Care of the older patient

Published on 20/03/2015 by admin

Filed under Critical Care Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1607 times

50 Care of the older patient

Definitions

Activities of Daily Living:  Daily self-care activities, including bathing, eating, dressing, toileting, and grooming.

Cognitive Impairment:  Reduction in mental functioning that results in cognitive changes, including short-term memory loss and impaired judgment and thinking.

Cultural Competence:  The ability to provide culturally relevant and appropriate care to persons with diverse values, beliefs, and behaviors.

Dementia:  A loss of brain function that occurs with certain a group of diseases. It affects memory, thinking, language, judgment, and behavior. The most common form of dementia is Alzheimer disease.

Geriatrics:  Medical aspect of gerontology in the treatment of acute and chronic conditions in older adults (i.e., a person 65 years of age or older).

Gerontology:  The scientific study of age, aging, and the aged using a lifespan, biopsychosocial approach.

Health:  A state of physical, mental, and social well-being.

Instrumental Activities of Daily Living:  The activities performed by people living independently, including meal preparation, money management, shopping, and taking medications.

Person-Centered Care:  Focuses on individual care needs by understanding how the individual experiences his or her situation in order to most effectively address needs and desired outcomes.

Presbycusis:  Age-associated hearing changes or the slow loss of hearing as people get older.

Presbyopia:  Age-associated visual changes of diminished ability to focus on near objects.

The world’s population is aging at a rapid pace. The current population of adults older than 65 years constitutes 34 million people, or approximately 13% of the population. Projections suggest that by 2030, 69 million individuals will be older than 65 years, or approximately 19% of the population.1 This trend represents two important phenomena: the increase in life expectancy and the aging of the baby boomers (those born between 1946 and 1964) who began to turn 65 in 2011. Older adults are not only living longer; they are doing so free of disease and disability. According to “compression of morbidity theory,” the limit to life span may be stretched significantly with a concurrent delay in the onset of chronic conditions.2 This stretching of the lifespan would result in a population living longer and healthier than any generation to date.

The World Health Organization defines health as a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.3 In this view, older adults may then perceive themselves as healthy despite physical limitations or disease. It is essential in caring for the older patient to recognize overall health from physiologic, psychological, and social perspectives. In assessing an older adult’s health, an appropriate delineation is between an individual’s chronological age versus their functional age. Some individuals who are more judicious in using preventive health measures and who maintain more active lifestyles may have little decline or age-related comorbidities, reflecting greater functioning relative to chronologic age, whereas others may have multiple comorbidities, perhaps at an even earlier age, reflecting functional limitations relative to age. Gerontologists often use the distinctions young-old, old-old, and oldest-old to differentiate between older adults. In terms of functional capacity, gerontologists also describe aging in terms of primary, secondary, and tertiary aging.4 Primary aging represents aging free of disability and disease. Secondary aging encompasses developmental changes affected by lifestyle, disease, or factors that are not inevitable processes of biologic aging. Tertiary aging is rapid loss and decline experienced at the end of life. Differentiation of age and functional capacity is essential to focus attention on the diversity of this population and establish some markers that are helpful in meeting the individual needs of older adults.

Many different chronologic markers are used for governmental determinations and legal purposes (i.e., 40 years of age for age discrimination determination, 50 years of age for AARP membership, and 65 plus years of age for Social Security). As a result, no one definition of old-age, elderly, or older adult is accepted. Because no biomarkers exist, a definition of when old age begins is difficult because individuals age at different rates than is reflected simply by chronologic age. The growing complexity and diversity of the aging population mandates a holistic interprofessional biopsychosocial approach to care to move beyond a simplistic chronologic marker of age toward a more accurate functional assessment.

