Handbook of Clinical Anesthesia
Rare and Coexisting Diseases
A variety of rare disorders may influence the selection and conduct of anesthesia (Table 25-1) (Dierdorf SF, Walton JS: Anesthesia for patients with rare coexisting diseases. In Clinical Anesthesia. Edited by Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC. Philadelphia: Lippincott Williams & Wilkins, 2009, pp 622–643). Anesthesiologists must periodically update their diagnostic skills and clinical knowledge to recognize when additional evaluation or treatment may be required and how these diseases influence the management of anesthesia.
- Musculoskeletal Diseases
Musculoskeletal Diseases are characterized by a progressive loss of skeletal muscle function. (Cardiac and smooth muscle are also affected.)
- Duchenne's muscular dystrophyis caused by a lack of production of dystrophin, a major component of the skeleton of the muscle membrane characterized by painless degeneration and atrophy of skeletal muscle.
- The genetic defect is sex linked (manifests only in males), and symptoms manifest between 2 and 5 years of age (creatine kinase may be increased before symptoms appear). Death is usually secondary to congestive heart failure or pneumonia.
- Axial skeletal muscle imbalance produces kyphoscoliosis,which often requires surgical correction.
- Involvement of cardiac muscle is reflected by a progressive loss of the R-wave amplitude on the lateral precordial leads of the electrocardiogram (ECG). Routine echocardiography can provide important information about cardiac function. Progressive loss of myocardial tissue results in cardiomyopathy, ventricular dysrhythmias, and mitral regurgitation.
Table 25-1 Coexisting Diseases That Influence Anesthesia Management
- Treatment of cardiac dysfunction includes angiotensin-converting enzyme inhibitors, beta-adrenergic blockers, and dysrhythmia surveillance.
- Degeneration of respiratory muscles (reflected by spirometry) results in an ineffective cough with retention of secretions and pneumonia.
- Management of Anesthesia.Significant complications from anesthesia in patients with muscular dystrophy are secondary to the effects of anesthetic drugs on myocardial and skeletal muscle.
- Reports of cardiac arrest associated with rhabdomyolysis and hyperkalemia have occurred with volatile anesthetics alone or in combination with succinylcholine (Sch).
- Susceptibility to malignant hyperthermia is unpredictable.
- It may be prudent to use intravenous anesthetics and avoid volatile anesthetics and Sch for patients with muscular dystrophy.
- Degeneration of gastrointestinal smooth muscle with hypomotility of the intestinal tract and delayed gastric emptying in conjunction with impaired swallowing mechanisms may increase the risk of perioperative aspiration.
- THE MYOTONIASare characterized by delayed relaxation of skeletal muscle after voluntary contraction
owing to dysfunction of ion channels in the muscle membrane.
- Clinical features include diabetes mellitus, thyroid dysfunction, adrenal insufficiency, and cardiac abnormalities (conduction delays, heart block [sudden death], tachydysrhythmias, cardiomyopathy).
- Pulmonary function studies demonstrate a restrictive lung disease pattern, mild arterial hypoxemia, and diminished ventilatory responses to hypoxia and hypercapnia.
- Pregnancy may produce an exacerbation of myotonic dystrophy, and congestive heart failure is more likely to occur during pregnancy.
- Management of Anesthesia
- Sch produces myotonia and should not be administered to these patients. The response of these patients to nondepolarizing muscle relaxants may be enhanced. Reversal with neostigmine may provoke myotonia. The response to the peripheral nerve stimulator must be carefully interpreted because muscle stimulation may produce myotonia (misinterpreted as sustained tetanus when significant neuromuscular block still exists).
- Patients with myotonia are very sensitive to the ventilatory depressant effects of opioids, barbiturates, benzodiazepines, and volatile anesthetics.
- No specific anesthetic technique has been shown to be superior for patients with myotonic dystrophy. Propofol infusions may be acceptable. Inhaled anesthetics may be used, but close monitoring of cardiac rhythm and cardiovascular function is indicated.
- Familial Periodic Paralysis.The familial periodic paralyses are a subgroup of diseases referred to as skeletal muscle channelopathies. The common mechanism for these diseases appears to be a persistent sodium inward current depolarization causing muscle membrane inexcitability and subsequent muscle weakness (Table 25-2).
- Hyperkalemic periodic paralysisis characterized by episodes of myotonia and muscle weakness that may last for hours after exposure to a trigger (Table 25-2).
- Hypokalemic periodic paralysisis caused by a defect in the calcium ion channel (Table 25-2).
