ELDERLY PATIENTS

Dr Masood EntezariAsl

Introduction

The use of health care resources, including surgical services, is disproportionately higher in the elderly than in their younger counterparts

Many elderly patients who were denied surgical treatment in the past because of their age now routinely undergo operative procedures as a result of improvement in anesthetic, surgical, and medical care

Approximately 35% of all surgical procedures arc performed in elderly patients

NORMAL PHYSIOLOGIC CHANGES

WITH AGING Functional and structural changes occur

in most of the organ systems with aging (Table)

The rate of aging varies in these organ systems and is influenced by genetic factors, environment, and diet

Cardiovascular System Aging in healthy individuals affects the peripheral

vasculature through increases in wall thickness and the diameter and vascular stiffness of the aorta and large arteries

Systolic and mean arterial blood pressure increases with widening of the pulse pressure

Aortic impedance and systemic vascular resistance increase, and there is a decrease in β-adrenergic-mediated vasodilatation of the systemic vasculature

Aging also affects the heart through increases in left ventricular wall thickness secondary to enlargement of cardiac myocytes

Myocardial compliance is decreased, with a reduction in the early diastolic filling rate and compensatory augmentation of the contribution of atrial contraction to late left ventricular filling

Ventricular diastolic dysfunction, with prolonged relaxation, should be considered in any elderly patient who has a history of decreased exercise tolerance

Despite the common belief that systolic cardiac function decreases with age, it is recognized that in the absence of coexisting cardiovascular disease, resting systolic cardiac function is well preserved, even at very advanced ages

Other cardiovascular-related changes in aging include sclerosis and calcification of the cardiac conduction system and thickening of the aortic valve cusps

Turbulent blood flow caused by thickening of the aortic valve cusps results in the midsystolic ejection murmur that is commonly present in elderly individuals

In addition, the incidence of aortic stenosis increases with aging secondary to cusp calcification because of mechanical wear and tear on the collagenous core of the valve cusp

Pulmonary System

With aging, the central airways increase in size with a resultant increase in the anatomic and physiologic dead spaces

Small airways decrease in diameter secondary to loss of connective tissue support

However, total airway resistance is unchanged, possibly because of opposite changes in the distal and proximal airways

There is a progressive loss in elastic tissue and an increase in the amount of collagen within the lung parenchyma

Lung elastic recoil and tethering support of the small airways are both reduced with consequent dilatation of respiratory bronchioles and alveolar ducts

This results in an approximately 15% reduction in the functional alveolar surface area available for gas exchange by the age of 70 years

Chest wall compliance decreases with aging Decreased intervertebral space and age-

associated kyphoscoliosis lead to decreased chest height and increased anteroposterior diameter, which may alter respiratory mechanics

Respiratory muscle strength decreases with aging secondary to multiple factors such as selective denervation of skeletal muscle fibers and atrophy and degeneration of motor nerves and muscle fibers

Static and dynamic lung volumes also undergo age related changes

The loss of elastic elements results in increased lung compliance and residual volume

As a result, functional residual capacity (FRC) is increased, though to the lesser degree than residual volume, because the decrease in chest wall compliance in part counteracts the decrease in lung recoil

In contrast, total lung capacity decreases minimally, mainly secondary to a decrease in inspiratory muscle strength and a loss of height

Vital capacity declines progressively with aging because of decreases in chest wall compliance, loss of lung elastic recoil, and decreases in respiratory muscle strength

As a result of loss of tethering support of the small airways, closing volume and closing capacity increase

Closing capacity approaches or exceeds FRC, and the decreased ability of elderly individuals to keep the airways open during expiration and to reopen collapsed alveoli during inspiration results in an increase in ventilation-to perfusion mismatching

Although closing capacity and closing volume increase during general anesthesia, the deterioration in arterial oxygenation during general anesthesia is more related to the development of atelectasis in the dependent lung areas with the formation of a shunt, changes that have not been reported to be influenced by aging

Airway reflexes are more sluggish in elderly patients secondary to diminished laryngeal and pharyngeal responses

The cough reflex is less efficient, and the risk for pulmonary aspiration is increased

Gastrointestinal System

The swallowing and motility function of the esophagus and the gastric emptying time are usually unchanged with aging

Liver size decreases progressively with aging, and it is estimated that by the age of 80 years, liver mass is decreased by 40% with a parallel decline in hepatic blood flow

