduction in brain volume, the prefrontal cortical regions are more significantly affected than the rest of the neocortex, with the primary visual cortices maintaining their integrity.62 The mechanisms of differential brain atrophy are unclear, but vascular risk factors, even at moderate levels, may significantly accelerate its pace.62 Hippocampal volume is thought to remain relatively stable with age in healthy elderly adults without concurrent hypertension. The relative resilience of hippocampal volume to aging makes hippocampal deviations from normal size a sensitive indicator of pathology, such as vascular or Alzheimer dementia.62 The loss of brain volume appears not to result from cell death but rather from lower synaptic densities in older adults.63 Compared with gray matter decline, the decline in white matter volume begins later in life and continues at a more accelerated rate.61 Diffusion tensor imaging indicates white matter decline in healthy older adults most likely reflects myelin deterioration.64

Neurochemical Alterations

In addition to the structural effects of aging, there are prominent differences in brain neurochemistry between young and older adults. Progressive, although regionally variable, decrements in dopaminergic and cholinergic signal transduction mechanisms are well described.65 These are thought to be the result of both pre- and postsynaptic mechanisms. Decreases in the elderly brain neurotransmitter reserves are manifested by decreases in functional activities of daily living and increased sensitivity to anesthetic medications, in particular drugs that might precipitate extrapyramidal symptoms or anticholinergic syndrome. Decreased levels of acetylcholine and dopamine have been implicated in age-related cognitive and behavioral deficits, and they may therefore potentially contribute to postoperative cognitive dysfunction.66,67

Cerebral Blood Flow

Throughout the adult life span, healthy aging is associated with a 5% per decade reduction in positron emission tomography measures of cerebral blood flow, cerebral blood volume, and cerebral metabolic rate of oxygen in cortical and subcortical regions.68,69 These reductions can largely be accounted for by the reduction in brain volume associated with aging; flow-metabolism coupling, oxygen extraction ratio, and cerebral autoregulation remain intact.70,71

Hepatic, Endocrine, and Immune Systems

The age-related changes in hepatosplanchnic function are predominantly quantitative rather than qualitative.72 Liver tissue mass decreases approximately 40% by age 80 years, and hepatic blood flow is proportionally reduced, primarily because of decreasing portal perfusion.73 Hepatic enzyme activities are comparable with those of young adults, but there is great variability of metabolic function that may reflect loss of hepatocyte density.74 Plasma concentrations of transaminase and other hepatocyte-derived enzymes are similar to those of young adults, but the bromsulfophthalein retention test is prolonged with increasing age, approaching the upper limit of normal in the seventh decade of life.75 Functional capacity for nitrogen clearance is also progressively reduced in aging adults, as is galactose elimination—both to an extent somewhat greater than can be accounted for based on changes in liver blood flow alone.76,77 As a result, hepatic biotransformation and protein synthesis, although adequate to meet modest increases in metabolic demand, may easily be overwhelmed by the metabolic demands of trauma, disease, or surgical intervention, especially if associated with arterial hypotension, low cardiac output, hypothermia, or direct hepatic injury.78 Loss of hepatic functional reserve also explains the reduced rates of plasma clearance and prolonged clinical effects of narcotics and many other xenobiotics in geriatric subjects.79 Overt hepatic dysfunction and failure appear in approximately 4% of elderly surgical patients, but more subtle degrees of hepatic compromise and limited hepatic functional reserve produce many postoperative complications and may require supportive therapy and intensive care.80

Aging appears to have little effect on macrophage and other aspects of phagocytic activity, but even fit elderly subjects exhibit subtle evidence of decreased immune responsiveness and specificity. As people age, the ability of the immune system to distinguish "self" from "nonself" antigens is reduced, increasing the prevalence of autoimmune phenomena and decreasing resistance to infection.81,82 The effects of aging on mitochondrial function and control of apoptosis may play an important role in this process.83 Thymic involution at sexual maturity is associated with marked changes in lymphocytic balance that progresses through senescence. Older adults have decreased B- and T-cell lymphocyte activity and depressed serum titers of immunoglobulin E, depressed skin response to exogenous allergens, and impaired delayed hypersensitivity.84 Older adults are particularly predisposed to streptococcal pneumonia, meningitis, and septicemia. Sepsis is second only to respiratory failure as a cause of morbidity and mortality in elderly trauma patients.85

Adrenal tissues also show evidence of age-related atrophy, and cortisol secretion declines at least 15% by 80 years of age, although plasma levels of cortisol remain similar to those of younger adults because of reduced rates of degradation. Similarly, in the pituitary-thyroid axis, thyroxine levels are relatively unchanged, but there is a damped pituitary response to thyrotropin-releasing factor and decline of thyroid-stimulating hormone (TSH) levels, although the end-organ cellular response to TSH is not affected by age.20,86 However, plasma concentrations of norepinephrine are 2- to 4-fold higher in elderly subjects than in younger adults during sleep, at rest, and even in response to exercise-induced physical stress.87 These are rarely apparent clinically in elderly patients because aging markedly and progressively depresses β-adrenergic end-organ responsiveness, producing, in effect, endogenous β-blockade.88 In contrast, there appears to be little change in α-adrenoceptor or cholinoreceptor activity.89

