ELDERLY PATIENTS

DR ABDOLLAHI

REF.CH.14- B

ASIC OF ANESTHEISA

04/21/231

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 are performed in elderly patients.

04/21/232

NORMAL PHYSIOLOGIC CHANGESWITH AGING

Functional and structural changes occur in most of the organ systems with aging. The rate of aging varies in these organ systems and is influenced by genetic factors, environment, and diet.

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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.

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

04/21/238

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.

04/21/239

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.

04/21/2310

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.

04/21/2311

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.

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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.

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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.

04/21/2314

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.

04/21/2315

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.

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

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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.

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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.

04/21/2319

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.

04/21/2320

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.

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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

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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.

04/21/2323

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.

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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, and metabolism and excretion of drugs.

04/21/2325

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

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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.

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CIRCULATINGBLOOD 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.

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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.

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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

04/21/2331

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.

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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 to conserve sodium and excrete potassium

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

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PR-EOPERATIVE EVALUATION AND ANESTHETIC CONSIDERATIONS

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The prevalence of coexisting diseases increases with aging In older individuals undergoing surgery, the most common coexisting diseases are systemic hypertension, diabetes mellitus, cardiovascular disease, pulmonary disease, neurologic disease, and renal disease.

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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.

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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.

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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.

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ELECTROCARDIOGRAM

Elderly patients with a history of coronary artery disease may benefit from a preoperative 12-lead 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.

04/21/2340

However, in elderly patients, abnormalities on the preoperative ECG are common and of limited value in predicting postoperative cardiac complications in no cardiac 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.

04/21/2341

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.

04/21/2342

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.

04/21/2343

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 Jess than 110 mm Hg.

04/21/2344

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

04/21/2345

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.

04/21/2346

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.

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PROTECTION FROM PERIOPERATIVE MYOCARDIALISCHEMIA

Postoperative myocardial ischemia is the strongest clinical predictor of adverse postoperative cardiac events in highrisk surgical patients, with most ischemic events occurring within the first 24 hours after surgery.

04/21/2348

Therefore, reducing the number and duration of perioperative ischemic events by improving the myocardial oxygen supplydemand balance during surgery may potentially improve postoperative cardiac outcomes. Reduction of myocardial metabolic oxygen demand can be achieved by perioperative administration of B-blockers to decrease myocardial contractility and heart rate.

04/21/2349

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 B-blockade as evidenced by decreased circulating levels of troponin. However, in elderly patients at low risk for ischemic heart disease, this prophylactic therapy may be potentially costly and unnecessary.

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Because sympathetic nervous system tone is increased with aging, administration of B-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.

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.

04/21/2352

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.

04/21/2353

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

04/21/2354

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.

04/21/2355

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.

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04/21/2356

In case of emergency surgery, fresh frozen plasma 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.

04/21/2357

INTRAOPERATIVEMANAGEMENT

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.

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INHALED ANESTHETICS

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

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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.

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INTRAVENOUS ANESTHETICS AND NEUROMUSCULAR BLOCKING DRUGS

Dose requirements for barbiturates, opioids, and benzodiazepines are likely to be decreased in elderly patients.

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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.

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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.

04/21/2363

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, propofolmay be superior to thiopental for recovery of mental function.

04/21/2364

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.

04/21/2365

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.

04/21/2366

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.

04/21/2367

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

04/21/2368

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.

04/21/2369

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.

04/21/2370

Surgical procedures that are amenable to regional anesthesia include transurethral resection of the prostate, 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.

04/21/2371

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.

04/21/2372

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 osteoarthritic 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.

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STRATEGIES TO IMPROVE PERIOPERATIVE MANAGEMENT AND POSTOPERATIVE OUTCOME

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DECREASING CARDIOVASCULAR COMPLICATIONS

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

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Perioperative planning includes (I) 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), and (4) planning of postoperative care (pain control, admission to intensive care units).

04/21/2376

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.

04/21/2377

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.

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symptoms may include dyspnea, cough, edema, or fatigue. Preoperatively, noninvasive approaches to diagnosing diastolic dysfunction include Doppler echocardiography and radionuclide ventriculography.

04/21/2379

Perioperative goals in elderly patients with diastolic dysfunction include

(I) 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

04/21/2380

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.

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PHARMACOLOGIC MANAGEMENT OF DIASTOLIC DYSFUNCTION

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IMPACT OF ANESTHETIC TECHNIQUE ON CARDIOVASCULARCOMPLICATIONS

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.

04/21/2383

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

(I)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 (chronic obstructive pulmonary disease [COPD] and asthma).

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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.

04/21/2385

ASTHMA

Asthma is often underdiagnosed 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 postbronchodilator increase in forced exhaled volume in 1 second (FEV,) of200 mL or 15% is considered a sign of reversibility of airflow obstruction and suggests a diagnosis of asthma rather than COPD.

04/21/2386

TREATMENT

Administration of B-agonists is relatively safe in elderly patients, although systemic absorption of inhaled B-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.

04/21/2387

Patients being treated with corticosteroids should receive supplemental corticosteroid before induction of anesthesia. Medication such as B- blockers may exacerbate asthma. The use of selective B-blockers such as metoprolol or atenolol is preferable for the treatment of systemic hypertension or congestive heart failure.

04/21/2388

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; and (4) less time in the intensive care unit.

04/21/2389

INTERVENTIONS TO IMPROVE POSTOPERATIVEPULMONARY 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.

04/21/2390

The use of higher inspired oxygen concentrations (FI02) may provide (I) a better proinflammatory and antimicrobial response of alveolar macrophages than that associated with 30% oxygen, (2) a lower incidence of postoperative nausea and vomiting, and (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.

04/21/2391

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.

04/21/2392

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.

04/21/2393

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.

04/21/2394