However, the content of both microsomal and nonmicrosomal liver enzymes is unchanged with aging

Liver function test results are generally normal

Renal System The kidneys lose approximately 50% of their functional glomeruli

with similar decreases in renal blood flow by 80 years of age The decline in both renal mass and renal blood flow occurs

primarily in the cortex with compensatory changes in the juxtamedullary region

The glomerular filtration rate is decreased by 30% at 60 years of age and by 50% at 80 years of age

In addition, elderly individuals have a decreased ability to dilute and concentrate urine and to conserve sodium

The decrease in renal function with aging may affect the pharmacokinetics (prolonged elimination half-times) of certain drugs used in anesthesia

The overall decline in renal functional reserve usually has no effect on an elderly individual's ability to maintain extracellular fluid volume and electrolyte concentrations

Similarly, serum creatinine remains relatively stable because of a parallel decrease in overall skeletal muscle mass

However, in situations in which renal blood flow is compromised, the decreased renal functional reserve characteristic of elderly individuals may increase the risk for perioperative renal insufficiency or failure

Central Nervous System Aging is associated with a progressive loss of neural tissue

and a parallel reduction in cerebral blood flow and cerebral oxygen consumption

On average, 30% of total brain mass is lost by 80 years of age

In addition, the number of neuroreceptors generally declines with aging in various regions of the central nervous system

For example, a reduction is seen in the number of serotonin receptors in the cortex, acetylcholine receptors in multiple brain regions, and dopamine receptors in the neostriatum

Levels of dopamine in the neostriatum and substantia nigra are also decreased

These structural changes are not necessarily associated with a decline in cognitive function

However, the incidence of postoperative delirium and cognitive dysfunction is higher in elderly individuals

Patients with a history of cognitive impairment are at even higher risk for further impairment postoperatively

Pharmacokinetic and Pharmacodynamic Changes The pharmacokinetics of drugs is

influenced by changes in : - plasma protein binding - the percentage of body content

that is fat or skeletal muscle (lean mass)

- circulating blood volume - metabolism and excretion of drugs

PROTEIN BINDING

With aging, protein binding sites are reduced secondary to both quantitative (decreased level of circulating protein) and qualitative changes

In addition, elderly individuals frequently take multiple medications that might interfere with the binding of drugs to protein active sites (Table)

These changes may increase the level of free, unbound drug in plasma with a resulting enhanced pharmacologic effect

Drugs Often Taken by Elderly Patients That May Contribute to Adverse Effects or Drug Interactions

LEAN AND FAT BODY MASS

Older individuals have decreased skeletal muscle mass and an increased percentage of body fat

These changes result in an increased ability to store lipid-soluble drugs, which may lead to a more gradual and prolonged release of the drugs used during anesthesia from lipid storage sites and, consequently, an increased elimination time and prolonged effect

CIRCULATING BLOOD VOLUME Circulating blood volume generally

decreases with aging and results in a higher than expected initial plasma drug concentration for the same amount of drug administered

Gradual declines in hepatic and renal function may lead to decreased metabolism and prolonged elimination of drugs and their metabolites and thus may contribute to a more gradual decline in plasma drug concentrations and a prolonged effect of anesthetic drugs

BasaL MetaboLic Rate

The basal metabolic rate declines with aging, and elderly surgical patients may have difficulty maintaining normothermia during general anesthesia

The development of hypothermia may lead to slower metabolism and excretion of drugs in elderly patients

Furthermore, hypothermia may lead to shivering, which will increase the basal metabolic rate and oxygen consumption and result in arterial hypoxemia or myocardial ischemia, or both

Endocrine Changes Endocrine changes occur with aging The response of arginine vasopressin (formerly known as

antidiuretic hormone) to hypovolemia and hypotension is reduced, but it remains sensitive to changes in serum osmolarity

The renal tubules are less sensitive to this hormone and atrial natriuretic peptide

During hyperglycemia, insulin release is impaired However, because of increased peripheral tissue resistance and

decreased clearance, plasma insulin levels are elevated, which results in an enlarging fat depot

Serum levels of renin and aldosterone decline, and the response of both hormones to sodium restriction and postural changes is blunted, with a decreased ability conserve sodium and excrete potassium

In contrast, adrenocorticotropic hormone, cortisol, catecholamine production by the adrenal medulla, and thyroid-stimulating hormone and thyroxine levels are unchanged with aging