Renal System

As people age, there is a progressive reduction in renal tissue mass and renal blood flow (Fig. 21-10). Renal plasma flow, glomerular filtration rate (GFR), and, most important, creatinine clearance decline significantly.90 These deficits are further exacerbated by decreased perfusion caused by cardiovascular system aging and superimposed disease.91 One must be wary of perioperative fluid balance, potential electrolyte imbalance, and the potential for impaired renal metabolism of perioperatively administered medications. Of note, a "normal" plasma creatinine concentration may not indicate normal renal functional reserve in the elderly patient because creatinine load is greatly reduced by atrophy of skeletal muscle mass. Calculated creatinine clearance remains the most sensitive marker of renal function in the elderly.90

Polypharmacy

The high prevalence of disease in an elderly surgical patient population exposes them not only to the stigmata of the disorders themselves, but also to the risks of polypharmacy from the drugs used for medical therapy.92 Recent surveys reveal that more than 90% of persons older than 65 years use at least 1 drug per week, 40% take 5 or more drugs, and 12% to 19% use 10 or more medications in a week.93 Elderly patients account for 30% of all drug prescriptions, approximately twice the rate expected from their representation in the general population, and they consume 40% of all over-the-counter medications.94 Adverse drug interactions occur more often in older than in younger patients because polypharmacy is more common in older adults, and the reduced hepatic and renal functional reserve of the elderly patient prolongs both the desired and the unwanted effects of their medications.

A detailed medication history is an important part of the geriatric patient's preoperative evaluation. However, inaccurate reporting is common, and it may be necessary to request that patients bring all their medications or a complete list for review by the anesthesiologist.95 All medications should be carefully reviewed with the specific aim to identify potential interactions.96 Although it is appropriate to maintain elderly patients perioperatively on all medications needed to effectively control the symptoms of their disorders, especially cardiovascular, neurologic, and metabolic disease, some drug interactions may complicate perioperative management or make the pharmacokinetics of drugs used perioperatively less predictable.97

Volatile Anesthetic Agents

The effect of nervous system aging on requirements for general anesthesia is well established.98 Between young adulthood and the geriatric era, relative minimum alveolar concentration values for the newer inhalational agents decline by approximately 30%, the same decrement seen with older anesthetics such as cyclopropane (Fig. 21-11).99,100 However, the mechanisms producing this age-related increase in pharmacodynamic sensitivity to anesthetic agents remain unknown. Declining neuronal bioenergetics as a consequence of mitochondrial genetic mutation or because of age-related oxidative stress reduce anesthetic requirement, but it is not yet established that this, in fact, explains the reduced anesthetic requirement in the elderly.101,102 Given this empirical phenomenon, however, agedness itself may be an indication for additional monitoring of anesthetic depth using a processed electroencephalogram or similar device.103

Intravenous Anesthetic Agents and Opioids

Clinical experience suggests that there are significant age-related reductions in the dose requirements for virtually all anesthetic agents that depress consciousness.104,105 However, pharmacologic data for the effect of aging on the dose requirements for opioids, barbiturates, and benzodiazepines are less consistent than those for inhalational anesthetics. Most studies suggest that aging increases brain sensitivity to narcotics, but the effects of aging on the pharmacodynamics of barbiturates or etomidate are less impressive.106-109 Plasma drug concentrations immediately after intravenous injection are usually higher in elderly than in young adults.110 Consequently, there remains considerable controversy as to whether the clinically apparent age-related increase in the potency of these drugs is truly a pharmacodynamic phenomenon or whether it simply reflects age-related changes in the "alpha" or early phase redistribution pharmacokinetics of injected agents.

In any case, the concentrations of short-acting intravenous (IV) agents in plasma change so rapidly and in such a complex manner that the 2-compartment pharmacokinetic model used in traditional pharmacokinetic studies may be of little value for studying the early or "alpha-phase" behavior of these drugs and their subsequent redistribution in elderly subjects.111 Because the interaction between subtle changes in both pharmacodynamics and redistribution pharmacokinetics is sufficiently complex and unpredictable, some researchers believe that it must be characterized for each drug to predict the implications of aging on IV drug dosage.112

The net effect of age-related structural and functional changes within the nervous system on pain-related neurologic function remains controversial. The study of the amplification, modulation, and selectivity of afferent input within the spinal cord, thalamus, and other locations within the aging nervous system does not yet permit broad generalizations regarding aging and perception of pain.113,114 In addition, optimizing postoperative pain management in older adults may be further complicated by cognitive impairment and by unrealistic fear of opioid side effects.115 Perceived intensity of perioperative pain also appears to depend far more on anxiety, personality, and the prospect of long-term debility or disfigurement than on age itself.116 Nevertheless, the classic observation that opiate requirements are inversely related to patient age and essentially independent of body weight remains a useful and valid general guideline.117

Neuromuscular Blocking Agents

Although the elderly have reduced skeletal muscle mass, disseminated neurogenic atrophy at the neuromuscular junction allows proliferation of extrajunctional cholinoreceptors. An increased density of cholinoreceptors at the muscle end plate implies that increased concentrations of neuromuscular blocking drugs are needed to produce competitive blockade. In fact, the median effective dose and steady-state plasma concentration required for half-maximal neuromuscular blocking effect (median effective concentration) remain virtually unchanged, or may actually increase slightly, in the elderly patient.118 Maximal relaxant effect is delayed in onset relative to that produced in young adults, and duration of blockade is prolonged for relaxants with hepatic or renal elimination because plasma clearance declines with increasing age.119-122 Significant interindividual variability in the duration of neuromuscular blockade has been described with rocuronium and vecuronium in elderly patients.123,124 This unpredictability may be an important contributor to residual neuromuscular blockade in elderly patients. Relaxants, such as cisatracurium, that do not require organ-based elimination may provide more consistent duration of clinical effects.123,124 In elderly patients with limited functional reserves, it is therefore mandatory that quantitative neuromuscular monitoring be used to guide maintenance dosing, determine the optimum time for antagonism (train-of = four count = 4), and document the full return of neuromuscular function (train-of-four ratio >0.9) before extubation.125 Solely relying on expectations of the pharmacokinetics of relaxant elimination and clinical signs such as sustained head lift cannot be justified.125,126

