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Critical Care for Older Adults

Dorothy W. Bird, MD*

Lisa B. Caruso, MD, MPH†

Suresh Agarwal, MD, FACS*

Boston University Medical Center

Department of Surgery*, Department of Medicine- Geriatric Services†

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Introduction

• Older adults (age >65yo) are the fastest growing segment of the US population (ref: 1,2)

• Almost HALF of all ICU admissions are older adults (ref: 1,2)

– Exacerbation of chronic illness

– New onset of illness or trauma

• By 2030 20% of Americans will be >65yo (ref: 1)

• By 2050 5% of Americans will be >85yo (ref: 1)

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Introduction

• Older adults differ from their younger ICU counterparts in several ways:

– Physiology (cardiopulmonary, renal)

– Drug metabolism

– Nutritional needs

– Susceptibility to delirium

– ICU outcomes

– Closer to end of life

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Cardiovascular Changes

• Age-related changes in collagen, elastin→loss of recoil (ref: 3)

– Increased systolic blood pressure

– Widened pulse pressure (ref: 1)

– Progressive left ventricular stiffness, thickness →Diastolic Dysfunction (ref: 1,2,3)

• Less able to tolerate atrial fibrillation

• Increased sensitivity to volume overload

• Increased susceptibility to heart failure

• Increased preload dependency

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Cardiovascular Changes

• Fewer cardiac myocytes (ref: 2,4)

• Fibrosis/loss of autonomic tissue (ref: 2)

– Conduction abnormalities (sick sinus, a-fib, BBB)

• Diminished sensitivity to β-adrenergic stimulation (ref: 1,2,3,4)

– Stroke volume, preload more important for increasing cardiac output

– Even minor hypovolemia can cause cardiac impairment (Increased preload dependency)

– Diminished response to norepinephrine, isoproterinol, dobutamine

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Cardiovascular Risk Factors

• Increased prevalence of coronary artery disease in older adults (ref: 1,2,3)

– May present as heart failure, pulmonary edema, arrhythmias

– Myocardial ischemia more likely to go unrecongnized

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Pulmonary Changes

• Increased chest rigidity (ref: 1,2,3,4), kyphosis (ref: 2)

– Increased work of breathing

• Decreased forced total lung capacity, vital capacity, FEV11,3

• Decreased inspiratory, expiratory force (ref: 1,2)

• Diminished respiratory muscle strength (↓25%) (ref: 1,4)

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Pulmonary Changes

• Premature closure of terminal airways (ref: 3)

– V-Q mismatch (ref: 2,3)

– Decrease in PaO2 controversial (ref: 3,4)

• Expected PaO2= 100 – 0.325 x age

– Increased A-a gradient (ref: 1,3)

• Expected P(A-a)O2 = (age +10) x 0.25

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Pulmonary Changes

• Blunted Ventilatory control (ref: 2,3)

– Diminished response to hypoxia (↓50%)

– Diminished response to hypercapnia (↓40%)

• Reduced cough, mucociliary clearance (ref: 2,3)

• Impaired pulmonary immunity (ref: 2,3)

• Diminished gag (ref: 3)

• Difficulty swallowing (ref: 2,3)

– Increased risk of aspiration

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Cardiopulmonary Summary

Cardiopulmonary BASICS:

• Decreased cardiac and respiratory reserves can lead to rapid decompensation in older adults and slower response time in correction

• Pulmonary insult (pneumonia) can trigger heart failure exacerbation

• Acute respiratory failure can result from hemodynamic shock

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Renal Changes

• Decreased creatinine clearance (CC), decreased GFR (ref: 1,2,3)

– Cockroft-Gault Estimated CC = (140-age) x wt(kg)/72 x serum creatinine

– Adjust medication dosage based on estimated CC, not serum creatinine!

