Transcript Document

Perioperative Considerations in
Care of the Elderly
Fred Weitz MD
Emory University
Dept. of Anesthesiology
Realities for the Practicing
Anesthesiologist
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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:
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Cardiovascular function
Respiratory function
Airway Management
Pharmacokinetics
Body temperature regulation
Postoperative Mental function
CV Changes with Aging
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Connective tissue changes
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Loss of elasticity
Loss of SA node cells, slowed conduction
Myocyte death without replacement
Decreased response to beta-receptor
stimulation
Aging Does Not Diminish:
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Intrinsic quality of muscle
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Heart does not weaken with age alone
Peripheral vasoconstriction
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Enhanced sympathetic nervous system activity at
rest
More prone to hypotension with loss of sympathetic
tone
Arterial Stiffening
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Reflected pressure from “stiffened arteries”
increases pressure in aortic root during
late systole
Leads to ventricular hypertrophy, impaired
diastolic filling
Decreased Venous Compliance
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Veins, like arteries, stiffen with age
Stiff veins are less able to “buffer” changes in
blood volume
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Volume shifts cause exaggerated changes in
cardiac filling pressure
Myocyte Death
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Cardiac muscle cells die over time
Remaining cells do not divide in adequate
numbers in adulthood
Remaining cells hypertrophy to compensate
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Another cause of ventricular hypertrophy
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Ventricular Contraction
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Slows with Aging
Ventricle may not be fully relaxed during
beginning of diastolic filling phase
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Result: Early diastolic filling is impaired
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End-Diastolic Pressure
Dependence on High Filling Pressure
Elderly
Young
End-Diastolic Volume
Frank-Starling Curve
Consequences of Delayed
Relaxation
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Late diastolic filling depends on high left atrial
pressure and atrial kick
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Tachycardia and atrial fibrillation not well tolerated
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Narrow range between inadequate filling
pressure and fluid overload
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Diastolic dysfunction may be the most common
cause of heart failure in > 75 y/o
Can the Elderly Heart Increase
Output?
Ejection Fraction
(%)
Aging and Contractility:
Response to Exercise
70
Young
65
Elderly
60
55
At Rest
Maximal
Exercise
Stratton et al., Circ
1994;89:1648
Decreased Beta-Receptor
Responsiveness
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Diminished increase in heart rate with stress
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Reduced maximum heart rate
Increase their stroke volume
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From increase in end diastolic volume
Response to Anesthesia
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Anesthetics can:
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Remove sympathetic tone
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Dramatic when baseline tone is very high
Directly depress heart, vascular smooth muscle
Diminish baroreceptor reflexes
Add to That …
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Changes in sympathetic tone from
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waxing and waning surgical stimulus
variable depth of anesthesia
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Changes in patient’s volume status
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Results in LABILE BLOOD PRESSURE !
Summary: Volume Dependence of
the Elderly Heart
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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
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Lessened ability to increase in heart rate
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Lessened ability to increase ejection fraction
Aging and Respiratory Function
Lung Volumes:
Decreased VC and Increased RV
Pulmonary Changes
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Decreased thoracic elasticity
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Decreased strength and endurance of
respiratory muscles
Decreased Efficiency of Gas
Exchange
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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:
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Shunting
Dead space
Increased Shunt
Explains Effect of Age on paO2
Pre-oxygenation
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Takes longer in elderly than in healthy young
patients!
Airway Management:
Diminished Afferentation
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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
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Smaller endotracheal tube
Fragile teeth
Remember…
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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
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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
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Decreased protein binding
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Higher free, unbound plasma drug levels
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Decreased volume of distribution
Slower redistribution of drug
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ALL of these INCREASE target organ levels!
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Examples: Thiopental, Propofol
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Increased Brain Sensitivity
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Elderly brain is more sensitive to a given CNS
level of a drug
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Mechanism ??
Slowed Drug Metabolism:
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Clearance decreases as
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Liver blood flow decreases
Liver mass decreases
Kidney function decreases
Volume of distribution increases with
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Increased body fat
Decreased albumin levels
Bolus Drug Strategy for the Elderly:
GO LOW !
 GO SLOW !
 You can always give more!