Antagonism of neuromuscular blockade with an anticholinesterase or sugammadex should be routine in all geriatric patients.126 The cardiac muscarinic effects of anticholinesterases, such as bradycardia and conduction defects, are more pronounced with neostigmine (35%) than with pyridostigmine (14%) in elderly patients.127 Although studies in elderly patients are still lacking, sugammadex has been shown to be safe in clinical trials and free from any significant cardiovascular effects.128 It does not interfere with acetylcholine metabolism and there should therefore be no effect on the cardiovascular system or smooth muscles and no increase in secretions. There is no requirement to add an anticholinergic drug when giving sugammadex, thereby avoiding any possible side effects due to anticholinergic drugs.

The functional capacity of organs reduces with age, resulting in decreased reserve, decreased compensation for stress, and increased incidence of coexisting diseases. Coexisting diseases further depress organ function, leading to even greater risk with surgical procedures. It is useful to review the common diseases encountered in the elderly.

Cardiovascular Disease

The elderly patient is likely to suffer from altered cardiovascular function. Common disease states include coronary artery disease, cardiac valvular disease, congestive heart failure (CHF) and diastolic dysfunction, abnormal heart rhythm, systolic hypertension, and peripheral vascular disease.

Coronary Artery Disease

The presence of coronary artery disease (CAD) increases with age. Anatomic CAD can be detected in more than 50% of people older than 70 years (Fig. 21-12).129 CAD in the aged is more severe and diffuse than in younger patients.130,131 There are differences in prevalence by gender: At 65 years of age, CAD is more prevalent in men than in women; by age 80, the prevalence of symptomatic congestive heart disease is nearly equivalent in men and women.131 Despite the high prevalence of anatomic CAD, only 10% to 20% of people older than 65 years carry a diagnosis of active CAD.131 This may be a result of misdiagnosis, lack of clinical symptoms because of inactivity, or lack of recognition of risk factors leading to diagnosis. One study reported that 37% of elderly patients had subclinical CAD, making it as common as clinically overt CAD in older adults.132 Furthermore, in this study, the presence of subclinical CAD was significant because it strongly predicted overt CAD, stroke, and mortality, even after adjustment for traditional cardiovascular risk factors.132 Despite the high prevalence of CAD, over the last 30 years in the United States, the CAD mortality rate has decreased significantly. This includes reduced recurrent myocardial infarction and increased postmyocardial infarction survival.

Cardiac Valvular Disease

Aortic Valve

The mitral and aortic valves may undergo significant age-related dysfunction. Common causes of valvular heart disease in the elderly are degenerative calcification, myxomatous degeneration, papillary muscle dysfunction, and infective endocarditis.133

The most frequent valvular lesion in the elderly is degenerative calcified aortic stenosis, with a prevalence of 2.5% at the age of 75 years and of almost 8% at 85 years.34Aortic regurgitation, mostly mild, was found in 29% of the entire study cohort. The severity of aortic stenosis in the elderly is often underestimated because its progression is so gradual and because symptoms may be attributed to normal aging, but stenosis severity may progress rapidly after age 80.135 Common causes of aortic valve stenosis are calcification of a congenital bicuspid aortic valve, degenerative aortic stenosis, and rheumatic heart disease (which may coexist with mitral valve disease).

Mitral Valve

Mitral valve disorders are common in the elderly, but the symptoms of mitral valve disease may be masked or exacerbated by coexistent CAD, pulmonary disease, hypertension, and other systemic disorders that commonly occur in older adults.136 Chronic mitral regurgitation is the most common type of mitral valve disease in the elderly. Rarely, isolated chronic mitral regurgitation occurs as a consequence of papillary muscle dysfunction after myocardial infarction. Chronic mitral regurgitation may also be a result of mitral annular calcification, myxomatous valve degeneration (with mitral valve prolapse), chordal rupture, and rheumatic heart disease. Mitral annular calcification occurs in approximately 6% of people older than 60 years, predominantly in women. The incidence of myxomatous valvular degeneration increases with age.

Mitral stenosis is a disease of younger patients because severe mitral stenosis usually leads to surgery or death before 65 years of age.136 If present, mitral stenosis is usually a result of rheumatic heart disease, a common condition when the current elderly population was young. Less commonly, mitral stenosis develops because of progressive mitral annular calcification.

Tricuspid Valve

Tricuspid regurgitation is usually a result of annular dilation caused by right ventricular failure (usually resulting from left-sided heart failure) or pulmonary hypertension. Unlike in younger patients, infective endocarditis is a less common cause of tricuspid valve dysfunction. Tricuspid stenosis is rare in the elderly.

Pulmonic Valve

Pulmonic valve disease as a consequence of primary valve dysfunction is rare but is usually secondary to pulmonary hypertension.