Care of the older adult patient is particularly important in the postanesthesia care unit because of the normal physiologic changes that occur with aging and may be compounded by multiple comorbid conditions. With advancing age, the potential risks of complications from surgical procedures increases, because of the potential for multiple comorbidity. Morbidity and mortality are at least fourfold more likely in older adults and twentyfold more likely in emergency procedures.5 These conditions include congestive heart failure, insufficient oxygenation of the blood, improper elimination of carbon dioxide, fluid and electrolyte imbalance, diabetes and the associated complications, and drug toxicity.

Advances in anesthetic care have resulted in a substantial reduction in perioperative morbidity and mortality in the aging population.6 Successful anesthesia care of the older adult patient is highly dependent on the knowledge of the changes associated with aging and the effects of anesthesia on the older patient. Therefore, the focus of this chapter is primarily on the normal aging changes that take place in addition to the disease states associated with aging and their translation to functional status, especially of the cardiovascular system. It is essential to keep in mind throughout this chapter that the rate at which each individual and organ system age is highly individualistic. This phenomenon is referred to as the individuation of aging.7 Individual genes, hormonal balance, diet, medications, environmental exposure, and emotional stress and burden are all factors that influence individual biological aging.

The aging body: an overview

Cardiovascular system

Cardiovascular health is essential to the overall well-being of the older adult. Healthy cardiovascular functioning can be maintained across the lifespan, and disease can be prevented through healthy lifestyle choices and preventive care; however, heart disease remains the leading cause of death for both males and females.8 Of all of the body systems, the cardiovascular system exerts the most influence on anesthesia and general health outcomes.8 Annually, more than 1 million surgeries are complicated by adverse cardiac outcomes, such as postsurgical myocardial infarction or death from cardiac disease.9 This risk can be reduced with a thorough preoperative interview and assessment that examines functional capacity and existing comorbidities and the current treatment regime.8

Functional capacity

The assessment of functional capacity reflects the ability to perform activities of daily living that require sustained aerobic metabolism.10 Exercise tolerance in daily life is the best indicator of the quality of biologic age. It is also one of the most important predictors of perioperative outcomes in older adult patients.11,12 Poor exercise tolerance reflects low functional capacity and greater severity of disease. Functional status is usually reflected in metabolic equivalent (MET) levels. One MET corresponds to a resting oxygen consumption of 3.5 mL/kg/min. MET scores are multiples of resting metabolism, which are used as a point of reference to describe the oxygen demands of any activity.13 Box 50-1 provides examples of MET ratings of activities. Functional status can be ascertained during the preoperative screening. Questions addressing daily activities and assessing lifestyle habits, such as house cleaning, vacuuming, walking, and stair climbing, and any participation in regular exercise should provide adequate information for a subjective assessment of the patient’s functional status.14 Objective assessment can be made via exercise testing. Patients who are unable to regularly meet a 4 MET demand have an increased perioperative cardiac risk.15

MET, Metabolic equivalent.

Adapted from Hlatky MA, et al: A brief self-administered questionnaire to determine functional capacity, Am J Cardiol 64:651–654, 1989; Fletcher GF, et al: Exercise standards: a statement for healthcare professionals from the American Heart Association, Circulation 104:1694–1740, 2001.

Structural changes

There are several structural changes frequently seen with advancing or older age that occur within the cardiovascular system. Changes of the arteries include dilation of the large arteries accompanied by thickening of the arterial walls and changes in wall matrix. An increase in elastin and collagen tissues in the heart and arteries can cause arterial wall thickening and an increase in smooth muscle tone.1619 Increased vascular stiffness leads to elevated systolic arterial pressure and pulse wave velocity, early reflected pulse pressure waves, and late peak systolic pressure, which trigger a series of cardiac adjustments. A resultant augmenting of aortic impedance and cardiac mechanical load may be seen.