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Renal Changes

• Concealed renal insufficiency (ref: 2)

– Reduced GFR despite NORMAL serum creatinine

– May be due to increased prevalence of hypertension, diabetes in elderly

– Present in 13.9% of elderly patients

– Associated with increased risk of adverse reaction with hydrophilic medications

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Renal Changes

• Loss of nephrons (0.5-1%/year) (ref: 2,3)

• Reduced renal plasma flow (10%/decade) (ref:1,2,3)

• Reduced concentrating ability of medullary nephrons (ref: 1,2,3)

• Less responsive to ADH (ref: 2,3)

– More free water loss→ dehydration, electrolyte imbalance (hyperkalemia, hyponatremia)

– Thiazide-induced hyponatremia common in older adults

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Nutrition

• Protein-calorie malnutrition is common in older adults at admission and may develop quickly during hospitization (ref: 1,2,3)

• Diminished muscle mass→ hospital malnutrition→ further weakness (ref: 2,3)

• Increased mortality in underweight older adults (ref: 3)

• Low albumin, pre-albumin associated with increased post-op mortality in older adults

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Nutrition

• Assess nutritional status in all older adults:

– pre-albumin

– transferrin

– indirect calorimetry

– CRP: marker of inflammation, inverse relationship with pre-albumin

• Nutritional support should begin within 24h of ICU admission (ref: 2)

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Medications

• Adverse drug reaction is the most common iatrogenic disorder in older adults (ref: 3)

• Age is an independent risk factor for adverse drug interaction2

• Increased body fat (25-50%), decreased body water in older adults (ref: 1,3)

– Hydrophilic drugs (digoxin, theophylline) have lower volume of distribution—reach higher levels faster

– Lipophilic drugs (psychotropics) have larger volume of distribution—progressive accumulation

• Impaired drug excretion (renal, hepatic) (ref: 3)

• EFFECT: increased half-life, longer duration of action of many medications (ref: 3)

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Medications

• Reduced serum albumin→ higher free drug levels→ greater pharmacologic effect (ref: 3)

• Decreased cytochrome p450 activity→ reduced elimination (especially warfarin, theophylline) (ref: 3)

• Altered sensitivity of receptors to commonly used medications (ref: 3)

– More sensitive: warfarin, narcotics, sedatives, anticholinergics

– Less sensitive: β-adrenergic agonists/antagonists

• Polypharmacy (ref: 2,3)

– Probability of adverse drug interaction:

• 7% if on >5 medications, 24% if on >10 medications

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Medications

• Drugs most often associated with adverse reactions (ref: 2):

– Digitalis

– ACE-I

– Hypoglycemics

• Contrast-induced nephrotoxicity- increased in older adults (ref: 2)

– Ensure preventative measures are taken when using contrast studies!

• When starting medications: Start low, go slow!

– Especially with sedatives and anti-psychotics!

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Delirium

• Seen in 1/3-1/2 of hospitalized older adult patients (ref: 2,3)

• Up to 70% of older adults in ICU (ref: 2,3)

• Can lead to loss of mobility, atrophy, contractures, pressure ulcers, falls, thromboembolism, incontinence, anorexia, constipation, de-motivation (ref: 3)

• Associated with prolonged hospitalization, nursing home placement, increased mortality (ref: 2,3)

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Delirium

• Predisposing factors: (ref: 2,3)

– Prior cognitive impairment: patients with dementia are 5x more likely to develop delirium!

– Structural brain disease

– Chronic illness

– Sleep deprivation

– Drug/alcohol use

– Unfamiliar surroundings/social isolation

• Use of sedatives, psychotropics, restraints can worsen symptoms, increase risk of aspiration, ulcers, etc. (ref: 3)

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Delirium

• Indicative of diffuse brain dysfunction (ref: 3)

• Associated with four disease classes: (ref: 2,3)

– Primary cerebral disease (infection, tumor, stroke, dementia)

– Systemic illness (infection, cardiac, pulmonary, hepatic, uremia, endocrine)

– Intoxication (EtOH, drugs, toxins)

– Withdrawal (EtOH, benzodiazepine, barbiturates)

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Delirium

• Prevention,Treatment (ref: 2,3)

– Identify underlying cause!

– Minimize offending medications

• neuroleptics, opioids, anticholinergics, sedatives, H2-blockers

– Constant observation, minimize restraints!