Table 25-2 Clinical Features of Familial Periodic Paralysis
- Management of Anesthesia
- The primary goal of the perioperative management of patients with both forms of periodic paralysis is the maintenance of normal potassium levels and avoidance of events that precipitate muscle weakness (alkalosis owing to hyperventilation, carbohydrate loads, hypothermia).
- Short-acting muscle relaxants are preferred, and the response should be monitored with a peripheral nerve stimulator. Sch should be avoided because it may enhance potassium release from skeletal muscle cells.
- The ECG should be monitored for evidence of hypokalemia and associated cardiac dysrhythmias (serum potassium concentration should be measured during prolonged operations).
- Avoidance of carbohydrate loads, hypothermia, and excessive hyperventilation is prudent.
- Myasthenia gravisis an autoimmune disease with antibodies directed against the nicotinic acetylcholine receptor or other muscle membrane proteins (Table 25-3). The majority of patients have abnormalities of the thymus (thymoma, thymic hyperplasia, thymic atrophy).
Table 25-3 Summary of the Different Presentations of Myasthenia Gravis
- The clinical hallmark of myasthenia gravis is skeletal muscle weakness (increased by repetitive muscle use) with periods of exacerbation and remission.
- Neonatal myasthenia begins 12 to 48 hours after birth and reflects transplacental passage of antiacetylcholine antibodies.
- Focal myocarditis and atrioventricular heart block may be present.
- Treatmentincludes administration of anticholinesterase drugs, thymectomy, corticosteroids, and immunosuppressants. Whereas underdosage with anticholinesterase drugs results in skeletal muscle weakness, overdosage leads to a “cholinergic crisis.” The role of thymectomy for the treatment of myasthenia is not clearly established.
- Management of Anesthesia
- The primary concern is the potential interaction between the disease, treatment of the disease, and neuromuscular blocking drugs. Patients with uncontrolled or poorly controlled myasthenia are exquisitely sensitive to even small (defasciculating) doses of nondepolarizing muscle relaxants.
- The variability in response to different muscle relaxants warrants careful monitoring with a peripheral nerve stimulator and its correlation with clinical signs of recovery from neuromuscular blockade. Short- or intermediate-acting non-depolarizing muscle relaxants are usually recommended.
- Myasthenic Syndrome (Lambert-Eaton Syndrome)
- The myasthenic syndrome is a disorder of neuromuscular transmission associated with carcinomas, particularly small cell carcinoma of the lung (this should be suspected in patients undergoing diagnostic procedures, such as diagnostic bronchoscopy, mediastinoscopy, or exploratory thoracotomy for possible cancer) (Table 25-4).
- Management of Anesthesia
- Patients with myasthenic syndrome are sensitive to the effects of both depolarizing and nondepolarizing muscle relaxants.
- Administration of 3,4-diaminopyridine should be continued until the time of surgery.
- Guillain-Barré syndrome (polyradiculoneuritis)is the acute form of a group of disorders classified as
inflammatory polyneuropathies (autoimmune disease caused by a bacterial or viral infection that triggers an immune response, producing antibodies that damage the myelin sheath and cause axonal degeneration).
Table 25-4 Comparison of Myasthenia Gravis and Myasthenic Syndrome
- This syndrome is characterized by the acute or subacute onset of skeletal muscle weakness or paralysis of the legs, which spreads cephalad and may result in difficulty swallowing and impaired ventilation from paralysis of the intercostal muscles.
- The most serious immediate problem is hypoventilation. (Vital capacity should be monitored frequently. If it decreases below 15 to 20 mL/kg, mechanical ventilation of the lungs is indicated.)
- Although 85% of patients with this syndrome achieve a good recovery, chronic recurrent neuropathy develops in 3% to 5% of patients.
- Autonomic nervous systemdysfunction may be associated with wide fluctuations in blood pressure (physical stimulation may precipitate hypertension),
tachycardia, cardiac dysrhythmias, and cardiac arrest.
- Management of Anesthesia
- Compensatory cardiovascular responses may be absent (autonomic nervous system dysfunction), resulting in significant hypotension secondary to postural changes, blood loss, or positive airway pressure. Conversely, stimuli such as laryngoscopy and tracheal intubation may produce hypertension and tachycardia.
- Sch is not recommended because drug-induced potassium release may result in hyperkalemia and cardiac arrest. The response to nondepolarizing muscle relaxants ranges from sensitivity to resistance.
- It is likely that mechanical ventilation is required during the immediate postoperative period.
III. Central Nervous System Diseases
- Multiple sclerosisis characterized by multiple sites of demyelination in the brain and spinal cord, leading to visual disturbances, limb weakness, and paresthesias.
