geriatric anesthesia: an introduction jeannette lee, md anesthesiology resident ruben j. azocar, md...
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GERIATRIC ANESTHESIA:AN INTRODUCTION
Jeannette Lee, MDAnesthesiology 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 PROPORTIONOF 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 7http://www.census.gov/prod/2001pubs/p95-01-1.pdf
GLOBAL ELDERLY POPULATION
Slide 8
PROCEDURES FOR THE ELDERLY
• From 19942005 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 9www.cdc.gov/nchs/data/hus/hus07.pdf#102
POSTOPERATIVE MORTALITYIN 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 decreasedWater-soluble drugs: reduced volume of distributionLipid-soluble drugs: increased volume of distribution
• DO2 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 ↓ PaO2 and ↑ Aa gradient
• ↑ Lung compliance and RV leads to ↑ FRC• No changes in TLC
Result is ↑ RV/TLC and FRC/TLC ratios
Slide 15
PHYSIOLOGIC CHANGES WITH AGING:PULMONARY SYSTEM
Decrease Increase• Respiratory muscle strength • Chest wall height• Respiratory center sensitivity• Chest wall compliance• Effective cough and swallow ↑
aspiration risk
• DLCO2
• PIMAX and PEMAX
• 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
www.americangeriatrics.org
THANK YOU FOR YOUR TIME!
linkedin.com/company/american-geriatrics-society
Slide 23
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