Clinically elevated left ventricular afterload causes an increase in myocyte size and thickening of the left ventricular wall.18 When combined with augmentation of aortic impedance, elevated afterload prolongs myocardial contraction. This adaptive measure preserves cardiac function by lengthening the amount of time available for the heart to eject blood into stiffened vasculature. The resultant prolonged myocardial contraction delays ventricular relaxation time, which manifests as a decrease in early ventricular filling.1923

Between the ages of 20 and 80 years, the rate of early diastolic filling decreases by 50%.24 This decrease may be the result of a prolonged isovolumetric relaxation time between aortic valve closure and mitral valve opening. With aging, alterations in calcium release from the myoplasm to the sarcoplasmic reticulum may contribute to the changes in early diastolic filling.16,23

For maintenance of stroke volume, end diastolic filling is increased.16 The effectiveness of this strategy is dependent on the atrial contribution to end diastolic filling; therefore left atrial size increases.20 Enlargement of the atria raises the likelihood of atrial fibrillation among elders, thus underscoring the importance of stable hemodynamics to ensure normal sinus rhythm.

Gender differences may be found in certain age-related changes in cardiac function.16 Men seem to have different compensatory mechanisms than women. To maintain stroke volume in the presence of the age-associated decrease in heart rate, men have an increase in left ventricle end-systolic volume and left ventricle end-diastolic volume. This mechanism preserves cardiac output in aging men, whereas a 15% decrease is seen in cardiac output in women. Table 50-1 summarizes cardiac changes in response to exercise that occur with age.25

Table 50-1 Changes in Cardiovascular Response to Exercise with Comparison of 20 and 80 Years of Age

CARDIOVASCULAR PHYSIOLOGY PEAK RESPONSE AT AGE 20 YEARS CHANGE IN PEAK RESPONSE BETWEEN 20 AND 80 YEARS
LV end-diastolic volume ↔,↓ ↑30% males; ↔ females
LV end-systolic volume ↓100%
Ejection fraction ↓15%
Stroke volume
Heart rate ↓25%
Cardiac output ↓25%
Stroke work ↑15% males; ↔ females
SVR ↑30%
Oxygen consumption ↑50%
Plasma catecholamines
Myocardial contractility ↓60%
Beta-adrenergic stimulation Fully functional

LV, Left ventricular; ↔, no change; ↑, increase; ↓, decrease; SVR, systemic vascular resistance.

Adapted from Eagle KA: Perioperative cardiac assessment for noncardiac surgery: eight steps to the best possible outcome, Circulation 107:2771–2774, 2003.

The most clinically relevant age-related changes in cardiovascular function are increased myocardial stiffness and all of the subsequent compensatory actions and blunted beta-adrenergic responses. During increased oxygen demand, the most relevant changes in the older patient are autonomic reflex dysfunction and beta-adrenoreceptor responsiveness. See Table 50-1 for cardiovascular age-related changes to upright peak exercise.

In addition, the type of surgery coupled with the degree of hemodynamic stress incurred during the surgery are the major determining factors of perioperative risk.11,12 Emergency surgeries are particularly high risk, especially in older patients. Other high-risk surgeries include vascular, cardiac, abdominal, and thoracic surgeries.26 Box 50-3 categorizes surgery-specific risk according to the incidence rate of cardiac death and nonfatal myocardial infarction for noncardiac surgical procedures.

Heart

It is difficult to determine which changes in the cardiovascular and circulatory systems represent normal aging and which are disease states. Current research suggests that overall heart size in healthy older adults does not change significantly with age.27 However, there are many cellular and biochemical changes associated with older age.16,24,28 These changes include altered growth-controlling factors, impaired excitation-contraction coupling, impaired calcium homeostasis, increased myocyte apoptosis, and an increase in atrial natriuretic peptide secretion.

