Perioperative Considerations in Care of the Elderly Fred Weitz MD Emory University Dept. of Anesthesiology

Realities for the Practicing Anesthesiologist More than 35 million people in U.S. are > 65 They account for almost half of hospital care days 25-35% surgical cases Most anesthesiologists are geriatric anesthesiologists!

All Geriatric Patients are not Created Equal!

People age at different rates: Organ Function

Organ Functional Reserve: Safety Margin of Organ Capacity

Considerations: Cardiovascular function Respiratory function Airway Management Pharmacokinetics Body temperature regulation Postoperative Mental function

CV Changes with Aging Connective tissue changes – Loss of elasticity Loss of SA node cells, slowed conduction Myocyte death without replacement Decreased response to beta-receptor stimulation

Aging Does Not Diminish: Intrinsic quality of muscle – Heart does not weaken with age alone Peripheral vasoconstriction – Enhanced sympathetic nervous system activity at rest – More prone to hypotension with loss of sympathetic tone

Arterial Stiffening Reflected pressure from “stiffened arteries” increases pressure in aortic root during late systole Leads to ventricular hypertrophy, impaired diastolic filling

Decreased Venous Compliance Veins, like arteries, stiffen with age Stiff veins are less able to “buffer” changes in blood volume – Volume shifts cause exaggerated changes in cardiac filling pressure

Myocyte Death Cardiac muscle cells die over time Remaining cells do not divide in adequate numbers in adulthood Remaining cells hypertrophy to compensate Another cause of ventricular hypertrophy

Ventricular Contraction Slows with Aging Ventricle may not be fully relaxed during beginning of diastolic filling phase Result: Early diastolic filling is impaired

Dependence on High Filling Pressure Young End-Diastolic Volume End-Diastolic Pressure Elderly Frank-Starling Curve

Consequences of Delayed Relaxation Late diastolic filling depends on high left atrial pressure and atrial kick – Tachycardia and atrial fibrillation not well tolerated Narrow range between inadequate filling pressure and fluid overload Diastolic dysfunction may be the most common cause of heart failure in > 75 y/o

Can the Elderly Heart Increase Output?

Aging and Contractility: Response to Exercise Young Ejection Fraction (%) At Rest Maximal Exercise Elderly Stratton et al., Circ 1994;89:1648

Decreased Beta-Receptor Responsiveness Diminished increase in heart rate with stress – Reduced maximum heart rate Increase their stroke volume – From increase in end diastolic volume

Response to Anesthesia Anesthetics can: – Remove sympathetic tone – Dramatic when baseline tone is very high – Directly depress heart, vascular smooth muscle – Diminish baroreceptor reflexes

Add to That … Changes in sympathetic tone from waxing and waning surgical stimulus variable depth of anesthesia Changes in patient’s volume status Results in LABILE BLOOD PRESSURE !

Summary: Volume Dependence of the Elderly Heart Elderly heart depends on late filling that in turn depends on left atrial pressure Elderly heart is also stiff, so the left atrial pressure must be high in order to fill the LV prone to diastolic dysfunction poor venous buffering of blood volume makes maintenance of left atrial pressure difficult

Summary: Decreased Response to Beta-Receptor Stimulation Lessened ability to increase in heart rate Lessened ability to increase ejection fraction

Aging and Respiratory Function

Lung Volumes: Decreased VC and Increased RV

Pulmonary Changes Decreased thoracic elasticity Decreased strength and endurance of respiratory muscles

Decreased Efficiency of Gas Exchange Breakdown of elastin connections between connective tissue and alveolar tissue Results in poor tethering of lung tissue to airways and other lung tissue Airways are NOT held open Increases: – Shunting – Dead space

Increased Shunt

Explains Effect of Age on paO2

Pre-oxygenation Takes longer in elderly than in healthy young patients!

Airway Management: Diminished Afferentation Stimulus threshold for vocal cord closure is increased Increased risk of aspiration!

