GERIATRIC ANESTHESIA: AN INTRODUCTION Jeannette Lee, MD Anesthesiology Resident Ruben J. Azocar, MD Associate Professor of Anesthesiology THE AMERICAN GERIATRICS SOCIETY Geriatrics Health Professionals. Leading change. Improving care for older adults. AGS

OBJECTIVES Review the ongoing demographic changes in the elderly segment of the population Analyze the impact of the growing geriatric populations in health care Summarize the most important physiologic changes that occur with aging Slide 2

ELDERLY POPULATION “Elderly” is defined as >65 years old “Very old” is defined as >85 years old The elderly population currently comprises 12% of the US population  Projected to increase to 20% by 2040 Slide 3

ELDERLY POPULATION IN THE US Slide 4

ELDERLY POPULATION IN THE US Slide 5

THE ELDERLY AS A PROPORTION OF THE US POPULATION Slide 6

GLOBAL ELDERLY POPULATION In 2000 the global population >65 years old was estimated to be 420 million It is projected that by 2010, the elderly population will increase 847,000 per month Slide 7

GLOBAL ELDERLY POPULATION Slide 8

PROCEDURES FOR THE ELDERLY From 1994  2005 the average number of inpatient procedures per year in patients >65 years old increased from 6,500,000 to 7,353,000 Currently 35% of all surgical procedures are performed in elderly patients More than half of the elderly population will have at least one procedure done before they die Slide 9

POSTOPERATIVE MORTALITY IN THE ELDERLY Slide 10 Monk et al reported a prospective observational study of 1064 patients undergoing noncardiac surgery > 65 yo had a 1-year mortality rate of 10.3% vs. 5.5% in all patients >65 yo had a relative risk of 1-year postoperative mortality of 4.459, which was the third highest risk factor, after having 3 or more comorbidities or an ASA of 3 or 4. Monk TG et al. Anesth Analg. 2005;100:4-10.

PHYSIOLOGIC CHANGES WITH AGING Functional and structural changes occur in most organ systems Although the basal function may remain stable in various organs systems, the functional reserve and the ability to compensate under physiologic stress are greatly reduced Slide 11

PHYSIOLOGIC CHANGES WITH AGING: BODY COMPOSITION Skeletal muscle mass decreased Percentage of body fat increased Total body water decreased  Water-soluble drugs: reduced volume of distribution  Lipid-soluble drugs: increased volume of distribution DO 2 and heat production decreased Slide 12

PHYSIOLOGIC CHANGES WITH AGING: CENTRAL NERVOUS SYSTEM Brain mass decreases, mainly from loss of neural tissue 10%  20% reduction in cerebral blood flow Decreased number of serotonin, acetylcholine, and dopamine receptors Decline in memory, reasoning, perception Disturbed sleep/wake cycle Slide 13

PHYSIOLOGIC CHANGES WITH AGING: CARDIOVASCULAR SYSTEM LV hypertrophy and decreased compliance Increase in vascular rigidity  Decreased compliance of venous vessels Desensitization of β-adrenergic receptors  Decreased PNS tone and increased SNS tone SVR and SBP increased SV and CO decreased Diastolic LV dysfunction Decreased maximally attainable HR Slide 14

PHYSIOLOGIC CHANGES WITH AGING: PULMONARY SYSTEM ↑ Central airway size and ↓ small airway diameter  no change in airway resistance ↓ Functional alveolar surface area ↓ Gas exchange  ↓ PaO 2 and ↑ A  a gradient ↑ Lung compliance and RV leads to ↑ FRC No changes in TLC  Result is ↑ RV/TLC and FRC/TLC ratios ↓ Elastic tissue ↑ Amount of collagen Reorientation of elastic fibers Slide 15

PHYSIOLOGIC CHANGES WITH AGING: PULMONARY SYSTEM DecreaseIncrease Respiratory muscle strength Chest wall height Respiratory center sensitivity Chest wall compliance Effective cough and swallow  ↑ aspiration risk D LCO2 P IMAX and P EMAX ERV and VC FVC, FEV1, FEV1/VC, and FEF at low lung volumes Chest wall stiffness AP diameter Closing volume and closing capacity Slide 16

PHYSIOLOGIC CHANGES WITH AGING: RENAL SYSTEM Tissue mass decreased Perfusion decreased GFR decreased Reduced ability to dilute and concentrate urine and conserve sodium Drug clearance decreased Slide 17

PHYSIOLOGIC CHANGES WITH AGING: HEPATIC SYSTEM Tissue mass decreased Blood flow decreased Possible decrease in affinity for substrate Possible decrease in intrinsic activity Decreased first-pass metabolism of some drugs Slide 18

PHYSIOLOGIC CHANGES WITH AGING: ENDOCRINE CHANGES ↓ ADH response to hypovolemia and hypotension ↓ Renin and aldosterone leads to ↓ response to sodium restriction and postural changes are blunted No changes in adrenocorticotropic hormone, cortisol, catecholamine production in adrenal medulla, or TSH Insulin release is impaired  Impaired peripheral tissue resistance and decreased clearance leads to ↑ plasma insulin levels and ↑ fat deposits Slide 19

PHYSIOLOGIC CHANGES WITH AGING: PK AND PD ISSUES Protein binding  ↓ Level of proteins  Multiple medications interfere with drug binding sites  ↑ Level of free unbound drug in plasma  prolonged effect ↓ Lean and ↑ fat body mass  ↑ Storage of lipid-soluble drugs  prolonged effect and longer time for elimination ↓ Circulating blood volume  ↑ Initial plasma drug concentration Slide 20

CONCLUSIONS The proportion of older individuals in the US population continues to rise Many of them will require surgery and anesthesia Physiologic changes of age have a great impact in the perioperative period Slide 21

ACKNOWLEDGMENTS Supported by a grant from the Geriatric Education for Specialty Residents Program (GS), which is administered by the American Geriatrics Society and funded by the John A. Hartford Foundation of New York City Our gratitude to Dr. Alec Rooke for his assistance with many of these slides Slide 22

Visit us at: Facebook.com/AmericanGeriatricsSociety Twitter.com/AmerGeriatrics THANK YOU FOR YOUR TIME! linkedin.com/company/american-geriatrics- society Slide 23