As a result of these age-related biochemical and molecular changes, a number of morphologic changes manifest as changes in cardiac function (Table 50-2). It is important to note that cardiac senescence can result in a number of functional impairments. These impairments can include decreased mechanical and contractile efficiency, prolongation of the contraction phase, stiffening of myocardial cells, stiffening of valves and mural connective tissue, decreased number of myocytes, increased myocyte size, increased rate of myocyte apoptosis, and a blunted beta-adrenoceptor–mediated inotropic response.2931

Table 50-2 Changes in Cardiovascular Physiology in Healthy Individuals Between Ages 20 and 80 Years*

LV end-diastolic volume ↑20% males; ↔ females
LV end-systolic volume ↑20% males; ↔ females
Ejection fraction
Stroke volume ↑20% males; ↔ females
Heart rate ↓10%
Cardiac output ↔ males; ↓ 15% females
Stroke work ↑15%
Early diastolic filling rate ↓50%
Systolic arterial pressure ↑15%
Systemic vascular resistance ↔ males; ↓ 45% females

LV, Left ventricular; ↔, no change; ↑, increase; ↓, decrease.

Adapted from Eagle KA: Perioperative cardiac assessment for noncardiac surgery: eight steps to the best possible outcome, Circulation 107:2771–2774, 2003.

There is tremendous variability in both the level and intensity of age-related changes to the heart. In nonstressful conditions, the normal aging heart functions appropriately. Under stress or with damage from disease, the effects of age become more profound and can lead to functional limitations and reduced quality of life for the patient.

Hepatic function

By the time an individual is 80 years old, an approximate 40% reduction in hepatic mass and a 40% decrease in hepatic and splanchnic blood flow are seen. Decrease in the activity of hepatic cholinesterase and microsomal demethylation pathway may also accompany increasing age.34,35 These changes lead to an impaired ability to meet the increased demands of metabolism, biotransformation, and protein synthesis after surgery. Drugs that rely on hepatic metabolism have a prolonged effect for older adults. For prevention of hepatic injury from medication, hypoxia, or transfusion, careful attention to appropriate drug dosage and adequate oxygenation should be made.

Thermoregulation

Temperature regulation is slower with advanced age, with the shivering and sweating responses showing marked reductions.17 As a result, advanced age is considered a predisposing factor for perioperative hypothermia,3639 which can impose increased demands on the cardiovascular system. Specifically, perioperative hypothermia exerts a number of adverse effects, including prolonged drug action,40 negative postoperative oxygen balance,41 immune dysfunction,42 and subsequent increased incidence of wound infection.43 Cardiac changes include a leftward shift of the hemoglobin-oxygen saturation curve, increased vascular resistance, cardiac arrhythmias, and up to a fourfold increase in cardiac output and oxygen consumption associated with rewarming and shivering.42 Special care to maintain normothermia can minimize the risk of postoperative ischemia and angina in older patients.

Sensory system

Although sensory changes are significantly affected by lifestyle, by midlife most individuals experience presbyopia (age-associated vision change) and presbycusis (age-associated hearing change). Being mindful of sensory changes improves the care for patients.

Communication with a person with age-associated hearing loss, or presbycusis, can be improved by:

Communication with a person with age-associated vision loss, or presbyopia, can be improved by:

A person-centered approach and respectful language is foundational to providing quality care and assisting patients to maintain a sense of self. Frequently, ageist stereotypes lead to inaccurate assumptions regarding compliance and performance. Poor cognitive performance once thought to be the result of age-related cognitive decline is now understood to be the result of extraneous variables such as sensory changes, fatigue, low education levels, hypermotivation, and polypharmacy.

The aging mind: an overview

Dementia and delirium

Differentiating dementia, cognitive impairment, and delirium is essential for the anesthesia provider. Whereas true dementias are inherently irreversible, delirium and cognitive decline are potentially reversible if properly diagnosed and treated.

It is well established that dementia is not a normal or inevitable part of the aging process. Although Alzheimer disease (AD) is the most common type of dementia and accounts for 60% to 70% of all dementia, other forms of dementia also affect older adults. For example, vascular dementia, Lewy body dementia, and frontotemporal dementia are also prevalent forms.