PR-EOPERATIVE EVALUATION ANDANESTHETIC CONSIDERATIONS

The prevalence of coexisting diseases increases with aging (Table)

In older individuals undergoing surgery, the most common coexisting diseases are systemic hypertension, diabetes mellitus, cardiovascular disease, pulmonary disease, neurologic disease, and renal disease

Optimizing the patient's medical condition before surgery is essential because baseline health status is an important predictor of postoperative complications

However, for elderly patients, delaying surgery to optimize a medical condition must be weighed against the risk of delaying surgery because emergency surgical treatment is associated with higher morbidity and mortality

Furthermore, delaying certain surgical procedures, such as cancer surgery, may substantially alter the patient's prognosis

In this regard, communication among the anesthesiologist, surgeon, and primary care physician is critical to developing an optimal plan regarding the timing of each elderly patient's surgery

Age-Related Concomitant Diseases in Elderly Patients

Laboratory Testing

Data suggest that routine laboratory testing should not be performed simply on the basis of age alone but, rather, it should be based on a thorough preoperative evaluation to determine coexisting medical conditions and on the type of planned surgical procedures

This approach is likely to be more cost-effective than routine testing in all elderly patients

ELECTROCARDIOGRAM

Elderly patients with a history of coronary artery disease may benefit from a preoperative 12-Jead electrocardiogram (ECG) to determine the presence and location of any previous myocardial infarction, left ventricular hypertrophy, conduction abnormalities, and ST-T wave changes indicative of ischemia

If an abnormality is present, comparison with a previous ECG is needed to determine the timing of the occurrence

However, in elderly patients, abnormalities on the preoperative ECG are common and of limited value in predicting postoperative cardiac complications in noncardiac surgery

The low specificity of the preoperative ECG in predicting postoperative cardiac complications also suggests that a normal ECG does not rule out occult cardiac disease

CHEST RADIOGRAPH

In patients undergoing high-risk surgery, a chest radiograph may be useful in providing noninvasive information regarding ventricular function (cardiomegaly may indicate an ejection fraction <40%)

The pulmonary vasculature should also be examined to rule out preoperative congestive heart failure

However, the cost-effectiveness of routine preoperative chest radiographs in elderly patients undergoing surgery has not been defined

EVALUATIONOF CARDIAC STATUS Because the prevalence of

cardiovascular disease increases with aging, evaluation of cardiac status is an integral part of the preoperative evaluation of elderly patients

Blood Pressure Control

Systemic hypertension (systolic blood pressure ≥180 mm Hg, diastolic blood pressure ≥1l0 mm Hg) increases the risk for cardiac and cerebrovascular disease

Adverse intraoperative events in hypertensive patients include perioperative myocardial ischemia, cardiac dysrhythmias, and cardiovascular lability

Although data are limited, there is little evidence of increased perioperative cardiac risk if systolic blood pressure is less than 180 mm Hg or diastolic blood pressure is less than 110 mm Hg

Even though there is no evidence that deferring anesthesia and surgery reduces peri operative risk, careful determination of the baseline blood pressure range for each patient is critical and requires more than one measurement preoperatively

If systemic blood pressure is consistently elevated, optimization with appropriate antihypertensive drugs preoperatively is often recommended for elective surgery

Checking compliance with blood pressure medication is important because elderly patients frequently take multiple medications, and therefore preoperative instructions on which medications to discontinue need to be carefully conveyed

In patients scheduled for urgent or emergency surgery with a preinduction systolic blood pressure higher than 180 mm Hg or diastolic blood pressure higher than 110 mm Hg, induction of anesthesia may proceed carefully, often with invasive monitoring

In these patients, administration of a small dose of an anxiolytic drug before induction of anesthesia may result in more gradual lowering of systemic blood pressure

In elderly patients with uncontrolled systemic hypertension who are about to undergo emergency surgery, the use of continuous invasive blood pressure monitoring and postoperative surveillance in the intensive care unit may be indicated

Protection from Perioperative Myocardial Ischemia Postoperative myocardial ischemia is the strongest clinical

predictor of adverse postoperative cardiac events in high risk surgical patients, with most ischemic events occurring within the first 24 hours after surgery

Therefore, reducing the number and duration of perioperative ischemic events by improving the myocardial oxygen supply demand balance during surgery may potentially improve postoperative cardiac outcomes

Reduction of myocardial metabolic oxygen demand can be achieved by perioperative administration of β-blockers to decrease myocardial contractility and heart rate