Airway Management: Changes with Aging Arthritic Changes: Decreased cervical spine and neck mobility Smaller mouth opening Smaller glottic opening – Smaller endotracheal tube Fragile teeth

Remember… Airway management may be more difficult Prone to airway collapse (risk of pneumonia) Higher work of breathing (risk of hypercarbia) Lower blood oxygen levels (greater need for supplemental oxygen) After leaving PACU, hypoxia more likely – from residual drug/CNS effects

Geriatric population is at significantly increased risk of respiratory failure in the postoperative setting!

Pharmacology in the Elderly Patient

Increased Bolus Drug Effect Decreased protein binding – Higher free, unbound plasma drug levels Decreased volume of distribution Slower redistribution of drug ALL of these INCREASE target organ levels! Examples: Thiopental, Propofol

Increased Brain Sensitivity Elderly brain is more sensitive to a given CNS level of a drug Mechanism ??

Slowed Drug Metabolism: Clearance decreases as – Liver blood flow decreases – Liver mass decreases – Kidney function decreases Volume of distribution increases with – Increased body fat – Decreased albumin levels

Bolus Drug Strategy for the Elderly: GO LOW ! GO SLOW ! You can always give more!

Temperature Regulation Elderly prone to both hypo-, hyperthermia Lower body metabolism Decreased ability to change skin blood flow (less able to hold or get rid of heat) Hypothermia – Shivering increases metabolic demand Increased risk of myocardial ischemia

The Elderly Brain

CNS Structural Changes Brain mass decreases with corresponding decreased cerebral blood flow Decreased receptors – Acetylcholine Cholinergic neurons in the basal forebrain regulate normal memory – Dopamine – Norepinephrine

Postoperative Cognitive Disorders Delirium Mild neurocognitive disorder - POCD Dementia (rare) – Multiple cognitive deficits – Impairment in activities of daily living

Postoperative Delirium Most common form of perioperative CNS dysfunction Acute confusion, decreased alertness, misperception Patient may show agitation or withdrawal Twice as common in the elderly – 10-15% of elderly surgical patients – 30-50% if undergoing cardiac or orthopedic surgery Seen after general, regional and MAC anesthetics Results in prolonged hospital stay and protracted postoperative care

Postoperative Delirium: Predisposing Factors Drug withdrawal – Use of benzodiazepines, tricyclic antidepressants – Alcohol abuse Drug interactions – Anticholinergics, etc. Pre-existing depression or dementia Metabolic disturbances

Can Postoperative Delirium be Prevented? Marcantonio (2001) - Reduced postoperative delirium by 1/3 in hip fracture patients – Minimized benzodiazepines, anticholinergics, antihistamines, meperidine – Maintained BP greater than 2/3 of baseline – Maintained O2 saturation > 90% – Maintained Hct > 30% – Mobilized patients ASAP – Provided appropriate environmental stimulation

Minimizing Postoperative Delirium: Try to Avoid: Anticholinergics - atropine and scopolamine (NOT glycopyrrolate) Ketamine Benzodiazepines Large doses of barbiturates and Propofol Meperidine

Common & Treatable Causes of Postoperative Delirium Hypoxemia Hypercarbia Hypotension Pain Sepsis Metabolic

Management of Postoperative Delirium Identify cause if possible Maintain or restore: – Adequate oxygenation and ventilation – Normal hemodynamics – Normal metabolic state Drugs – Benzodiazepines - if alcohol or sedative withdrawal – Haloperidol (if not contraindicated - i.e. Parkinson’s Disease) Restraints - to prevent injury

Postoperative Cognitive Dysfunction (POCD) Deterioration of intellectual function presenting as impaired memory or concentration. Not detected until days or weeks after surgery Duration of several weeks to permanent Diagnosis is only warranted if: – corroborated with neuropsychological testing and evidence of greater memory loss than one would expect due to normal aging

Implications of POCD: Can lead to an abrupt decline in cognitive function Ultimately – Loss of independence – Withdrawal from society – Death Seattle Longitudinal Study of Aging Berlin Aging Study

Threshold Theory for Cognitive Decline Lesion Lesion Protective Factor Case A Case B Brain Reserve Capacity A: Protective factor (greater brain reserve capacity), no impairment B: Vulnerability factor (less brain reserve capacity), impairment Satz Neuropsychology 1993:(7);273.