Concurrent Valvular Disease

Concomitant mitral and aortic valve disease is common in the elderly. About half of patients with rheumatic mitral regurgitation have associated aortic valve disease, usually aortic regurgitation. In one study, concurrent mitral regurgitation found in elderly patients undergoing isolated aortic valve replacement (AVR) was found to be an independent risk factor for long-term survival.137

Systolic Hypertension, Diastolic Dysfunction, and Congestive Heart Failure

As reviewed earlier, diastolic dysfunction and systolic hypertension are common and increase with aging. Ninety percent of Americans who have a healthy blood pressure at 55 years of age will have hypertension when they reach 75 years of age.138 Another common problem in the elderly is chronic heart failure, which can be divided into 2 broad categories: systolic heart failure and diastolic heart failure.139 Diastolic heart failure occurs more frequently in the elderly, in women, and in those with systolic hypertension, but it is less associated with concurrent CAD than systolic heart failure.139

Peripheral Vascular Disease

Peripheral vascular disease is not a normal consequence of aging but is associated with systemic atherosclerosis and other risk factors for CAD, many of which are commonly found in the aging patient. The prevalence of peripheral arterial disease increases with age and has a variable presentation: asymptomatic, associated with intermittent claudication, or associated with critical limb ischemia.140

Abnormal Heart Rhythm

Age-related changes in atrial chamber size and pressure, in left ventricular mass, and in catecholamine levels, in addition to increased incidence of CAD, contribute to a higher incidence of arrhythmias and conduction disturbances in the elderly. Common arrhythmias are atrial fibrillation, ectopic beats, and heart block.

Atrial Fibrillation

Atrial fibrillation (AF) is among the most common arrhythmias seen in the general population.141 The prevalence of this condition is increasing and increases with age; it occurs in approximately 6% of people older than 65 years as compared with approximately 2% of people between 40 and 65 years of age.142 In all age groups, men are more affected than women. It is believed that by 2050, more than 5.6 million people will have AF and that more than 50% of those older than 85 years will have this condition.143 Multiple conditions predispose to AF, including structural heart disease, hypertension, CAD, heart failure thyrotoxicosis, sick sinus syndrome, and amyloidosis. Further, AF is common after certain procedures such as cardiac surgery with a perioperative incidence up to approximately 35%. AF is not a trivial rhythm because it increases morbidity and mortality, usually due to stroke.

Heart Block

There is a striking increase in the incidence of bradydysrhythmias and conduction abnormalities associated with progressive fibrosis in both the sinus node and atrioventricular conduction system in the elderly; sinoatrial pacemaker cells decrease progressively from 60 years of age such that approximately 10% of the cells are still present at age 75, while fat can also accumulate, serving to separate nodal tissue from the atria musculature.144 Bradydysrhythmias may be present preoperatively but can initially present as unexpected heart block under general anesthesia.145

Pulmonary Disease

Emphysema and chronic pulmonary obstructive disease are not associated with normal aging but are the consequences of exposure to environmental toxins, such as tobacco, which may vary among populations. One study from Norway estimated that in people older than 70 years, 11% reported having at least one current obstructive pulmonary disease, 8% reported daily wheezing, and 12% reported significant dyspnea.146 However, they noted that the only respiratory symptom or disorder to show any clear age-related pattern was dyspnea, which increased through 89 years of age before decreasing.

As noted, because of declines in immunologic function, the elderly person is more prone to pneumonia than a younger person. Furthermore, there may be an increased risk of aspiration pneumonia as a result of other conditions such as gastrointestinal sphincter malfunction or altered mental status.

As is expected in an aging population, the absolute number of patients with lung cancer is increasing. Historically, there has been a reluctance to treat elderly lung cancer patients aggressively because of a lack of supportive data and concern for potential toxicity. However, the bulk of evidence suggests that healthy elderly patients can benefit from therapy in all stages of non–small cell lung cancer and that the decision to offer therapy should be based on comorbidities and performance status rather than age.147

Gastrointestinal Disease

Although most gastroenterologic disorders that develop in younger people may also develop in the elderly, the presentation, treatment, and prognosis may be different.148 Disorders that may have a higher incidence in the elderly include peptic ulcer, ischemic complications of vascular abnormalities, drug-induced disorders, malignancies, and passive reflux. Competent upper and lower esophageal sphincters should not be assumed, leading to the increased risk of silent aspiration. Also important to consider in the perioperative patient is the high likelihood of a gastrointestinal side effect of a medication such as a nonsteroidal anti-inflammatory agent.149 Furthermore, there may be an increased risk of constipation and bowel obstruction with opioids in the elderly.

Renal Disease

Known decreases in renal function and GFR lead to a high incidence of mild chronic renal insufficiency. Progression to chronic kidney disease is associated with a high risk of renal failure, cardiovascular disease, and death.150 Many common comorbid disease states contribute to the increased incidence of renal dysfunction, including systemic hypertension, systemic arteriosclerotic disease, and chronic CHF. Regardless of the cause, the severity of chronic kidney disease can be classified by GFR (Table 21-1). Albuminuria is also used for diagnosis of renal dysfunction. This is a common problem because 18% of people older than 60 years have albuminuria, and 7% have an estimated GFR less than 60 mL/min per 1.73 m2.151 In people 70 years or older, those percentages increase to 30% and 26%, respectively.151

The diagnosis of renal dysfunction is indirect as GFR is estimated from the serum creatinine concentration or with creatinine-based estimations. One should not rely on creatinine alone; equations for GFR estimation should incorporate additional demographic and clinical variables.