Elderly patients (≥ 65 years of age) who have one or more risk factors (systemic hypertension, current smoking, hypercholesterolemia, diabetes mellitus) may benefit from prophylactic perioperative β-blockade as evidenced by decreased circulating levels of troponin I

However, in elderly patients at low risk for ischemic heart disease, this prophylactic therapy may be potentially costly and unnecessary

Because sympathetic nervous system tone is increased with aging, administration of β-blockers during the peri operative period may result in hypotension, especially in the presence of relative hypovolemia secondary to preoperative fasting

Furthermore, autonomic control of hemodynamics in the elderly may be compromised as a result of the decrease in baroreceptor reflex activity with aging

Because perioperative tachycardia is one of the most important hemodynamic abnormalities that has been shown to be associated with myocardial ischemia, the adequacy of the heart rate response to β-blockers is critical to guide therapy

Individualized dosing of β-blockers for control of postoperative myocardial ischemia rather than a fixed-dose regimen may be more beneficial because patients with coronary artery disease have different coronary anatomy and therefore different ischemic thresholds

Physical Examination

Elderly individuals are more likely to be edentulous, and although removal of dentures preoperatively may facilitate direct laryngoscopy and tracheal intubation, positive pressure ventilation by facemask may be difficult

Range of neck motion should be evaluated because older individuals may have limitations as a result of degenerative spine disease

Auscultation of the carotid arteries over the neck bilaterally is helpful to rule out carotid artery disease but requires confirmation by carotid ultrasound if loud carotid bruits are present

Auscultation of the heart may reveal additional heart sounds such as S₃ or S₄ which are commonly associated with decreased left ventricular compliance

A midsystolic ejection murmur is often present in elderly patients secondary to thickening of the aortic cusps or calcification, or both

A laterally displaced point of maximal impulse together with increased heart size on the chest radiograph suggests cardiomegaly

Auscultation of the lungs is performed to evaluate the presence of rales or wheezes, which may be associated with congestive heart failure or lung disease (or both)

Examination of the extremities should be performed to rule out the presence of peripheral edema, which may be indicative of congestive heart failure

Risk Assessment Although elderly patients are at increased risk for perioperative

morbidity and mortality, advanced age by itself is not a contraindication to surgery

General factors that should be evaluated when performing a preoperative risk assessment include age, functional status, cognition, nutrition, and comorbid conditions (cardiac, pulmonary, renal, and endocrine disease)

When both age and comorbidity are considered, the latter is a better predictor of adverse postoperative outcomes

Functional limitation increases perioperative risk, and preoperative evaluation of functional status with common measures such as activities of daily living and instrumental activities of daily living is informative (Table)

Preoperative cognitive status has been shown to be associated with adverse postoperative outcome and functional recovery, thus emphasizing that assessment of preoperative baseline cognitive status may be useful

Depression is also common in elderly patients and may increase peri operative morbidity, including postoperative delirium

Activities of Daily Living and Instrumental Activities of Daily Living

Management of Preoperative Medication

Elderly patients are typically taking multiple prescription and over-the-counter medications

In general, all antihypertensive and cardiac medications should be continued until surgery, with the exception of diuretics, which are preferably withheld on the day of surgery because the patient will be fasting before surgery

For those taking aspirin or warfarin for treatment of cerebral vascular or coronary artery disease, atrial fibrillation, or deep vein thrombosis, the risks associated with discontinuing anticoagulation should be weighed against the benefits of reduced bleeding from discontinuation of such drugs

Warfarin is typically withheld (often four doses) to allow normalization of the international normalized ratio(INR)

In case of emergency surgery, fresh frozen plasma(FFP) or vitamin K can be administered to reverse warfarin's effects

For patients at high risk for thromboembolism, such as those with a prosthetic heart valve, a history of pulmonary embolism, or a recent history of deep vein thrombosis, a transition using low-molecular-weight heparin or intravenous heparin is indicated when oral anticoagulation is discontinued

Antibiotic prophylaxis is indicated for patients with valvular heart disease and mitral valve prolapse

INTRAOPERATIVE MANAGEMENT

No single anesthetic drug or technique has been demonstrated to be superior for elderly surgical patients

However, familiarity with the pharmacokinetics of anesthetic drugs and how age-related changes may affect drug dosing is important

Adjustments of Anesthetic and Adjuvant Drugs in Elderly Patients

Inhaled Anesthetics

The minimum alveolar concentration (MAC) for various inhaled anesthetics is reduced by approximately 6% per year after the age of 40 years