The dementias are characterized by a global decline in cognitive function resulting in significant social or functional impairment.44 Dementia seriously affects a person’s ability to perform activities of daily living, including feeding, bathing, and dressing. Initial involvement is in parts of the brain that control thought, memory, and language. Although the exact cause of AD is unknown, autopsies reveal three different types of lesions on patients’ brains: senile plaques, neurofibrillary tangles, and vascular lesions. Senile plaques and vascular lesions contain high levels of beta-amyloid protein. The important consideration from an anesthesia perspective is that the presence of dementia also indicates that the patient has increased metabolic risk and comorbidities that need to be addressed during preanesthesia and perianesthesia phases.

Cognitive impairment refers to cognitive changes including short-term memory loss, confusion, and decreased performance on neuropsychological tests. Symptoms of cognitive impairment are greater than changes caused by normal aging, but are insufficient to meet the criteria for a dementia diagnosis. Delirium is a disorder that disrupts brain functionality. Delirium clinically presents with major behavioral changes not explained by a preexisting dementia.27

Postoperative cognitive decline and delirium are adverse events that occur frequently in older adults.45 One study of delirium in older adult patients found a prevalence of 31.4% at initial assessment and an incidence of 31.1% during the course of hospitalization.44 Postoperative deliriums can be particularly prevalent and problematic for older patients. Preexisting patient factors, medications, and various intraoperative and postoperative causes have been implicated in the development of postoperative delirium.45

There are a number of tools available for assessing and screening for delirium, including the confusion assessment method (CAM), and the delirium rating scale (DRS).46,47 A physical examination, history assessment, and laboratory study are all important tools for identifying possible causes of delirium.

Working with the aging population: essential concepts

Geropharmacology

Older adults living in the community take an average of 2.7 to 4.2 prescription and nonprescription medications.48 Nonprescription medications include both over-the-counter (OTC) drugs as well as dietary supplements. Among prescription medication users, approximately 46% concurrently use OTC drugs and 52% concurrently use dietary supplements.49 Concurrent use of prescription medications, OTCs, and dietary supplements can lead to medication-related adverse events. Medication-related problems have many forms, often as a result of polypharmacy: overuse of medications, inappropriate prescribing, and drug interactions. Hanlon and colleagues48 found that 55% of outpatients were taking drugs with no indication, 33% were taking ineffective drugs, and 17% were taking drugs with therapeutic duplications.50,51 Thirty percent of hospital admissions are linked to medication-related problems; furthermore, medication-related problems are the fifth leading cause of death in the United States.52

Almost one quarter of community-dwelling older adults use medications that should be avoided. The Beers criteria, a list of medications that are usually considered inappropriate when given to elderly people, were created to measure inappropriate prescribing and highlight common drug interactions.53 These criteria are updated regularly and should be a companion when working with older adult patients. For example, long-acting benzodiazepines, dipyridamole, propoxyphene, and amitriptyline were the most frequently inappropriately prescribed medications.51 Table 50-3 illustrates some possible adverse effects or drug interactions that can take place in older patients during the perioperative period. Age-related changes to organ systems affect a drug’s pharmacokinetic and pharmacodynamic properties.

Table 50-3 Adverse Effects or Drug Interactions Associated with the Older Adult Patient

DRUG ADVERSE EFFECT OR DRUG INTERACTION
Antibiotic Prolongation of muscle relaxants
Antidysrhythmic Prolongation of muscle relaxants
Benzodiazepine  
Diazepam Decreased metabolism
Chlordiazepoxide Increased CNS effects
Flurazepam Prolonged drowsiness
Digoxin Decreased renal excretion with increased CNS disorientation, anorexia, nausea, and cardiotoxicity; blood levels twofold to threefold higher in older adult with any given dose
Diuretic Hypokalemia, hypovolemia
Halothane Decreased anesthetic requirement
Lithium Clearance decreased by 65% and effective dose by 30% in comparison with patients at 25 years of age; increased side effects of tremor, diarrhea, and edema
Meperidine Markedly elevated plasma levels and decreased red blood cell and plasma binding of drug; increased incidence rate of nausea, respiratory distress, and hypotension
Methyldopa Enhanced hypotensive effects
Pancuronium Decreased clearance from plasma
Propranolol Plasma level approximately threefold to fourfold higher in elderly because of decreased metabolism; bradycardia, congestive heart failure, bronchospasm, mental confusion, and attenuation of autonomic nervous system activity
Tricyclic antidepressant Increased anticholinergic effects: confusion, agitation, and disorientation; cardiac conduction disturbances; increased anesthetic requirements
Warfarin Enhanced sensitivity