International Study of POCD Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study JT Moller P Cluitmans LS Rasmussen P Houx H Rasmussen J Canet P Rabbitt J Jolles K Larsen CD Hanning O Langeron T Johnson PM Lauven PA Kristensen A Biedler H van Beem O Fraidakis, JH Silverstein JEW Beneken JS Gravenstein for the ISPOCD investigators THE LANCET Saturday 21 March 1998 Vol. 351 No Pages Collaborative research effort: – Members from 8 European countries and USA – 13 hospitals – Research conducted from

Incidence of POCD in Patients and Controls: Patients > 60 y.o. Lancet 1998; 351:857 * 10 % * p < %

A Prospective Study Evaluating The Relationship Between Age and POCD Single site - University of Florida: patients undergoing elective surgery – Young - 18 to 39 years of age – Middle-aged - 40 to 59 years of age – Elderly - 60 years and older Controls - primary family members Study design identical to ISPOCD study – Same psychometric test battery – Outcome Endpoints: POCD (primary) and mortality (secondary) Monk et al. Anesthesiology 2001; 95: A-50

The Relationship Between Age and POCD: Inclusion/Exclusion Criteria Inclusion criteria – Aged 18 years or older – General anesthesia > 2 hrs – Major abdominal/thoracic or orthopedic surgery – Mini-Mental Status Exam (MMSE) ≥ 24 Exclusion criteria – Cardiac or neurosurgical procedures – CNS disease – Alcoholism or drug dependence – Major depression – Patients not expected to live 3 months or longer Monk et al. Anesthesiology 2001; 95: A-50

Incidence of POCD in Adult Patients: *p < 0.05 Monk et al. Anesthesiology 2001; 95: A-50 % of Patients 13 %

Predictors of POCD: 3 Months After Surgery NS0.046 History of MI NS0.021 Baseline Comorbidity NS0.009 ASA Physical Status NS0.003 History of Stroke 2.51 (p=0.057)0.001 Age 0.86 (p=0.028) < Years of Education NS0.028 NYHA Status NS Anesthesia Time NS Baseline MMSE NS Gender NS Surgery Type Multivariate Odds Ratio Univariate P value Risk Factors for POCD Multivariate c-statistic = (p = 0.003) Monk et al. Anesthesiology 2001; 95: A-50

One Year Mortality Rate and POCD in Elderly Patients * ** * P = vs. No Decline; ** P = vs. No Decline Monk et al. Anesthesiology 2001; 95: A-50

Independent Multivariate Predictors of One-Year Mortality Risk Factors Relative Risk P Value Baseline Comorbidity16.86< Volatile vs. TIVA Intraoperative Beta Blocker Chronic Beta Blocker Cumulative Deep Anesthesia Time (BIS < 45, per hour) Systolic Blood Pressure < 80 mmHg (per minute) Multivariate c-statistic = (p < 0.001) Monk et al. Anesthesiology 2001; 95: A-50

Is Mortality Data Reproducible? Multi-center Prospective Trial (Sweden) – 5,057 General Anesthetics, Non-cardiac Surgery Similar 1 Year Mortality Rate Deep anesthesia time is a significant independent predictor of mortality – Increased Relative Risk: 19.7% / hr. vs. 34.1% in Monk’s POCD/Mortality Study Lennmarken et al, Anesthesiology 2003; 99:A-303

Laboratory Findings Culley (2003) - Found that isoflurane-nitrous anesthesia without surgery in rats impairs spatial learning for weeks in elderly rats Eckenhoff (2004) - Found increased toxicity of beta-amyloid in cell cultures induced by common general anesthetics

POCD: Multifactorial? Pre-existing cognitive dysfunction Complexity and duration of surgery Micro emboli Inflammation Stress, social isolation, immobility