The onset of action of volatile anesthetics may be more rapid if cardiac output is reduced, particularly for more lipid-soluble drugs, but decreased lung function secondary to an increased shunt fraction has an opposite effect

Recovery from the depressant effects of volatile anesthetics may be more prolonged because of an increased volume of distribution secondary to increased body fat and decreased pulmonary gas exchange

Intravenous Anesthetics and NeuromuscularBlocking Drugs

Dose requirements for barbiturates, opioids, and benzodiazepines are likely

to be decreased in elderly patients

OPIOIDS

The elimination half-time of fentanyl is longer in elderly patients than younger patients because of the larger volume of distribution

As a result, depression of ventilation and prolonged analgesia may ensue with the same dose administered to younger patients

Decreased hepatic clearance may contribute to prolonged opioid effects, especially when high does of these drugs are administered to elderly patients

PROPOFOL

Propofol is highly lipid soluble and produces rapid loss of consciousness when administered intravenously

A decreased induction dose or slow titration is recommended for elderly patients

A decrease in age-related clearance of propofol may result in reduced anesthetic requirements with aging

Propofol, because of its negative inotropic and vasodilatory effects, may give rise to exaggerated decreases in systemic blood pressure when used for induction of anesthesia in elderly patients

Despite these characteristics, propofol may be superior to thiopental for recovery of mental function

ETOMIDATE

Etomidate produces rapid loss of consciousness and has been frequently chosen for induction of anesthesia in elderly patients with cardiovascular instability

The initial volume of distribution of etomidate is decreased such that an 80-year-old patient requires less than half the dose of etomidate to produce the same magnitude of depression on the electroencephalogram as in younger patients

MIDAZOLAM

Midazolam has increased potency and decreased clearance in elderly individuals

Context-sensitive half-times are prolonged

Accordingly, doses of midazolam should be decreased and a longer duration of action is expected

NEUROMUSCULAR BLOCKING DRUGS

Despite age-related changes in the neuromuscular junction, the effects of depolarizing and nondepolarizing neuromuscular blocking drugs are not altered in elderly patients

Rather, the altered pharmacokinetics of these drugs in older individuals is secondary to decreases in renal and hepatic function and the altered volume of distribution that accompanies aging

Clearance is decreased for nondepolarizing neuromuscular blocking drugs (vecuronium, rocuronium) that are dependent on either the kidneys or the liver for elimination from plasma

The duration of action of atracurium and cisatracurium is not prolonged because these drugs are eliminated by Hofmann degradation, which is independent of renal and hepatic clearance mechanisms

Monitoring of neuromuscular function and recovery is important in elderly patients because incomplete recovery of neuromuscular function may lead to a higher incidence of postoperative pulmonary complications

Regional Anesthesia

Cardiovascular responses to either spinal or epidural anesthesia may be exaggerated in older individuals

The decrease in cardiac output is thought to primarily be due to a decrease in stroke volume

Treatment of the resultant hypotension typically consists of the administration of crystalloid solutions or vasopressors such as phenylephrine

Surgical procedures that are amenable to regional anesthesia include transurethral resection of the prostate(TURP), orthopedic procedures such as hip or knee replacement, inguinal herniorrhaphy, and minor gynecologic procedures

Technical difficulties in performing regional anesthesia probably reflect age-related decreases in the intervertebral spaces and scoliosis

A thorough examination of the targeted spinal segment must be performed before initiating regional anesthesia

Intraoperative Monitoring Because of the prevalence of coexisting

disease involving the cardiac and pulmonary systems, consideration should be given to using invasive monitoring such as arterial and central venous catheterization in elderly patients undergoing major surgical procedures, which are likely to be prolonged and include large body fluid shifts

Postoperative Pain Therapy The concept that pain perception decreases

with aging and that elderly individuals have a low tolerance of opioids is unsubstantiated

Elderly individuals are commonly afflicted with osteoarthritis disease that results in chronic pain, which may influence requirements for postoperative pain medications

In addition, because elderly surgical patients have an increased likelihood of postoperative delirium or cognitive dysfunction, or both, assessment of the adequacy of postoperative pain control may be difficult

STRATEGIES TO IMPROVE PERIOPERATIVEMANAGEMENT AND POSTOPERATIVEOUTCOME

Decreasing Cardiovascular Complications

Cardiovascular complications (cardiac dysrhythmias, myocardial ischemia, congestive heart failure)may influence postoperative outcomes in elderly patients

