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Internal Med MKSAP Pulmonary/Critical Care

Terms in this set (49)

* In patients with moderate chronic obstructive pulmonary disease, therapy with a long-acting β2-agonist or a long-acting anticholinergic agent improves quality of life and pulmonary function compared with therapy with short-acting bronchodilators alone.

This patient has stage II chronic obstructive pulmonary disease (COPD) as defined by the guidelines of the Global Initiative for Obstructive Lung Disease (GOLD). GOLD stage II disease is defined by a postbronchodilator FEV1/FVC ratio less than 70% and an FEV1 less than 80% but more than 50% of predicted with or without chronic symptoms. In patients with GOLD stage II disease, maintenance treatment with one or more long-acting bronchodilators such as a long-acting β2-agonist (salmeterol or formoterol) is recommended, along with as-needed albuterol. Pulmonary rehabilitation can be considered in addition to medical treatment in symptomatic patients. Starting or adding a long-acting anticholinergic agent would also be appropriate.

Inhaled corticosteroids, oral corticosteroids, theophylline, and montelukast would be inappropriate for this patient. Theophylline's narrow therapeutic window and poor bronchodilator effect make it a poor choice. Oral corticosteroids are not recommended routinely in COPD because of their systemic side effects. Montelukast is used as a third-line agent in asthma but has not been shown to be efficacious in COPD. The GOLD guidelines recommend consideration of inhaled corticosteroids in patients whose lung function is less than 50% and who experience recurrent exacerbations. When inhaled corticosteroids are combined with a long-acting β2-agonist in such patients, the rate of decline in quality of life and health status is significantly reduced and the frequency of acute exacerbations is reduced by 25%; lung function is also improved and dyspnea alleviated.
* The response to inhaled bronchodilators is more predictive of the clinical course in a patient with asthma than initial physical examination and findings.

This patient presented with signs of a severe asthma exacerbation. Decreased breath sounds, accessory muscle use, sternocleidomastoid or suprasternal retractions, inability to speak in full sentences, and paradoxical pulse greater than 15 mm Hg are associated with severe airflow obstruction, although the absence of these findings does not necessarily exclude the presence of a high-risk exacerbation. However, the initial physical examination and findings are less predictive of the clinical course in a patient with asthma than the response to bronchodilators. This patient has responded well to bronchodilators, with improved ability to speak and reduced accessory muscle use. Wheezing may become more prominent in the early stages of recovery owing to improved airflow through narrowed airways. According to the newest National Asthma Education and Prevention Program's guidelines, admission to the intensive care unit is recommended for symptomatic patients with even mild carbon dioxide retention (PCO2 greater than 42 mm Hg) or severely decreased lung function despite aggressive bronchodilator treatment (persistent FEV1 or peak expiratory flow less than 40% of predicted). This patient does not meet the criteria for admission to the intensive care unit or intubation and mechanical ventilation at this time. The best disposition for this patient would be admission to the hospital ward; his FEV1 has not improved enough to warrant discharge.
* Malignant hyperthermia is an inherited skeletal muscle disorder characterized by a hypermetabolic state precipitated by exposure to volatile inhalational anesthetics and the depolarizing muscle relaxants.

Treatment
DANTROLENE

This patient most likely has malignant hyperthermia, which is an inherited skeletal muscle disorder characterized by a hypermetabolic state precipitated by exposure to volatile inhalational anesthetics (halothane, isoflurane, enflurane, desflurane, sevoflurane) and the depolarizing muscle relaxants succinylcholine and decamethonium. It usually occurs on exposure to the drug but can occur several hours after the initial exposure and can develop in patients who were previously exposed to the drug without effect. Increased intracellular calcium leads to sustained muscle contractions, with skeletal muscle rigidity and masseter muscle spasm, tachycardia, hypercarbia, hypertension, hyperthermia, tachypnea, and cardiac arrhythmias. Rhabdomyolysis and acute renal failure can develop. Malignant hyperthermia should be suspected in patients with a family history of problems during anesthesia.

Malignant hyperthermia is life-threatening unless treated promptly and aggressively. Supportive measures include hydration and decreasing the fever. Dantrolene, a skeletal muscle relaxant, is given as a bolus of 1 mg/kg intravenously and then 2 mg/kg every 5 to 10 minutes until the symptoms resolve. Response to dantrolene is not diagnostic of the disorder but is supportive if signs and symptoms resolve quickly. For those patients with a known history, pretreatment with dantrolene before the anesthetic agent is administered prevents the development of symptoms.
* Cryptogenic organizing pneumonia most often presents with subacute disease progression and bilateral opacities on chest radiograph.