CNS, Central nervous system.

Adapted from Krechel S, editor: Anesthesia and the geriatric patient, New York, 1984, Grune & Stratton; Miller R, editor: Anesthesia, ed 5, New York, 2000, Churchill Livingstone.

Pharmacokinetics refers to the time it takes for the drug to be liberated, absorbed, distributed, metabolized, and excreted. Drug distribution is altered by the age-related decrease in total body water and lean mass, increase in total body fat, decrease in serum albumin, decrease in cardiac output, reduction in blood volume, and increase in α1-acid glycoprotein.54 Injection of medication into a contracted blood volume produces a higher plasma concentration of drug. High protein–bound drugs may have an exaggerated clinical effect (e.g., lidocaine, propranolol, thiopental, etomidate, profol, alfentanil) because of a higher level of unbound (free) drug. Decreased distribution of water-soluble drugs can cause an adverse reaction because of the initial high plasma concentrations. Conversely, increased distribution of fat-soluble drugs can prolong the action of that medication (e.g., diazepam, midazolam).54

Pharmacodynamics is the ability of the drug to react with a specific receptor and to translate that effect on the receptor into a physiologic response. This reaction can render older adults more sensitive to a given concentration of most drugs; however, the opposite is true in regard to beta-adrenoreceptor antagonist and agonist and to digoxin. A higher incidence rate of hyperkalemia, renal failure, and death from gastrointestinal bleeding is associated with the use of nonsteroidal antiinflammatory drugs.18,54

In the assessment of the older adult patient, the informed clinician must consider changes in cardiovascular, renal, hepatic, and respiratory function; the compensatory mechanisms; and coexisting comorbid conditions. As a result of marked heterogeneity of drug response in older adult patients, no strict age rules can be applied across the entire older adult population.25

Person-centered care and cultural competence

Adults 65 years of age and older compose a culturally diverse and heterogeneous population. Although cohort effects (e.g., being raised during the Great Depression) result in some similarities in terms of preferences from living within one historic time period, many years of lived experience lead to enormous interindividual diversity.

Person-centered care necessitates taking the time to know the patient’s personal preferences, goals, and priorities to provide the highest quality care. A person-centered approach views the patient as the center of defining what is most important to effective delivery of his or her care and care outcomes. An individuals’ life experience affects their personal health beliefs, which results in a wide variety of understanding, preferences, and knowledge regarding care provision and medical practice. Assurance of understanding is essential to quality patient care and is at the foundation of person-centered care. Contrary to popular belief, older adults are among the most compliant in regard to care planning. Most frequently, poor compliance is the result of external barriers (e.g., income restrictions) and lack of understanding from poor communication.

The population of older adults includes increasing numbers of individuals from diverse ethnic groups and backgrounds. This diversity presents practitioners with both opportunities and challenges in providing culturally relevant care to the individual. Cultural competency challenges us to understand how people of different cultural backgrounds might approach health, health care, and treatment options. Cultural competence also means having the ability to provide care to persons with diverse values, beliefs, and behaviors and to tailor care delivery to their social, cultural, and linguistic needs. Being culturally competent entails being aware and accepting of differences, thinking about how one’s own culture influences oneself, and being aware of when cultures interact, what stereotypes are at play, and what patterns of communication are necessary to avoid misinterpretations or misjudgments.