– Well-lighted, predictable environment

– Eyeglasses, hearing aids, dentures

– Frequent reorientation by staff and family

– Establish normal sleep-wake cycle

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Postoperative Cognitive Dysfuntion(POCD)

• Acute, short-term disorder of cognition, memory, attention following surgery (ref: 2)

• Present in 26% non-cardiac surgery older adults at 1 week post-op, 9.9% at 3 months (ref: 2)

• Present in 80% of older adults after cardiac surgery by discharge, 50% at 6 weeks post-op (ref: 2)

• May be first sign of hypoxemia, sepsis, electrolyte imbalance! Usually idiopathic (ref: 2)

– Suspected interaction between anesthesia and age-related change in neurotransmitters (ref: 2)

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POCD

• Prognosis

– Good: transient symptoms in most sufferers (ref: 2)

– Prolonged POCD: may last months→ years (ref: 2)

• Risk factors

– AGE! (ref: 2)

– Also: duration of anesthesia, post-op infection, respiratory complicaions (ref: 2)

– Age is the only risk factor for prolonged POCD (ref: 2)

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Pressure Ulcers

• Associated with immobility in older adults

• 50% pressure ulcers occur in those >70yo (ref: 3)

• Sites:

– sacrum, ischial tuberosities, hip, heel, elbow, knee, ankle, occiput

• Found in 28% of those confined to bed or chair for 1 week (ref: 3)

• High mortality

– 73% mortality if develops in first 2 weeks of hospitalization (ref: 3)

– May lead to sepsis→ 60% mortality if ulcer is cause (ref: 3)

• Now considered a “never event”- no reimbursement

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Pressure Ulcers

• Prevention

– Frequent repositioning: q2 hours (ref. 3)

– Avoid pressure on bony prominences (ref. 3)

• Rest back on pillows at 30-degree angle from bed

– Head of bed not more than 30 degrees (ref. 3)

– Do not tuck sheets at foot of bed (ref. 3)

• Allow feet to assume natural position

• Protect heels by elevating feet with pillows

– Lift patients to move, do not drag (ref. 3)

– Pat skin dry, do not rub (ref. 3)

– Reduce contact with soilage (fecal, urinary incontinence) (ref. 3)

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Pressure Ulcers

• Prevention

– Ensure adequate nutrition, hydration, pain control (ref. 3)

– Early mobilization (ref. 3)

– Rehab service consult (ref. 3)

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Outcomes

• Age is associated with progressive risk of ICU death2

– Mortality: 36.8% in >65yo; 14.8% <45yo (ref. 2)

– 1-year post-ICU survival: 47% in ≥65yo, 83% <35yo (ref. 2)

age ICU survival 3-mo survival

<75 80%

75-79 68% 54%

80-84 75% 56%

≥85 69% 51%

From: Somme et al. Intensive Care Med 2003: 29:2137-2143

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Outcomes

• Octegenarian hospital survivors discharged to subacute facility have higher mortality compared to those discharged to home (31% vs. 17%) (ref. 2)

• Likelihood of discharge to subacute facility directly related to preadmission comorbidities (ref. 2)

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Optimizing ICU Use

GOAL: Minimize misery, maximize dignity

• ICU care should provide temporary physiologic support for reversible conditions (ref. 2)

• Decision to admit older adults should be based on: patient comorbidities, acuity of illness, prior functional status, patient’s wishes (ref. 2)

• Always clarify and document advanced directives and wishes for intubation, CPR, vasoactive medication

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References

1. Nagappan R, Parkin G. Geriatric critical care. Crit Care Clin 2003:253-270.

2. Marik, PE. Management of the critically ill geriatric patient. Crit Care Med 2006; 34(9):S176-S182.

3. Dhanani S, Norman DC. Chapter 19. Care of the elderly patient. In: Bongard FS. Current diagnosis and treatment critical care. 3rd ed. New York: McGraw-Hill;2008.

4. Delerme, A, Ray P. Acute respiratory failure in the elderly: diagnosis and prognosis. Age and Aging 2008;37:251-257.