This nonsmoker without any exposure history has acute to subacute development of nonspecific systemic and respiratory symptoms with a dominant alveolar (opacification) process on chest radiograph. The tempo of the disease process is the key to differentiating cryptogenic organizing pneumonia (COP) from other interstitial lung diseases. COP (formerly called idiopathic bronchiolitis obliterans organizing pneumonia) is often acute or subacute, with symptom onset occurring within 2 months of presentation in three fourths of patients. The presentation is so suggestive of an acute or subacute lower respiratory tract infection that patients have almost always been treated with and failed to respond to one or more courses of antibiotics before diagnosis.

Idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia (NSIP), or lymphocytic interstitial pneumonia (LIP) typically follows a prolonged course with evidence of respiratory symptoms and radiographic findings that progress slowly over months or years. Radiographic findings in COP are also distinct from those in IPF, NSIP, and LIP. A dominant alveolar opacification process is typically present in patients with COP. The opacities are almost always bilateral with varied distribution. One of the key radiographic features of COP is the tendency for COP opacities to "migrate" or involve different areas of the lung on serial examinations. Although the radiographic findings of IPF, NSIP, and LIP are varied, they all have a dominant interstitial (reticular) pattern with or without opacities. LIP (which is very rare) is one of the few interstitial lung diseases that can present with cystic changes on high-resolution CT.
* A pulmonary presentation including pneumothorax and abnormal chest imaging often showing cysts/nodules is the primary event leading to the diagnosis of lymphangioleiomyomatosis in most patients.

This patient presents with subacute respiratory complaints and high-resolution CT findings of diffuse cysts in the clinical context of a young woman with a spontaneous pneumothorax who is otherwise healthy and has never smoked. The diagnosis is most likely lymphangioleiomyomatosis (LAM), a rare disease that accounts for less than 1% of all cases of interstitial lung diseases and occurs nearly exclusively in women in their childbearing years. The histopathologic feature of pulmonary LAM is proliferation of atypical smooth muscle-like cells associated with cystic changes. LAM may occur in patients with multiorgan hamartomas and a diagnosis of the autosomal dominant neurocutaneous syndrome called tuberous sclerosis complex. LAM also may present as a sporadic form in which renal and lymphatic hamartomas occur without diagnostic criteria for the tuberous sclerosis complex. The sporadic form of LAM presents with pulmonary complications and occurs only in women. Spontaneous pneumothorax is the initial cause for presentation in 36% of cases. Physical examination is often normal. Crackles and digital clubbing are usually absent.

Many young women with LAM are initially thought to have emphysema. However, patients with LAM are much younger than those with emphysema and present with respiratory complications 86% of the time, which include pneumothorax, as in this case, and chylothorax. Although the HRCT appearance of emphysema may mimic LAM, the cystic air spaces that occur in LAM are more uniform in appearance and distribution. Testing for α1-antitrypsin deficiency may be appropriate to exclude emphysema in young, nonsmoking patients.
* Immediate pleural space drainage, with or without fibrinolytic therapy, is indicated in a patient with acute bacterial pneumonia and a parapneumonic effusion with septations.

Pleural infections often resolve with antibiotic therapy alone, but fibrinous organization and lung entrapment require invasive treatment in about 10% of parapneumonic effusions. Effusions at risk for loculation are called complicated parapneumonic effusions. Because clinical prediction is unreliable, thoracentesis should be done to assess the need for invasive treatment provided that the effusion can be clearly visualized on ultrasonography. This patient with presumed underlying chronic obstructive pulmonary disease had typical symptoms of an acute bacterial pneumonia with development of a parapneumonic effusion with septations, low pleural fluid pH, low glucose, and elevated lactate dehydrogenase level. All of these factors suggest that the patient will have a poor outcome without immediate pleural space drainage with either thoracostomy tube placement or a radiologically guided small-bore catheter. The evidence for use of fibrinolytic agents is still unclear, but in this situation, pleural space drainage is imperative and, with the ultrasonographic findings, a trial of a fibrinolytic agent is warranted before performing video-assisted thoracoscopic surgery (VATS). Intrapleural administration of fibrinolytic agents does not cause systemic thrombolysis. Early VATS or thoracotomy is the generally preferred approach for patients who are candidates for surgery and who have persistent sepsis and loculation.
* The characteristic features of allergic bronchopulmonary aspergillosis include moderate to severe persistent asthma, bronchiectasis and chest radiographic abnormalities, elevated serum IgE level, eosinophilia, and a positive skin test to Aspergillus fumigatus.

