Nagelhout Chapter 54- Lesson 3

• By 2050, the number of people 85 years and older is expected to triple, making the U.S. the largest population of the oldest old among developed countries
• Older adults will become more racially and ethnically diverse
• Older adults have higher rates of inpatient and outpatient surgical procedures
• Surgical services and hospitalizations for older adults will increase as the population ages
• Anesthesia practitioners need to adjust their approach to anesthetic management for geriatric patients
• "Older adults" or "elderly" are defined as persons 65 years or older

Preoperative Assessment

• Preoperative assessment of older adults requires special considerations
• The elderly are prone to decline in baseline functions, age-related comorbid diseases, and increased ASA physical status
• Older adults are at greater risk for perioperative complications, including morbidity and mortality
• Postoperative complications in the elderly include cardiac, pulmonary, and neurologic issues
• Factors that influence outcomes in older adults include emergency surgery, comorbidities, and surgical procedure
• The older adult surgical patient requires a comprehensive preoperative evaluation including assessing operative risk and physical status
• Risk assessment and stratification are important for multidisciplinary team approach and informed consent
• Identifying perioperative risk is part of the preoperative assessment and is preferably performed prior to the day of surgery
• The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) and the American Geriatrics Society (AGS) developed Best Practice Guidelines for Optimal Preoperative Assessment
• Specific assessment categories are recommended to guide perioperative management

Age-Related Physiologic Changes

• Aging is a time-related occurrence during the organism's life cycle
• Defined as a time-dependent biologic continuum that begins with birth and persists with gradual impairments of organ subsystems
• By age 30, most age-related physiologic functions in humans have peaked and decline thereafter
• Chronologic age (age in years since birth) and biologic age (functional status) differ
• Chronologic age alone is no longer a reliable indicator of morbidity or mortality
• Functional status that remains with increasing age varies

Cardiovascular System

• Age-related changes in the cardiovascular system involve structural and functional changes in the heart, vessels, and autonomic nervous system
• In the older adult, the heart and vascular system is less compliant
• Faster propagation of the pulse pressure waveform, an increase in afterload, and an increase in systolic blood pressure
• Leads to ventricular thickening (hypertrophy) and prolonged ejection times
• Combination of ventricular hypertrophy and slower myocardial relaxation often results in late diastolic filling and diastolic dysfunction
• Atrial contraction becomes important in maintaining adequate ventricular filling
• Elderly exhibit decreased end-organ adrenergic responsiveness even with higher amounts of circulating catecholamines
• Reduced capacity to increase heart rate in response to hypotension, hypovolemia, and hypoxia
• Prolonged circulation time causes a faster induction time with inhalation agents but delays the onset of intravenous drugs
• Calcification of the conducting system with loss of sinoatrial node cells predisposes the elderly to atrial fibrillation, sick sinus syndrome, and arrhythmias
• Higher proportion of this population may have, or require permanent pacemakers and/or automatic internal defibrillators
• Calcification may be present in the valves (primarily aortic and mitral), predisposing elderly patients to valvular stenosis or regurgitation
• Hypertension is a risk factor for perioperative complications
• Decreased vein compliance can lead to decreased venous return and reduce atrial filling
• Decreased sensitivity of baroreceptors results in increased episodes of hypotension
• Changes in the heart's regulation of calcium, which causes the myocardium to generate force over a longer period after excitation, and prolongs the systolic phase of the cardiac cycle
• Myocardium has decreased sensitivity to B-adrenergic modulation
• Older adults may have higher blood pressures caused by increased peripheral vascular resistance, decreased arterial elasticity, and cardiac workload; decreased cardiac output and stroke volume
• Decreased conduction velocity and reduction in venous blood flow
• Decreased cardiac reserve and decreased maximum heart rate adversely affects the compensatory mechanisms of the older adult under the stress of anesthesia and surgery
• Elderly are significantly more vulnerable to adverse perioperative cardiac events
• Myocardial infarction is the most common cardiac complication and the leading cause of death in the postoperative period
• Noncardiac surgery requires cardiac assessment of the cardiovascular system in older adults is essential
• Guidelines according to the American College of Cardiology/American Heart Association (ACC/AHA)
• Risk stratification tools include measuring functional capacity via metabolic equivalents (METs) and the perioperative cardiac risk calculator

Respiratory System

• Age-related alterations of the respiratory system impact oxygenation in the elderly patient
• Older patients develop calcifications of the chest wall, intervertebral joints, and intercostal joints
• Factors contribute to a decrease in chest wall compliance
• Diaphragm flattens, a loss of intervertebral disc height, and changes in spinal lordosis, which may further diminish chest wall compliance
• Generally, loss of elastic tissue recoil of the lung, results in reduced functional alveolar surface area available for gas exchange
• Increase in lung compliance impairs the matching of ventilation and perfusion, increases physiologic shunt, and results in the reduction of oxygen exchange at the alveolar level
• Increase in lung compliance causes small airway diameter to narrow, and eventually increases the closing volume
• Decrease in vital capacity, an increase in residual volume, FRC volume, with decreases in inspiratory reserve volume and expiratory reserve volume
• Decline in resting arterial oxygen tension (PaO2)
• Regulation of breathing affected with aging