Perioperative planning includes: (1) identifying elderly patients who are at higher

risk for postoperative cardiovascular complications

(2) optimizing preoperative medical therapies (3) modifying known risk factors preoperatively

(pharmacologic therapy( (4) planning of postoperative care (pain control,

admission to intensive care units)

Assessment of Cardiac Function Congestive heart failure is a common

problem in the elderly population It is estimated that congestive heart failure

will develop in 10% of persons 80 years and older and will lead to increased mortality within 2 years

Because clinical signs or a history of congestive heart failure is associated with postoperative cardiac complications, special attention should be directed to preoperative optimization of heart function in elderly surgical patients

DIAGNOSIS OF CONGESTIVE HEART FAILURE Clinical diagnosis of congestive heart

failure can be particularly challenging in elderly patients because of the lack of typical symptoms and physical findings

When present, symptoms of congestive heart failure are often nonspecific and frequently misdiagnosed as symptoms of concomitant disease (chronic pulmonary disease) or interpreted as changes associated with aging

DIASTOLIC CONGESTIVE HEART FAILURE

Despite the common preservation of left ventricular systolic function, congestive heart failure may result from left ventricular diastolic dysfunction

Patients with diastolic congestive heart failure have a leftward shift in the pressure-volume relationship such that their hearts operate on the steep portion of the curve (Fig)

Small changes in volume may result in substantial increases in diastolic pressure to the extent that pulmonary congestion may occur, even at relatively normal left ventricular volume

Such changes may be accentuated by exercise, and many elderly individuals with diastolic dysfunction exhibit exercise intolerance as one of their major symptoms

Other symptoms may include dyspnea, cough, edema, or fatigue

Preoperatively, noninvasive approaches to diagnosing diastolic dysfunction include Doppler echocardiography and radionuclide ventriculography

With Doppler echocardiography, measurement of the ratio between the peak early filling wave (E wave) and the atrial filling wave (A wave) is a useful screening tool for detecting abnormal left ventricular relaxation (Fig)

Disorders associated with diastolic dysfunction include systemic hypertension, coronary artery disease, cardiomyopathies, diabetes, chronic renal disease, aortic stenosis, and atrial fibrillation

Potentially reversible causes of diastolic congestive heart failure in elderly patients include myocardial ischemia and accelerated hypertension

Perioperative goals in elderly patients with diastolic dysfunction include :

(1) maintenance of normal sinus rhythm and a slow heart rate

(2) control of systemic blood pressure (3) optimization of blood volume (4) detection and treatment of myocardial

ischemia The use of invasive monitoring such as central

venous pressure or pulmonary artery catheterization may be indicated in managing patients with a history of congestive heart failure secondary to diastolic dysfunction

Treatment of diastolic congestive heart failure may include pharmacologic interventions (Table)

Pharmacologic Management of Diastolic Dysfunction

Impact of Anesthetic Technique on Cardiovascular Complications The view that regional anesthesia is

better than general anesthesia in reducing adverse cardiac outcomes has not been consistently demonstrated

There is no difference in 30-day mortality in patients undergoing major abdominal surgery with epidural or spinal anesthesia versus general anesthesia

Decreasing Perioperative PulmonaryComplications Advanced age is not considered to be an independent

risk factor for perioperative pulmonary dysfunction In contrast, other factors that have been shown to be

associated with postoperative pulmonary complications include:

(1) emergency surgery (2) anatomic site of surgery (upper abdominal and

thoracic procedures) (3) duration of anesthesia (4) general anesthesia (5) hypercapnia (6) history of smoking (7) obesity (8) preexisting pulmonary disease (COPD and

asthma)

CIGARETTE SMOKING

Cessation of cigarette smoking and the use of oxygen therapy may improve outcomes in patients with COPD

Preoperative cessation of smoking immediately before surgery serves only to decrease carboxyhemoglobin levels (half-time of about 6 hours)

Prolonged cessation of smoking (8 weeks) is necessary to result in a decrease in postoperative pulmonary complications because of the period necessary for improvement in mucociliary action and a decrease in mucus secretion

Differentiation of reversible and irreversible airflow obstruction is important to guide the use of anti-inflammatory medications, β₂-agonists, and anticholinergic agents