Other problems to consider include urinary tract obstruction, common in elderly patients with an increased rate of benign prostatic hypertrophy, urinary incontinence, and a high incidence of silent urinary tract infections that may lead to perioperative infections or even urosepsis if left untreated.

Musculoskeletal Disease

The known changes in the musculoskeletal system lead to predictable disorders, including tendon and ligament tears, especially in the rotator cuff, the biceps tendon, the quadriceps tendon insertion to the patella, the Achilles tendon, and the posterior tibial tendon. A large study in the United Kingdom identified the odds ratio of an Achilles tendon rupture to be 6.4% in patients ages 60 to 70 years and 20.4% in patients age 80 years or older.152 There is also an increased incidence of osteoarthritis with age. Less clearly associated with aging but with a high incidence in the elderly patient is rheumatoid arthritis.153 These conditions are associated with known problems with airway manipulation and positioning. Spinal column intervertebral disk degeneration with disk herniation and osteophyte formation is progressive in the elderly and may lead to cauda equina or nerve root impingement and symptoms of spinal stenosis. Other conditions include polymyalgia rheumatica, gout, and pseudogout.

Endocrine Disease

Several endocrine disorders occur frequently in the elderly, including thyroid disorders, diabetes, and androgen deficiency.154 Glucose intolerance is especially important to assess, and thyroid disease is an underappreciated cause of morbidity in the elderly patient. A study of 3,233 individuals age 65 years or older showed an association between subclinical hyperthyroidism and development of atrial fibrillation.155 However, this study did not support the hypothesis that unrecognized subclinical hyperthyroidism or subclinical hypothyroidism is associated with other cardiovascular disorders or mortality.

Neurologic and Mental Status Disease

Starting with middle age, there is a progressive decrease in learning and memory, a factor to consider when assessing the ability of an elderly person to cooperate with perioperative care. An interesting hypothesis is that this is not caused by loss of the ability to generate new neurons but rather to a reduction in the decline of growth factors (fibroblast growth factor-2, insulin-like growth factor-1, and vascular endothelial growth factor) necessary for new neuron growth.156 There is also an increased occurrence of all forms of dementia, including Alzheimer dementia and neurologic disorders such as Parkinson disease.157

The risk of suffering a stroke increases linearly with age and is associated with other forms of cardiovascular disease, especially atrial fibrillation. For example, the proportion of strokes with AF in the United States is 6.2% for patients who are 50 to 59 years of age, 7.3% for patients 60 to 69 years of age, 16.5% for patients 70 to 79 years of age, and 30.8% for patients 80 to 89 years of age.158,159 Other causes of stroke are hypertension, cerebrovascular disease, myocardial infarction, structural heart disease, and cardiomyopathy. A history of neurologic dysfunction before a procedure may predict persistent increased cognitive dysfunction.160

Depression is very common in the elderly, with fewer reported symptoms than in younger people.161 It is estimated that more than a third of hospitalized elderly patients may suffer from depression.162 Not only does depression lead to increased symptoms from medical illness and increased use of health care resources, but it may affect the patient's ability to cooperate with preoperative conditioning and postoperative rehabilitative care. Interestingly, depression may be related to disturbances in other systems, such as the hypothalamic–pituitary–adrenal axis, cerebrovascular disease, inflammatory conditions, and nutrient deficiencies.163 Another condition to be aware of in the elderly is alcoholism, with implications for perioperative withdrawal and malnutrition.164

Ophthalmologic Disease

Visual impairment is common in elderly and aged patients. The most common causes include presbyopia, macular degeneration, cataract formation, diabetic retinopathy, and glaucoma. Untreated, visual impairment leads to physical handicap, increased incidence of falls, depression, social isolation, and dependency.165 Visual diseases and the medications used to treat them must be considered with the choice of anesthetic agents. Furthermore, perioperative disorientation or delirium may be in partly a result of declines in visual stimuli.

Hearing Impairment

Hearing loss occurs linearly with age, but the variation in hearing thresholds is large. Possible explanations include precipitating medical conditions, coexisting diseases, prior environmental exposure (especially occupational), and undefined genetic contributions.166 Hearing impairment may also contribute to postoperative delirium.

Oncologic Disorders

Worldwide, the incidence of cancer in the elderly continues to rise with more than 50% of all cancers and approximately 70% of cancer deaths occurring in patients age 70 years and older in developed countries.167 However, the use of combined modality therapy may improve survival in a variety of malignancies in the elderly, despite the known risks of chemotherapy. Although the elderly are less well studied in clinical trials, age itself should not be used as a criterion for denial of cancer therapy. Rather patients should be carefully selected and evaluated for life expectancy, performance and nutritional status, social support, and presence of medical or social conditions that may impede therapy.168 Decisions should also be made with respect to the anticipated benefit in quality or quantity of life.

Currently, more than 20% of people older than 60 years undergo surgery and anesthesia as compared with fewer than 15% of those ages 45 to 60 years. These proportions are expected to increase in the future. Despite the higher numbers of elderly patients having surgery, mortality and morbidity rates have been declining.169

Because all types of surgical operations are being offered to increasingly older people, it is important to differentiate the effects of aging from the pathology of individual disease processes and to control for comorbid conditions. In general, preoperative testing is not determined on the basis of age but in consideration of the procedure, the coexistent disease states, and the overall condition of the patient.170 However, it is reasonable to search for common, but perhaps asymptomatic, comorbid problems, such as subclinical cardiac disease or glucose intolerance. Common procedures in the elderly are briefly reviewed next.

