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

En

d-D

iast

olic

Pre

ssu

re

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

55

60

65

70

Young

Eje

ctio

n F

ract

ion

(%)

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 AgingBerlin Aging Study

Threshold Theory for Cognitive Decline

LesionLesion

LesionLesionProtectiveFactor

Case ACase A Case BCase B

Bra

in R

eser

ve C

apac

ity

Bra

in R

eser

ve C

apac

ity

A: Protective factor (greater brain reserve capacity), no impairmentA: Protective factor (greater brain reserve capacity), no impairment

B: Vulnerability factor (less brain reserve capacity), impairmentB: Vulnerability factor (less brain reserve capacity), impairment

Satz Neuropsychology 1993:(7);273.

International Study of POCD

Long-term postoperative cognitive dysfunctionLong-term postoperative cognitive dysfunctionin the elderly: ISPOCD1 studyin the elderly: ISPOCD1 study

JT Moller P Cluitmans LS Rasmussen P Houx H Rasmussen J CanetJT Moller P Cluitmans LS Rasmussen P Houx H Rasmussen J CanetP Rabbitt J Jolles K Larsen CD Hanning O Langeron T Johnson PM LauvenP Rabbitt J Jolles K Larsen CD Hanning O Langeron T Johnson PM Lauven

PA Kristensen A Biedler H van Beem O Fraidakis, JH SilversteinPA Kristensen A Biedler H van Beem O Fraidakis, JH SilversteinJEW Beneken JS Gravenstein for the ISPOCD investigatorsJEW Beneken JS Gravenstein for the ISPOCD investigators

THE LANCET Saturday 21 March 1998Vol. 351 No. 9106 Pages 857-861

Collaborative research effort:– Members from 8 European countries and USA– 13 hospitals– Research conducted from 1994 - 1996

Incidence of POCD in Patients and Controls:Patients > 60 y.o.

Lancet 1998; 351:857Lancet 1998; 351:857

0

5

10

15

20

25

30

Pe

rce

nta

ge

(%

)

Early Late

Controls

Patients

*

10 %

* p < 0.004* p < 0.004

26 %

A Prospective Study EvaluatingThe Relationship Between Age and POCD

Single site - University of Florida: 1999 - 2002 1200 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*p < 0.05

Monk et al. Anesthesiology 2001; 95: A-50

% o

f P

atie

nts

13 %

Predictors of POCD:3 Months After Surgery

NS0.046 History of MI

NS0.021 Baseline ComorbidityNS0.009 ASA Physical StatusNS0.003 History of Stroke

2.51 (p=0.057)0.001 Age0.86 (p=0.028) < 0.001 Years of Education

NS0.028 NYHA Status

NSNS Anesthesia TimeNSNS Baseline MMSENSNS GenderNSNS Surgery Type

Multivariate Odds Ratio Univariate P value Risk Factors for POCD

Multivariate c-statistic = 0.671 (p = 0.003)

Monk et al. Anesthesiology 2001; 95: A-50

One Year Mortality Rate and POCD in Elderly Patients

3.4%2.4%

6.5%

8.1%

0%

2%

4%

6%

8%

10%

Hospital Discharge Three Months

No Decline Cognitive Decline

* **

* P = 0.027 vs. No Decline; ** P = 0.014 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 Comorbidity 16.86 < 0.001

Volatile vs. TIVA 2.97 0.022

Intraoperative Beta Blocker 1.67 0.004

Chronic Beta Blocker 1.53 0.019

Cumulative Deep Anesthesia Time (BIS < 45, per hour) 1.34 0.007

Systolic Blood Pressure < 80 mmHg (per minute) 1.04 0.008

Multivariate c-statistic = 0.806 (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