ASTHMA

Asthma is often under diagnosed and not optimally treated in elderly individuals

There is a tendency to label elderly patients with symptoms of airflow obstruction as having COPD

Differentiation between asthma and COPD is important because the therapeutic strategies may be different

A post bronchodilator increase in forced exhaled volume in 1 second (FEV1) of200 ml or 15% is considered a sign of reversibility of airflow obstruction and suggests a diagnosis of asthma rather than COPD

However, an overlap between asthma and COPD may be more common in elderly patients because older asthmatics may have a propensity for irreversible airway obstruction and some patients with smoking-related COPD may have some response to bronchodilator therapy

Although pulmonary function tests assess the presence and severity of the disease, they do not have great predictive value for postoperative pulmonary complications

Treatment

Administration of β-agonists is relatively safe in elderly patients, although systemic absorption of inhaled β- agonists may result in tachycardia, systemic hypertension, and skeletal muscle tremors

Patients with asthma may be receiving corticosteroid therapy, which may result in adverse effects such as osteoporosis, psychiatric disturbances, and exacerbation of chronic conditions such as systemic hypertension and diabetes mellitus

Patients being treated with corticosteroids should receive supplemental corticosteroid before induction of anesthesia

Medication such as β- blockers may exacerbate asthma The use of selective β-blockers such as metoprolol or

atenolol is preferable for the treatment of systemic hypertension or congestive heart failure

Intraoperative Management INITIATION OF POSTOPERATIVE PAIN MANAGEMENT: Epidural analgesia with local anesthetics and opioids

provides considerable benefit in terms of pulmonary outcomes after surgery, including :

(1) a decrease in the incidence of atelectasis, pulmonary infections, and

complications (2) better postoperative pain relief than with

parenteral opioids (3) shorter time to tracheal extubation (4) less time in the intensive care unit Indeed, the quality and possibly the modality of

postoperative pain relief may be more important than the choice of intraoperative anesthetic

INTERVENTIONS TO IMPROVE POSTOPERATIVE PULMONARY FUNCTION

Certain intraoperative strategies may improve pulmonary function

Measures such as adding positive end-expiratory pressure (5 to 10 cm H20) can increase FRC and restore the closing capacity-to-FRC ratio

The use of higher inspired oxygen concentrations (FI02) may provide:

(1) a better proinflammatory and antimicrobial response of alveolar macrophages than that associated with30%oxygen

(2) a lower incidence of postoperative nausea and vomiting

(3) a reduced incidence of surgical wound infections A high FI02 does not influence postoperative pulmonary

mechanical dysfunction or alter the incidence of postoperative complications such as pulmonary atelectasis

Reducing Postoperative Delirium Delirium, an acute disorder of attention and

cognition, occurs in 14% to 50% of hospitalized medical patients (especially elderly patients) and is accompanied by a mortality rate ranging from 10% to 65%

In general, delirium is the manifestation or symptom of an underlying medical illness for which multiple causes exist

Delirium can be superimposed on dementia or other neurologic disorders associated with global cognitive impairment

As a result, the course of delirium can vary considerably and depends on resolution of the causative factors

PREDISPOSING FACTORS

Factors that predispose elderly patients to delirium include :

- aging processes in the brain - structural brain disease - a reduced capacity for homeostatic

regulation and therefore resistance to stress - visual and hearing impairment - a high prevalence of chronic disease - reduced resistance to acute diseases - age-related changes in the

pharmacokinetics and pharmacodynamics of drugs

Sleeping disorders, sensory deprivation or overload, and psychological stress resulting from bereavement or relocation to an unfamiliar environment are common precipitants of delirium

Certain drugs administered during anesthesia may be associated with postoperative delirium, but it is not possible to determine whether elimination of these drugs will actually lead to a lower incidence of delirium postoperatively

Controversy persists regarding whether any anesthetic technique (regional versus general) has an impact on postoperative delirium

Earlier studies suggested an association between general anesthesia and a higher incidence of cognitive dysfunction relative to epidural anesthesia

However, recent studies have concluded that there was no relationship between anesthetic technique and the magnitude or pattern of postoperative cognitive dysfunction

Intraoperative hypotension does not appear to influence the occurrence of postoperative cognitive dysfunction

Until more definitive clinical studies become available, minimizing the number of medications used, avoiding arterial hypoxemia and extremes of hypocapnia or hypercapnia, and providing adequate postoperative pain control appear to be the best approach to minimizing the occurrence of postoperative delirium in elderly surgical patients