Cardiac Surgery

All types of cardiac procedures, including coronary artery bypass grafting (CABG), valvular repair or replacement, and ventricular assist device placement, are being offered to older patients, even those patients older than 80 years. The morbidity and mortality of these procedures increase with age, but the benefits are a greater life expectancy as well as a better quality of life.

In-hospital mortality for CABG is approximately 8% for patients older than 80 years and is similar in highly selected patients older than 90 years.171 Although there are limited studies, the data appear to suggest that elderly patients at higher risk have better outcomes with revascularization than with medical therapy alone.171,172

AVR-combined procedures (AVR and CABG) and, to a lesser extent, mitral valve surgery are increasingly offered to the elderly. The risk appears to be similar to CABG alone; 2 authors reported in-hospital mortality rates of 7.9% and 8.5% for mitral and aortic valve surgery, respectively.173,174, Certainly age and comorbid disease states play a role both in morbidity and mortality but also in the choice of valve repair versus the type of prosthetic valve use.175

Heart failure is an increasingly common problem, which affects more than 5 million Americans and 15 million Europeans.176 Left ventricular assist devices have evolved as destination therapy for advanced heart failure patients who are not candidates for heart transplant, leading to a significant increase in use in elderly patients with this condition.177 This surgical procedure is likely to increase over time as the population ages and patients reach the limit of effective medical management for advanced heart failure.

Vascular Surgery

Vascular disease is prevalent in the elderly population, with major vascular procedures most commonly performed to treat the effects of peripheral vascular disease and carotid artery atherosclerosis. Therefore many elderly patients undergo aortic repair (open and endovascular), femoral-to-popliteal bypass grafting, and carotid endarterectomy. In general, the morbidity and mortality of many vascular operations are not different between a healthy elderly patient and a younger patient, but the elderly are often not diagnosed until late in the disease process, leading to higher risk procedures with higher mortality rates.178 Endovascular interventions have made vascular surgery less invasive; one comparison of aortic endovascular repair to open repair revealed a reduced incidence of perioperative complications compared with open vascular surgery.179 However, long-term follow-up determined that the incidence of cardiac mortality and myocardial infarction was similar.

Cardiac Conduction Procedures

With the significant increase in conduction abnormalities, CAD, and CHF in the elderly, it is logical to anticipate an increased incidence of procedures to treat these abnormalities. In fact, half of all pacemakers implanted in the United States are for patients age 75 years and older.180 Additionally, biventricular pacing for heart failure and cardioverter-defibrillator implantation are also being increasingly used in the care of the elderly, although efficacy and benefit in the elderly are less than those in younger patients.181,182

Thoracic Procedures

The choice to undertake thoracic procedures must be carefully weighed against the risks and benefits in an elderly population. For example, an oncologic indication for a procedure may carry more weight than a quality-of-life indication (eg, surgery for emphysema) in this higher-risk population. A study of 356 patients older than 70 years after lung resection found a 33% to 48% 30-day morbidity and a 4% to 69% 30-day mortality rate.183 Independent predictors for postoperative complications included a low predicted postoperative forced expiratory volume in 1 second (FEV1), concurrent CAD, and extended resection. Others have found that post–lung resection morbidity is predicted by a reduction in the ability to carry out activities of daily living, decreased cognition, and length of surgery.184 Brunelli et al suggested that a simple screening test for surgical fitness is the ability to climb stairs because it was determined that concomitant cardiac disease and a low stair height climbed preoperatively predicted cardiopulmonary complications in the elderly after lung resection.185 The type of procedure contemplated may also affect the decision to offer a surgical intervention, in that a minimally invasive procedure may lead to less immediate morbidity, although the overall long-term mortality may be similar. Esophageal resection has a particularly high morbidity and mortality at baseline, but age as a sole criterion has only a minor influence on overall outcome.186 There appear to be fewer age-related concerns for other types of smaller thoracic procedures such as bronchoscopies, mediastinoscopies, and esophagoscopies.

Transplant Procedures

Organ transplant is also becoming increasingly common among the elderly as the contraindications for transplant with respect to age are being relaxed. An especially interesting program is the Eurotransplant Senior Program that allocates kidneys within a narrow geographic area from donors age 65 years or older to recipients 65 years or older regardless of human leukocyte antigen. Graft and patient survival were not adversely affected, but a 5% to 10% higher rejection rate was noted as compared with younger recipients or younger donors.187 In contrast, survival of elderly heart transplant patients is significantly lower than in young recipients with increased risk of renal failure and malignancy among elderly patients.188 As above, destination a ventricular assist device may be used to complement heart transplant to treat advanced heart failure. Similarly, lung transplants are being offered to patients up to 70 years but must be cautiously allocated to those most likely to benefit.189 One group found that the risk of death increased dramatically after age 70 and concluded that lung transplant should be very limited for those older than 70 years.189

Orthopedic Procedures

As osteoarthritis and rheumatoid arthritis increase with age, so do the procedures to treat these conditions, primarily knee and hip replacements. Furthermore, the high prevalence of skeletal disease, combined with an increased predisposition to fall, leads to a high incidence of fractures (especially of the hips, the vertebrae, and the wrists) in older people who then present for treatment on an emergency basis (Fig. 21-13).