References

1. U.S. Census Bureau of Census: Current population survey. Washington, DC: U.S. Government Printing Office; 2003.

2. Fries JF. Aging, natural death and the compression of morbidity. N Engl J Med. 1980;303:130–135.

3. World Health Organization: Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference. available at: www.who.int/about/definition/en/print.html, August 13, 2011. Accessed

4. Birren JE, Cunningham WR. Research on the psychology of aging: principles, concepts, and theory. Birren JE, Schaie KW. The handbook of the psychology of aging. New York: Van Nostrand Reinhold Co, Inc, 1985.

5. Bailes BK. Perioperative care of the elderly surgical patient. AORN J. 2000;72(2):186–206.

6. Bekker A, et al. Does mild cognitive impairment increase the risk of developing postoperative cognitive dysfunction. Am J Surgery. 2010;199:782–788.

7. Henderson JL. Thresholds of initiation. Middletown, Connecticut: Wesleyan University Press; 1967.

8. Centers for Disease Control: Trends in health and aging: aging and chronic disease statistics branch. (website). www.cdc.gov/index.htm, August 2, 2011. Accessed

9. Maddox TM. Preoperative cardiac evaluation for noncardiac surgery. Mt Sinai J Med. 2005;72(3):185–192.

10. Arena R, et al. Assessment of functional capacity in clinical and research settings. Circulation. 2007;116(3):329–343.

11. Eagle KA, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for non-cardiac surgery: executive summarya report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation.2002;94:1052–1064.

12. Fleisher LA. Preoperative cardiac evaluation. Anesthesiol Clin North Am. 2004;22:59–75.

13. McArdle WD, et al. Exercise physiology: energy, nutrition and human performance. ed 3. Philadelphia: Lea & Febiger; 1991.

14. Hlatky MA, et al. A brief self-administered questionnaire to determine functional capacity. Am J Cardiol. 1989;64:651–654.

15. Fletcher GF, et al. Exercise standards: a statement for healthcare professionals from the American Heart Association. Circulation.2001;104:1694–1740.

16. Lakatta EG. Cardiovascular aging research: the next horizons. J Am Geriatic Soc.1999;47:613–667.

17. Lakatta EG. Aging effects on the vasculature in health: risk factors for cardiovascular disease. Am J Geriatr Cardiol.1994;3:11–17.

18. Lakatta EG, et al. Heart disease: a textbook of cardiovascular medicine. ed 5. Philadelphia: Saunders; 1997.

19. Wei JY. Age and the cardiovascular system. N Engl J Med. 1992;327:1735–1739.

20. Klein AL, et al. Effects of age and physiologic variables on right ventricular filling dynamics in normal subjects. Am J Cardiol. 1999;84:440–448.

21. Gardin JM, et al. Left ventricular diastolic filling in the elderly: the cardiovascular health study. Am J Cardiol.1998;82:345–351.

22. Palka P, et al. The effect of long-term training on age-related left ventricular changes by Doppler myocardial velocity gradient. Am J Cardiol. 1999;84:1061–1067.

23. Schulman SP, et al. Age-related decline in left ventricular filling at rest and exercise. Am J Physiol. 1992;263:H1932–H1938.

24. Lakatta EG. Changes in cardiovascular function with aging. Eur Heart J. 1990;II(suppl C):22–29.

25. Priebe HJ. The aged cardiovascular risk patient. Br J Anesth. 2000;85:763–778.

26. Eagle KA. Perioperative cardiac assessment for noncardiac surgery: eight steps to the best possible outcome. Circulation.2003;107:2771–2774.

27. Saxon SV, et al. Physical change and aging: a guide for the helping professions. ed 5. New York: Springer; 2010.

28. Folkow B, Svanborg A. Physiology of cardiovascular aging. Physiol Rev. 1993;73:725–764.

29. Lakatta EG. Cardiovascular mechanisms in advanced age. Physiol Rev. 1993;73:413–467.

30. Olivetti G, et al. Cardiomyopathy of the aging human heart: myocyte loss and reactive cellular hypertrophy. Circ Res.1991;68:1560–1568.