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Temperature Regulation
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Elderly prone to both hypo-, hyperthermia
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Lower body metabolism
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Decreased ability to change skin blood
flow (less able to hold or get rid of heat)
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Hypothermia
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Shivering increases metabolic demand
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Increased risk of myocardial ischemia
The Elderly Brain
CNS Structural Changes
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Brain mass decreases with corresponding
decreased cerebral blood flow
Decreased receptors
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Acetylcholine
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Cholinergic neurons in the basal forebrain regulate normal
memory
Dopamine
Norepinephrine
Postoperative Cognitive Disorders
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Delirium
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Mild neurocognitive disorder - POCD
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Dementia (rare)
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Multiple cognitive deficits
Impairment in activities of daily living
Postoperative Delirium
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Most common form of perioperative CNS dysfunction
Acute confusion, decreased alertness,
misperception
Patient may show agitation or withdrawal
Twice as common in the elderly
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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
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Drug withdrawal
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Drug interactions
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Use of benzodiazepines, tricyclic antidepressants
Alcohol abuse
Anticholinergics, etc.
Pre-existing depression or dementia
Metabolic disturbances
Can Postoperative Delirium be
Prevented?
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Marcantonio (2001) - Reduced postoperative
delirium by 1/3 in hip fracture patients
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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:
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Anticholinergics - atropine and scopolamine
(NOT glycopyrrolate)
Ketamine
Benzodiazepines
Large doses of barbiturates and Propofol
Meperidine
Common & Treatable Causes of
Postoperative Delirium
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Hypoxemia
Hypercarbia
Hypotension
Pain
Sepsis
Metabolic
Management of Postoperative
Delirium
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Identify cause if possible
Maintain or restore:
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Drugs
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Adequate oxygenation and ventilation
Normal hemodynamics
Normal metabolic state
Benzodiazepines - if alcohol or sedative withdrawal
Haloperidol (if not contraindicated - i.e. Parkinson’s Disease)
Restraints - to prevent injury
Postoperative Cognitive Dysfunction
(POCD)
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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:
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corroborated with neuropsychological testing and
evidence of greater memory loss than one would
expect due to normal aging
Implications of POCD:
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Can lead to an abrupt decline in cognitive
function
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Ultimately
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Loss of independence
Withdrawal from society
Death
Seattle Longitudinal Study of Aging
Berlin Aging Study
Brain Reserve Capacity
Threshold Theory for Cognitive
Decline
Lesion
Protective
Factor
Case A
Lesion
Case B
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
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Collaborative research effort:
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Members from 8 European countries and USA
13 hospitals
Research conducted from 1994 - 1996
THE LANCET Saturday 21 March 1998
Vol. 351 No. 9106 Pages 857-861
Incidence of POCD in Patients and
Controls:
Patients > 60 y.o.
*
26 %
10 %
* p < 0.004
Lancet 1998; 351:857
A Prospective Study Evaluating
The Relationship Between Age and POCD
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Single site - University of Florida: 1999 - 2002
1200 patients undergoing elective surgery
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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
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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
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Inclusion criteria
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Aged 18 years or older
General anesthesia > 2 hrs
Major abdominal/thoracic or orthopedic surgery
Mini-Mental Status Exam (MMSE) ≥ 24
Exclusion criteria
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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
% of Patients
Incidence of POCD in Adult Patients:
13 %
*p < 0.05
Monk et al. Anesthesiology 2001; 95: A-50
Predictors of POCD:
3 Months After Surgery
Risk Factors for POCD
Years of Education
Age
History of Stroke
ASA Physical Status
Baseline Comorbidity
NYHA Status
History of MI
Surgery Type
Gender
Baseline MMSE
Anesthesia Time
Univariate P value
< 0.001
0.001
0.003
0.009
0.021
0.028
0.046
Multivariate Odds Ratio
0.86 (p=0.028)
2.51 (p=0.057)
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
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
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* 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
Baseline Comorbidity
Volatile vs. TIVA
Intraoperative Beta Blocker
Chronic Beta Blocker
Cumulative Deep Anesthesia Time (BIS < 45, per hour)
Systolic Blood Pressure < 80 mmHg (per minute)
Relative Risk
16.86
2.97
1.67
1.53
1.34
1.04
P Value
< 0.001
0.022
0.004
0.019
0.007
0.008
Multivariate c-statistic = 0.806 (p < 0.001)
Monk et al. Anesthesiology 2001; 95: A-50
Is Mortality Data Reproducible?
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Multi-center Prospective Trial (Sweden)
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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
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Culley (2003) - Found that isoflurane-nitrous
anesthesia without surgery in rats impairs
spatial learning for weeks in elderly rats
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Eckenhoff (2004) - Found increased toxicity of
beta-amyloid in cell cultures induced by
common general anesthetics
POCD: Multifactorial?
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Pre-existing cognitive dysfunction
Complexity and duration of surgery
Micro emboli
Inflammation
Stress, social isolation, immobility