Renal Function

• Age-related changes in renal function are significant because of the many roles of the kidneys
• Older adults have a baseline decrement in renal function relative to their younger counterparts
• Renal function changes are characterized by a progressive atrophy of kidney parenchymal tissues, deterioration of renal vascular structures, decreased renal blood flow, and an overall decrease in renal mass
• Cumulative effect is a decrease in the glomerular filtration rate (GFR), decreased renal drug clearance and decreased renal blood flow from age 20 years to age 90 years
• Kidneys play vital role in maintenance of fluid and electrolyte balance
• Contribution to acid-base balance is important

Hepatic Function

• Aging adult liver decreases in mass by approximately 20% to 40%
• Age related functional hepatic changes primarily affect drug metabolism and protein binding
• Changes cause decreased metabolism, prolonged half-life, and either increased or decreased distribution of medications
• Decline in functional hepatic reserve in the elderly patient

Endocrine System

• The decline in number and function of the pancreatic islet beta cells results in decreased insulin secretion
• Insulin resistance occurs peripherally, which contributes to increased hepatic production of glucose and impaired breakdown of fats and proteins
• Diabetes major risk factor for cardiovascular disease

Body Composition and Thermoregulation

• Body composition and metabolism changes occur with the aging adult
• Decrease in the basal metabolic rate (BMR) as a result of decreased physical activity and/or decreases in serum testosterone and growth hormone levels
• Total body water loss is mostly intracellular and somewhat in the extracellular compartment

Central Nervous System

• Age-related physiologic changes characterized by a progressive loss of neurons and neuronal substance, decrease in neurotransmitter activity, and decreased brain volume
• Changes affect regulation of brain function
• Result in mood, memory, and motor function changes
• Cellular processes participate in neurotransmitter synthesis and release
• Processes such as intra-neuronal signal transduction and the second messenger system, may be altered
• Increase the risk for postoperative delirium (POD) or cognitive dysfunction

Cognitive Ability/Capability and Decision Making

• There is an increasing rate of neurocognitive disorders in the older adult
• The ACS NSQIP/AGS recommends to assess the cognitive ability, capacity for decision making, and risk factors for POD
• Several screening tools are available, but the Mini-Cog recommended as can be rapidly administered, is highly sensitive and specific for dementia, and is unbiased by variances in education or language
• Important to determine decision making capacity for informed surgical concent
• the surgeon identifies the decision-making ability of the patient during the informed consent
• Responsibilities to ensure the patient is able to make sound decisions

Frailty

• Frailty is a perioperative risk factor for complications and mortality
• Frail older adults are more likely to have complications postoperatively
• Likelihood of increased hospital stays, and discharged to a skilled or assisted living facility increases
• Results from decreased resistance to stressors as a result of deterioration in multiple physiologic systems
• Classified as primary or secondary
• ACS NSQIP/AGS guidelines recommends that elderly surgical patients be assessed for frailty via a validated screening tool: Fried et al. created an operational frailty score

Nutritional Status

• A nutritional assessment is imperative in the older adult surgical patient
• No uniform definition for malnutrition, but most definitions include specific laboratory indices, and body mass index (BMI)
• Results in postoperative complications, increased hospital cost, and death
• Nutritional status assessment is crucial for assessing the patient's condition and potential interventions

Functional Status

• Identifies the ability to perform self-care tasks, or activities of daily living (i.e., bathing, dressing, toileting), and instrumental activities of daily living (i.e., preparing meals, handling finances, driving or using public transportation)
• Inquiring about falls and visualizing gait and mobility helps determines risk of complications
• Proxies are suitable for assessing functional decline

Review of Medications and Polypharmacy

• A review of all medications is critical to identify what should be continued after consult
• Adverse drug reactions common in older patients
• Caused by prescribing error or not taking into account CNS sensitivity
• ACS NSQIP/AGS guidelines medication review should aim for
• Discontinuation/Substituting dangerous drugs
• Identify medication based on Beer's criteria

Age-Related Pharmacologic Implications in the Older Adult

• Result of both pharmacokinetic and pharmacodynamic changes are associated with aging
• Decreased blood volume results in a decrease in initial volume of distribution, which produces a higher-than-expected initial concentration of drug with an intravenous bolus injection
• Plasma protein binding decrease in the elderly can increase the effect of serum contractions

Comorbidity in the Older Adult

• Defined as two or more chronic medical conditions, multimorbidity has increased with age, even though mortality rates have declined
• Multimorbidity increases steeply with older adults