31. Yang B, et al. Age-related left ventricular function in the mouse: analysis based on in vivo pressure-volume relationships. Am J Physiol.1999;46:HI906–HI913.

32. Carpo RO, Campbell EJ. Aging of the respiratory system. Fishman AP, ed. Pulmonary diseases and disorders. New York: McGraw-Hill; 1998.

33. Shannon RP, et al. The influence of age on water balance in man. Semin Nephrol. 1984;4:346–352.

34. Shannon RP, et al. The effect of age and sodium depletion on cardiovascular response to orthostasis. Hypertension. 1986;8:438–443.

35. Kampnann JP, et al. Effect of age on liver function. Geriatrics. 1975;30:91–95.

36. Woodhouse KW, et al. The effect of age on pathways of drug metabolism in human liver. Age Ageing. 1984;13:328–334.

37. Freidl LP, et al. Risk factors for 5-year mortality in older adults: the cardiovascular health study. JAMA.1998;279:585–592.

38. Kurz A, et al. The threshold for thermoregulatory vasoconstriction during nitrous oxide/isoflurane anesthesia is lower in the elderly than in young patients. Anesthesiology. 1993;79:465–469.

39. Vaughan MS, et al. Postoperative hypothermia in adults: relationship with age anesthesia, and shivering to re-warming. Anesth Ana.1981;60:746–751.

40. Heier T, et al. Mild intraoperative hypothermia increases duration of action and spontaneous recovery of verconium blockade during nitrous oxide-isoflurane anesthesia in humans. Anesthesiology. 1991;74:815–819.

41. Carli R, et al. Effect of preoperative normothermia on post operative protein metabolism in elderly patients undergoing hip arthroplasty. Br J Anesth. 1989;63:276–282.

42. Valeri RC, et al. Hypothermia-induced reversible platelet dysfunction. Ann Surg. 1987;205:175–181.

43. Kurz A, et al. The study of wound infection and temperature group: perioperative normothermia to reduce the incidence of surgical wound infection and shorten hospitalization. N Engl J Med.1996;334:1029–1035.

44. Ajilore OA, Kumar A. Delirum and dementia. Journal of Lifelong Learning in Psychiatry. 2004;2:211–220.

45. Fong HK, et al. The role of postoperative analgesia in delirium and cognitive decline in elderly patients: A systematic review. Anesth Analg.2006;102:1255–1266.

46. Trzepacz PT, et al. A symptom scale for delirium. Psychiatry Res. 1988;23:89–97.

47. Inouye SK, et al. Clarifying confusion: the confusion assessment method. Ann Intern Med.1990;113:941–948.

48. Hanlon JT, et al. Suboptimal prescribing in older inpatients and older outpatients. JAGS. 2001;4:200–209.

49. Qato DM, et al. Use of prescription and over-the-counter medications and dietary supplements among older adults in the United States. JAMA. 2008;300(24):2867–2878.

50. Fick DM, et al. Updating the Beers criteria for potentially inappropriate medications in older adults: results of a U.S. consensus panel of experts. Arch Intern Med.2003;163:2716–2724.

51. Aparasu RR, Mort JR. Inappropriate prescribing for the elderly: Beers criteria-based review. Ann Pharomacother.2000;34:338–346.

52. Simon SR, Gurwitz JH. Drug therapy in the elderly: improving quality and access. Clinical Pharmacol.2003;73:387–393.

53. Beers MH. Explicit criteria for determining potentially inappropriate medication use by the elderly: an update. Arch Intern Med.1997;157:1531–1536.

54. Montamat SC, et al. Management of drug therapy in the elderly. N Engl J Med. 1989;304:405–412.