- Therapy for multiple sclerosis is directed at modulating the immunologic and inflammatory responses that damage the central nervous system (CNS) (corticosteroids, interferon, glatiramer, mitoxantrone [maybe cardiotoxic]).
- Management of Anesthesia.The effect of anesthesia and surgery on the course of multiple sclerosis is controversial.
- Regional and general anesthesia have been reported to exacerbate or have no effect on multiple sclerosis. Factors other than anesthesia, such as infection, emotional stress, and hyperpyrexia, may contribute to an increased risk of perioperative exacerbation.
- A neurologic examination before anesthesia and surgery is helpful to document coexisting neurologic deficits.
- Patients being treated with corticosteroids may require perioperative supplementation, and immunosuppressants may produce cardiotoxicity and subclinical cardiac dysfunction.
- Autonomic dysfunction caused by multiple sclerosis may produce exaggerated hypotensive effects in response to volatile anesthetics.
Table 25-5 The Most Frequently Encountered Types of Seizures
- Respiratory muscle weakness and dysfunction may increase the likelihood of the need for postoperative mechanical ventilation.
- Epilepsy(Table 25-5)
- The sudden onset of seizures in a young to middle-aged adult should arouse the suspicion of focal brain disease (tumor); onset after 60 years of age is usually secondary to cerebrovascular disease.
- The availability of new antiseizure drugs has increased the therapeutic options for patients with epilepsy (Table 25-6).
- Management of Anesthesia
- Antiseizure medications should be maintained throughout the perioperative period.
- An anesthetic technique should be used that minimizes the risk of seizure activity. Although most inhaled anesthetics, including nitrous oxide, have been reported to produce seizure activity, such activity during the administration of isoflurane and
desflurane is extremely rare. (Sevoflurane may be eliptogenic, but the clinical significance is uncertain.) Ketamine may produce seizure activity in patients with known seizure disorders. Reported seizure activity after administration of opioids may reflect myoclonic activity.
Table 25-6 Anticonvulsant Drugs
Table 25-7 Clinical Features of Parkinson's Disease
- Parkinson's diseaseis a degenerative disease of the CNS caused by the loss of dopaminergic fibers in the basal ganglia of the brain (occurs in 1% of population older than age 60 years)
- Typical clinical features are secondary to depletion of dopamine from the basal ganglia (Table 25-7).
- Treatment protocols involve combinations of drugs designed to increase dopamine levels in the brain while blunting the peripheral effects of dopamine. The therapeutic regimen for patients with Parkinson's disease is complex and requires a skilled neurologist to individualize therapy.
- The combination of levodopa and carbidopa (which blocks peripheral conversion of levodopa to dopamine) is the most frequent treatment.
- Side effects of levodopa include depletion of myocardial norepinephrine stores, peripheral vasoconstriction, hypovolemia, and orthostatic hypotension.
- Use of surgical pallidotomy (local anesthesia) and implantation of deep brain stimulators may be a good option for selected patients.
- Management of Anesthesia
- Drugs that may antagonize the effects of dopamine in the CNS (droperidol, metoclopramide, and possibly alfentanil) should be avoided.
- Levodopa has a brief half-time, and interruption of therapy for more than 6 to 12 hours may result in skeletal muscle rigidity that interferes with ventilation.
- Success with the use of selegiline for the treatment of parkinsonism increases the likelihood of having to anesthetize a patient who is receiving a monoamine oxidase B inhibitor. (Meperidine should be avoided in these patients.)
- Autonomic dysfunctionis common and manifests as esophageal dysfunction (risk of aspiration) and orthostatic hypotension (exaggerated decreases in blood pressure in response to volatile anesthetics).
- Postoperatively, these patients may develop mental confusion.
- Alzheimer's diseaseis the major cause of dementia in the United States.
- The incidence of Alzheimer's disease is 1% in 60 year olds and 30% in 85 year olds.
- Administration of cholinesterase inhibitors is considered the standard of care for patients with early Alzheimer's disease.
- Management of anesthesiais guided by the patient's general physiologic condition, the degree of neurologic impairment, and the potential for interaction between anesthetics and medications the patient is receiving.
- Sedative drugs for preoperative medication may result in further mental confusion.
- Anesthetics (propofol, desflurane, sevoflurane) known to result in prompt postoperative recovery may be advantageous by permitting a more rapid return to the patient's preoperative state. Although isoflurane may increase amyloid beta protein generation and aggregation in isolated human neurons, the clinical significance is unknown.
- If an anticholinergic drug is required, glycopyrrolate, which does not easily cross the blood–brain barrier, is preferable to scopolamine or atropine, which cross blood–brain barrier and may exacerbate dementia.