Hip Replacement

Hip replacement and repair of hip fracture are exceedingly common operations in the elderly and aged populations. Unfortunately, hip fracture also carries a very high mortality rate of 20% in the first year after fracture.190 A Cochrane review of the treatment of evidence-based best practices for elderly hip fracture patients revealed that spinal anesthesia, pressure-relieving mattresses, perioperative antibiotics, and deep venous thromboses prophylaxis were beneficial, whereas preoperative traction was not beneficial, and types of surgical management, postoperative wound drainage, and even "multidisciplinary" care lacked sufficient evidence to determine either benefit or harm.191 A large study of 2390 patients older than 60 years with hip fracture found a 9.6% 30-day mortality and a 33% 1-year mortality after hip fracture surgery; preoperative variables that predicted mortality included 3 or more comorbid conditions, preexisting chest infection, and concurrent malignancy.192

Knee Replacement

Total knee replacement (TKR) is primarily a surgery for the elderly, with younger patients less likely to be referred for surgery than older patients.193 As the population ages, TKR is now almost as common as total hip replacement. Long-term results in patients older than 70 years are excellent, but infection and loosening and malpositioning of the implants are common complications.194

Genitourinary Treatment

Elderly men are subject to abnormalities of the urethra primarily related to benign prostatic hypertrophy and prostate cancer; commonly leading to a transurethral prostrate procedure. In contrast, elderly women are prone to bladder and vaginal relaxation with urinary incontinence and prolapse symptoms. Thus many urethral and urethrovaginal procedures are performed on patients older than 65 years. In one study, preexisting cardiovascular disease increased the risk of perioperative complications in elderly women undergoing urogynecologic surgery, but the overall perioperative morbidity rate was low.195 Procedures to treat benign prostatic hypertrophy are commonly performed and usually well tolerated in the elderly. Although age is a prognostic factor for bladder cancer resection, this surgical procedure is also being performed frequently in the elderly patient.196

Abdominal Surgery

Abdominal procedures are undertaken in the elderly for a variety of reasons. As surgical and anesthesia techniques have developed, age is no longer considered a contraindication to an intra-abdominal procedure, in part due to increased use of minimally invasive approaches.197 However, one should be aware of mesenteric ischemia as the cause for abdominal surgery in combination with vascular procedures. This condition typically presents in patients older than 70 years and carries a high incidence of morbidity and mortality due to both the predisposing factors of arteriosclerosis, hypertension, CAD, CHF, diabetes, and obesity but also due to the range and inconsistency of presenting symptoms leading to confusion with other abdominal processes.198

Eye Surgery

Visual impairment conditions increase with age, as do corrective surgical procedures to restore sight; elderly patients represent the majority of the surgical population scheduled for ophthalmologic surgery.199 Eye surgery is usually minimally invasive and performed as day-case surgery despite the high comorbidity of these patients.

Overall Surgical Risk

Overall surgical risk is related to physiologic organ system age, comorbid diseases, and the risks of the procedure to be undertaken. In general, an otherwise healthy elderly patient can expect a good outcome with continued quality of life. However, there are known overall risks for surgery in the elderly. Emergency procedures have especially high mortality in the elderly, in part because they take longer to exhibit symptoms and thus present with more advanced diseases, such as perforation or necrosis.200 An example is a study of 48-hour emergency surgery mortality rates in 795 patients in which patients older than 90 years had a mortality of 7.8% as compared with a 0.6% for age-matched patients undergoing elective surgery.201

The type and number of coexisting diseases are exceedingly important because it has been proposed that the effects from coexisting disease outweigh the effects of age alone on anesthesia outcome.169 When age and severity of illness are compared, the number of coexisting diseases is more significant. Additionally, the albumin level may serve as a marker for preoperative health status of the elderly patient because albumin level has been linked to perioperative mortality.202

Of elderly patients undergoing surgery, 10% to 40% develop a postoperative complication that can lead to serious adverse events.203 According to a recent study, even seemingly mild initial complications may profoundly alter postoperative prognosis, beginning a cascade of other complications that result in death.203 Silber et al examined Pennsylvania Medicare claims and determined that the odds of an elderly patient dying within 60 days after surgery increased 3.4-fold in patients with complications compared with those without complications.203 Certain complications increased the risk substantially, such as respiratory compromise, associated with a 7.2-fold increase in the risk of dying, and CHF, resulting in a 5-fold risk in the odds of dying compared with patients without any perioperative complications.

One must consider, however, that advances in surgical and anesthetic techniques may allow the stabilization of an elderly patient with an emergent condition. For example, a minimally invasive emergency procedure performed with a regional anesthetic may allow stabilization of an elderly patient, thus affording the opportunity for full resuscitation and optimization before a definitive surgical procedure.204

Altered Perioperative Mental Status and Cognitive Dysfunction

Perioperative delirium is common in high-risk surgery and associated with age, education, preoperative cognitive functioning, preexisting medical conditions, and postoperative complications. However, the pathophysiology is poorly understood. As well as being linked to narcotics, sedatives, and anticholinergics, delirium is associated with urinary tract infection, pneumonia, hypoxia or hypercarbia, fever, blood loss, and electrolyte disturbances. For example, 102 patients between 41 and 88 years of age underwent elective open abdominal aortic aneurysm surgery. Delirium occurred in 33% of the patients during the first 6 days after surgery. With multivariate analysis, the most powerful preoperative predictors of delirium were number of pack-years smoked, mental status scores, and number of perioperative psychoactive medications.205 Longer duration of delirium was related to lower education, preoperative depression, and greater preoperative psychoactive medication use. Unrelated variables were characteristics of the surgery and hospital stay.

