Perioperative Considerations in Care of the Elderly

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Perioperative Considerations in Care of the
Elderly

• Fred Weitz MD
• Emory University
• Dept. of Anesthesiology

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Realities for the Practicing Anesthesiologist

• More than 35 million people in U.S. are gt 65
• They account for almost half of hospital care
  days
• 25-35 surgical cases
• Most anesthesiologists are geriatric
  anesthesiologists!

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All Geriatric Patients are not Created Equal!
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People age at different ratesOrgan Function
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Organ Functional ReserveSafety Margin of Organ
Capacity
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Considerations

• Cardiovascular function
• Respiratory function
• Airway Management
• Pharmacokinetics
• Body temperature regulation
• Postoperative Mental function

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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

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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

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Arterial Stiffening

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

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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

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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

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Ventricular Contraction

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

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Dependence on High Filling Pressure
Frank-Starling Curve
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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 gt 75 y/o

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Can the Elderly Heart Increase Output?
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Aging and ContractilityResponse to Exercise
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0
Young
6
5
Ejection Fraction ()
Elderly
6
0
5
5
At Rest
Maximal Exercise
Stratton et al., Circ 1994891648
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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

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Response to Anesthesia

• Anesthetics can
• Remove sympathetic tone
• Dramatic when baseline tone is very high
• Directly depress heart, vascular smooth muscle
• Diminish baroreceptor reflexes

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Add to That

• Changes in sympathetic tone from
• waxing and waning surgical stimulus
• variable depth of anesthesia
• Changes in patients volume status
• Results in LABILE BLOOD PRESSURE !

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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

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Summary Decreased Response to Beta-Receptor
Stimulation

• Lessened ability to increase in heart rate
• Lessened ability to increase ejection fraction

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Aging and Respiratory Function
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Lung VolumesDecreased VC and Increased RV
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Pulmonary Changes

• Decreased thoracic elasticity
• Decreased strength and endurance of respiratory
  muscles

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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

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Increased Shunt
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Explains Effect of Age on paO2
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Pre-oxygenation

• Takes longer in elderly than in healthy young
  patients!

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Airway ManagementDiminished Afferentation

• Stimulus threshold for vocal cord closure is
  increased
• Increased risk of aspiration!

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Airway ManagementChanges with Aging

• Arthritic Changes
• Decreased cervical spine and neck mobility
• Smaller mouth opening
• Smaller glottic opening
• Smaller endotracheal tube
• Fragile teeth

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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

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

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Increased Brain Sensitivity

• Elderly brain is more sensitive to a given CNS
  level of a drug
• Mechanism ??

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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

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Bolus Drug Strategy for the Elderly

• GO LOW !
• GO SLOW !
• You can always give more!

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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

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The Elderly Brain
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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

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Postoperative Cognitive Disorders

• Delirium
• Mild neurocognitive disorder - POCD
• Dementia (rare)
• Multiple cognitive deficits
• Impairment in activities of daily living

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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

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Postoperative DeliriumPredisposing Factors

• Drug withdrawal
• Use of benzodiazepines, tricyclic antidepressants
• Alcohol abuse
• Drug interactions
• Anticholinergics, etc.
• Pre-existing depression or dementia
• Metabolic disturbances

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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 gt 90
• Maintained Hct gt 30
• Mobilized patients ASAP
• Provided appropriate environmental stimulation

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Minimizing Postoperative DeliriumTry to Avoid

• Anticholinergics - atropine and scopolamine (NOT
  glycopyrrolate)
• Ketamine
• Benzodiazepines
• Large doses of barbiturates and Propofol
• Meperidine

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Common Treatable Causes of Postoperative
Delirium

• Hypoxemia
• Hypercarbia
• Hypotension
• Pain
• Sepsis
• Metabolic

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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.
  Parkinsons Disease)
• Restraints - to prevent injury

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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

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

• Collaborative research effort
• 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
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Incidence of POCD in Patients and
ControlsPatients gt 60 y.o.
Lancet 1998 351857
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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
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The Relationship Between Age and
POCDInclusion/Exclusion Criteria

• Inclusion criteria
• Aged 18 years or older
• General anesthesia gt 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
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Incidence of POCD in Adult Patients
of Patients
13
p lt 0.05
Monk et al. Anesthesiology 2001 95 A-50
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Predictors of POCD3 Months After Surgery
Monk et al. Anesthesiology 2001 95 A-50
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One Year Mortality Rate and POCD in Elderly
Patients
Monk et al. Anesthesiology 2001 95 A-50
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Independent Multivariate Predictors of One-Year
Mortality
Multivariate c-statistic 0.806 (p lt 0.001)
Monk et al. Anesthesiology 2001 95 A-50
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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
  Monks POCD/Mortality Study

Lennmarken et al, Anesthesiology 2003 99A-303
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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

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POCD Multifactorial?

• Pre-existing cognitive dysfunction
• Complexity and duration of surgery
• Micro emboli
• Inflammation
• Stress, social isolation, immobility

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