Table 25-8 Types of Anemia
- Patients receiving cholinesterase inhibitors may have a prolonged response to Sch.
- Anemias (Table 25-8)
- In an otherwise healthy person, symptoms do not develop from anemia until the hemoglobin level decreases below 7 g/dL. (Physiologic compensation includes increased blood volume and cardiac output and decreased blood viscosity.) There is no universally accepted hemoglobin level that mandates blood transfusion. The patient's physiologic status and coexisting diseases must be factored into this highly subjective decision.
- Nutritional Deficiency Anemias
- Iron deficiency anemiamay be an absolute deficiency caused by decreased oral intake of iron or a relative deficiency of iron caused by a rapid turnover of red blood cells (chronic blood loss, hemolysis). Severe iron deficiency produces microcytic anemia and may result in thrombocytopenia and neurologic abnormalities.
- Vitamin B12deficiency results in megaloblastic anemia and nervous system dysfunction (peripheral neuropathy secondary to degeneration of the lateral and
posterior columns of the spinal cord manifesting as symmetric paresthesias with loss of proprioception and vibratory sensation, especially in the lower extremities). Prolonged exposure to nitrous oxide (inactivates the vitamin B12 component of methionine synthetase) results in megaloblastic anemia and neurologic changes similar to those that occur in pernicious anemia.
- Folic acid deficiency(because of alcoholism, pregnancy, malabsorption [phenytoin, methotrexate]) results in megaloblastic anemia, but peripheral neuropathy is not as common as with vitamin B12 deficiency.
- Hemolytic anemiasreflect premature destruction (before 120 days) of red blood cells.
- Glucose-6-phosphate dehydrogenase (G6PD) deficiencyis the most common enzymopathy in humans. It affects 400 million people worldwide and may confer malarial resistance.
- A deficiency of G6PD results in decreased levels of glutathione when erythrocytes are exposed to oxidants. This increases the rigidity of the red blood cell membrane (hemolysis) and accelerates clearance of erythrocytes from the circulation.
- A number of drugs may enhance the destruction of erythrocytes in patients with G6PD deficiency (Table 25-9). Characteristically, the hemolytic episode begins 2 to 5 days after drug administration.
- Patients with G6PD deficiency are unable to reduce methemoglobin produced by sodium nitrate, so sodium nitroprusside should not be administered in these patients.
Table 25-9 Drugs That Produce Hemolysis in Patients with Glucose-6-Phosphate Dehydrogenase Deficiency
- Anesthetic drugs have not been implicated as hemolytic agents, but early postoperative evidence of hemolysis might suggest G6PD.
- Hemoglobinopathiesare diseases caused by genetic errors in hemoglobin synthesis and production. (These diseases convey survival protection in malaria-endemic areas.)
- Sickle cell disease (SCD)results from mutation of chromosome 11, which causes substitution of valine for glutamic acid. Whereas persons heterozygous for the sickle cell gene (HbSA) are usually asymptomatic, homozygous individuals (HbSS) have SCD.
- Clinical Manifestations(Table 25-10). Acute chest syndrome (dyspnea, wheezing, chest pain, hypoxemia, pulmonary infiltrates) represents the single greatest threat to patients with SCD.
- Treatmentof SCD is supportive and directed at early treatment of complications.
- Management of Anesthesia.Preparation of patients with SCD for surgery should be done in close collaboration with the SCD specialty service that provides the patient's routine care. Prevention of conditions that favor sickling is the basis of perioperative management.
- Supplemental oxygen is recommended during and after regional and general anesthesia.
- Circulatory stasis can be prevented with hydration and anticipation of intraoperative blood loss in order to avoid acute hypovolemia.
- Normothermia is desirable because hyperthermia increases the rate of gel formation, and hypothermia produces vasoconstriction that impairs organ blood flow.
- The use of a tourniquet or preoperative transfusion is controversial.
- Hemoglobin and hematocrit should be measured preoperatively and adequate oxygen-carrying capacity maintained by transfusion to keep the hematocrit near 30%.
- Drugs commonly used for anesthesia do not have significant effects on the sickling process, assuming arterial hypoxemia, vascular stasis, and reduced cardiac output are avoided. Regional anesthesia has been successfully used for surgery, labor and delivery, and pain management.
Table 25-10 Clinical Manifestations of sickle cell disease
Table 25-11 Types of Collagen Vascular Diseases
- Collagen Vascular Diseases (Table 25-11)
- Rheumatoid arthritisis a chronic inflammatory disease characterized by symmetric and significant polyarthropathy (hands and wrists first, cervical spine as reflected by magnetic resonance imaging) and systemic involvement (Table 25-12).