Allergic bronchopulmonary aspergillosis (ABPA) is a rare (occurring in 1% to 2% of patients with asthma), but important, complication in patients with asthma. These patients develop humoral and cell-mediated immune responses to Aspergillus fumigatus in their airways, leading to persistent inflammation, airway damage with development of central bronchiectasis, and eventually pulmonary fibrosis. Features of the disorder include moderate to severe persistent asthma, expectoration of brown sputum that contains Aspergillus organisms, bronchiectasis and radiologic abnormalities (infiltrate, mucous plugging), elevated levels of serum total IgE (typically greater than 0.1 mg/dL [1.0 mg/L]), a positive skin test to A. fumigatus, and eosinophilia. Treatment often requires the use of systemic corticosteroids. A skin test to determine the presence of allergic response to Aspergillus is an important first step in evaluating patients with ABPA because essentially all patients with ABPA have a positive skin test. However, many patients with a positive skin test do not have ABPA, and therefore, the positive predictive value of the skin test is low. A negative skin prick test followed by negative intradermal skin test virtually excludes the diagnosis of ABPA, provided that the tests were done using optimal extracts and technique. If the skin test is positive, the next diagnostic step is measurement of serum total IgE. ABPA is excluded if the serum total IgE concentration is less than 0.1 mg/dL (1.0 mg/L). If skin testing for Aspergillus is not available, measuring serum total IgE may be an efficient way to pursue the diagnosis.
* A high-dose nicotine patch in combination with another antismoking therapy, such as nicotine replacement therapy (gum and/or spray), is the most effective therapy for smoking cessation.

This patient has already used a nicotine patch unsuccessfully. However, using the high-dose patch again but in combination with another therapy, such as nicotine replacement with gum or spray, gives the best long-term cessation rate.

Bupropion has been shown to be effective in smoking cessation and is generally well tolerated. However, seizures occur in approximately 0.1% of patients who take the drug, and the risk appears to be higher in patients with a preexisting seizure disorder, anorexia nervosa, or bulimia. This patient has a history of seizure disorder, and, therefore, bupropion is contraindicated.

Varenicline can be used for smoking cessation, and the patient should try to stop smoking 1 week after starting varenicline. The common side effects are nausea and abnormal dreams. The U.S. Food and Drug Administration (FDA) has issued information regarding post-marketing reports of suicidal thoughts and erratic/aggressive behavior in patients who have taken varenicline. Many cases suggest new-onset depression, suicidal ideation, and emotional/behavioral changes within days to weeks after treatment initiation. It is not clear whether these effects are related to the drug itself or to the effects of smoking cessation. In this patient with a history of major depression and suicidal ideation, varenicline would not be indicated. In 2008, the FDA reported that it is increasingly likely that varenicline is associated with serious neuropsychiatric symptoms. There are also reports of patients experiencing drowsiness that affects their ability to drive or operate heavy machinery.
* Pralidoxime (2-PAM) reactivates acetylcholinesterase and can reverse the muscle weakness, paralysis, and respiratory depression of organophosphate toxicity.

This patient likely has organophosphate poisoning. Organophosphates are a diverse group of chemicals used in both domestic and industrial settings that include insecticides, nerve gases (soman, sarin, tabun, VX), ophthalmic agents (echothiophate, isoflurophate), and antihelmintics (trichlorfon). Exposure to organophosphate insecticides may occur by dermal, gastrointestinal, inhalational, and intravenous routes. Organophosphate insecticides inhibit both cholinesterase and pseudocholinesterase activities. The inhibition of cholinesterase activity leads to accumulation of acetylcholine at synapses, causing overstimulation and disruption of neurotransmission in both the central and peripheral nervous systems. Signs and symptoms of organophosphate poisoning include muscarinic effects, nicotinic effects, and central nervous system effects peripherally at muscarinic receptors and nicotinic receptors. Muscarinic manifestations include excessive salivation, diarrhea, vomiting, hypersalivation, respiratory distress with bronchorrhea and bronchospasm, abdominal pain, depressed level of consciousness, and muscle fasciculations. The muscarinic signs of organophosphate poisoning can be recalled with the help of the mnemonic DUMBELS—Defecation, Urination, Miosis, Bronchorrhea/Bronchospasm/Bradycardia, Emesis, Lacrimation, Salivation. Nicotinic manifestations include increased muscle weakness, skeletal muscle fasciculations, and respiratory failure secondary to diaphragmatic paralysis. Central nervous system effects include altered mental status and seizures. Organophosphate insecticide poisoning is a serious condition that requires rapid diagnosis and treatment.