Persistent postoperative cognitive dysfunction is also a common problem after surgical procedures, estimated by some to be as high as 14% in patients older than 70 years.206 Monk et al further evaluated 1064 patients before, just after, and 3 months after noncardiac surgery.160 They found at 3 months, young and middle-age patients had similar incidences of cognitive dysfunction (5.7%) but that elderly patients still had significantly more dysfunction at 12%. The risk factors identified were similar to those for postoperative delirium and included increased age, lower educational level, and a history of a prior cerebrovascular accident without residual impairment. Persistent postoperative cognitive dysfunction is important because patients were both more likely to die within 3 months of surgery and in the first year after surgery (p = 0.02).160

Given the devastating consequences of postoperative cognitive dysfunction in the elderly, the role of anesthetic choice has been investigated. Forty-seven patients older than 60 years who were undergoing major surgery were randomly allocated to receive either regional or general anesthesia. Overall, elderly patients subjected to general anesthesia displayed more frequent cognitive impairment during the immediate postoperative period in comparison with those who received a regional technique.207

However, several studies have failed to demonstrate any long-term differences in postoperative cognitive function between general and regional anesthesia. Williams-Russo et al examined 262 patients older than 40 who were undergoing total knee arthroplasty, randomly assigned to either epidural or general anesthesia.208 No differences were found between the patients for either cognitive or cardiovascular outcome. Rather, at 1 week postoperatively, both anesthetic groups had significant decreases from their preoperative neurocognitive test scores. At 6 months postoperatively, both groups improved, but the incidence of long-term postoperative cognitive deficit remained at 5% regardless of anesthesia group. Rasmussen and colleagues also examined patients older than 60 years randomly allocated to general or regional anesthesia for major noncardiac surgery.209 They demonstrated that a substantial proportion of patients experienced postoperative cognitive dysfunction at 1 week and 3 months postsurgery (incidence: 10%-20%). There was no significant difference in the incidence of postoperative cognitive dysfunction between the groups at 3 months after surgery. The authors concluded that the choice of anesthesia should be based on an open discussion of patients' preferences, general postoperative complications, and the experience of the anesthetist.

Pain Management

It is generally supported in the literature that the elderly have unique needs for analgesia compared with younger patients, including the problem of increased sensitivity to opioids.210 However, this should not be interpreted to mean that elderly patients do not need pain medication because some have withheld analgesics for fear of prolonged action or increased side effects.211 To care for the elderly patient in pain, one must also consider the coexisting diseases and their effects on the distribution of analgesics, elimination of analgesics, and the potential for exacerbated or unique side effects from analgesic medications in the elderly. Furthermore, the high incidence of postoperative confusion, delirium, or altered mental status may complicate the assessment and communication of postoperative pain. Consideration should be given to the use of nonopioid analgesics, reduced doses of opioid analgesics, and alternative routes of analgesic administration. One solution is to use regional anesthetic techniques with local anesthetics so that opioids are avoided.

Type of Anesthetic

Multiple studies have demonstrated that the type of anesthesia (general vs regional anesthesia) has no substantial effect on perioperative morbidity, but some claim differences in perioperative morbidity.212,213 However, it intuitively makes sense that elderly patients benefit from an anesthesia technique that allows for minimal cognitive depression with excellent postoperative pain control. It is essential to recognize that many factors influence the outcome; the quality of the anesthetic administered rather than the type of anesthetic is most important.212

Quality of Care

We know that improved quality of care (QOC) received by patients is strongly associated with better survival among community-dwelling vulnerable older adults.214 QOC begins with adequate information being obtained from a patient and related to a patient about proposed surgical interventions. An interesting challenge, however, is the finding that there is a strong negative correlation with patient's age and the desire for extensive information about medical care.215 This may mean that QOC must include family members as well as the elderly individual both for obtaining and relating medical information. Perioperative QOC in elderly patients is also of great importance because of the increasing number of older adults undergoing operations.216 QOC indicators have been developed in 7 domains: comorbidity assessment (cardiopulmonary disease), elderly issues (cognition), medication use (polypharmacy), patient-to-provider discussions (life-sustaining preferences), intraoperative care (preventing hypothermia), postoperative management (preventing delirium), and discharge planning (home health care), with most indicators rated addressing processes of care not routinely performed in younger surgical populations.216 However, to address these varied goals, interdisciplinary team care has been applied successfully in hospital, outpatient, home, and nursing home settings.217 Optimal outcomes are achieved in the elderly patient when clinical care is multidisciplinary and integrated beginning from preoperative assessment to supportive care after discharge.218

The elderly are the fastest-growing segment of the world's population and have unique medical and surgical needs. Decrements in organ function decline combined with increases in organ system disease lead to challenges in surgical and anesthetic care. Assessment of comorbid conditions, nutritional status, and physiologic reserve when planning the most efficacious approach to surgical care can lead to excellent outcomes from a variety of procedures in most elderly and aged patients.

Acknowledgment: Many thanks to Terri Monk, MD, Professor of Anesthesiology at the Durham Veteran's Administration Medical Center in North Carolina, for manuscript review, collaborations, guidance, and her excellent work in geriatric medicine.

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