- The goals of therapy are induction of a remission, improved function, and maintenance of a remission. Drugs used for treatment include nonsteroidal antiinflammatory drugs, corticosteroids, and disease-modifying antirheumatic drugs. (Methotrexate may the first-line treatment for patients with early rheumatoid arthritis.)
- Management of Anesthesia
- The joint effects of rheumatoid arthritis (temporomandibular joints, cervical spine, cricoarytenoid joints) can render direct laryngoscopy and tracheal intubation difficult.
- Atlantoaxial instabilityis relatively common, and flexion of the neck may compress the spinal cord.
- The need for postoperative ventilatory support should be anticipated if severe restrictive pulmonary disease is present.
- Restriction of joint mobility necessitates careful positioning to minimize the risk of neurovascular compression.
Table 25-12 Extra-articular Manifestations of Rheumatoid Arthritis
- Systemic lupus erythematosus(SLE) is an autoimmune disease with diverse clinical (polyarthritis, dermatitis, renal failure, pericarditis, pulmonary hypertension) and immunologic manifestations.
- Drug-induced SLE (phenytoin, hydralazine, isoniazid) is usually mild and resolves within 4 weeks of discontinuation of the drug.
- Management of anesthesiais influenced by disease-induced organ dysfunction and drugs used in treatment.
- Renal dysfunction is common and necessitates preoperative evaluation.
- Laryngeal involvement may manifest postoperatively as laryngeal edema or stridor.
- Supplemental steroids may be necessary in patients being treated with corticosteroids.
- Sclerodermais an autoimmune collagen vascular disease that affects the skin (thickened and swollen), joints, and visceral organs (pulmonary interstitial fibrosis and impaired diffusing capacity, pericardial effusion, renal dysfunction, decreased gastrointestinal motility).
- Raynaud's phenomenon occurs in 95% of patients with scleroderma.
- Management of anesthesiais influenced by the degree of organ dysfunction.
- The risk for aspiration pneumonitis during induction of anesthesia may be increased because of the high incidence of gastroesophageal reflux.
- Tracheal intubation may be difficult because fibrotic and taut skin can hinder active and passive opening of the mouth and severely restrict mobility of the temporomandibular joint.
- Chronic arterial hypoxemia may reflect restrictive lung disease and impaired oxygen diffusion.
- Venous access may be difficult.
- Skeletal muscle involvement may increase the sensitivity to muscle relaxants.
- Polymyositis and dermatomyositis (inflammatory myop-athies)are characterized by severe muscle weakness and noninfectious inflammation. Patients with dermatomyositis manifest a characteristic erythematous rash over the face, neck, and upper chest.
- Pulmonary diseases (interstitial pneumonitis, alveolitis, bronchopneumonia) are often present.
- Aspiration pneumonitis (dysphagia and gastroesophageal reflux) is a common complication.
- The most effective treatment is with corticosteroids.
- Management of Anesthesia
- Tracheal intubation may be difficult in patients with restricted joint mobility.
- Despite the theoretical potential for Sch to produce hyperkalemia in these patients, there is no evidence that this occurs.
- It should be anticipated that considerable individual variation will occur in response to nondepolarizing muscle relaxants.
- Skin Disorders
- Epidermolysis bullosais characterized by abnormal collagen that is insufficient for anchoring skin layers to each other. (Laryngeal involvement is rare.)
- Pressure applied perpendicular to the skin is less likely to produce separation of skin layers (intradermal fluid accumulation and bullae formation) than are lateral shearing forces.
- Management of anesthesiais based on avoidance of trauma to the skin and mucous membranes from
adhesive tape, blood pressure cuffs, tourniquets, and adhesive electrodes.
- Lubrication of the face mask is useful for decreasing trauma to the face.
- Use of upper airway instruments and passage of an esophageal stethoscope should be avoided. The safety of tracheal intubation has been established for patients with the dystrophic form of this disease.
- Ketamine is useful anesthesia for superficial surgical procedures.
- Pemphigusis an autoimmune vesiculobullous disease that involves the skin and mucous membranes. Oral lesions are common, and corticosteroids are effective in therapy.
Editors: Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K.; Cahalan, Michael K.; Stock, M. Christine
Title: Handbook of Clinical Anesthesia, 6th Edition
Copyright ©2009 Lippincott Williams & Wilkins
> Table of Contents > Section V - Preanesthetic Evaluation and Preparation > Chapter 26 - The Anesthesia Workstation and Delivery Systems