TABLE IV-114 Risk Factors for Active Tuberculosis Among Persons Who Have Been Infected With Tubercle Bacilli 15 page

Organic dusts that can lead to occupational lung disease include cotton dust, grain dust, toxic chemicals, and other agricultural dusts, among many others. Cotton milling and processing can present with a clinical syndrome known as byssinosis, which has asthma-like features. Many of the organic dust exposures also lead to hypersensitivity pneumonitis. Examples of hypersensitivity pneumonitis syndromes related to occupational exposures include farmer’s lung, pigeon breeder’s lung, and malt worker’s lung. Typically, a specific antigen can be identified as the culprit for the development of hypersensitivity pneumonitis. In farmer’s lung, the most common cause is thermophilic Actinomyces

species found in moldy hay.

VI-21. The answer is B. (Chaps. 254 and 256) The patient presents with typical asthma symptoms; however, the symptoms are escalating and now require nearly constant use of oral steroids. It is of note that the symptoms are worse during weekdays and better on weekends. This finding suggests that there is an exposure during the week that may be triggering the patient’s asthma. Often textile workers have asthma resulting from the inhalation of particles. The first step in diagnosing a work-related asthma trigger is to check FEV₁ before and after the first shift of the workweek. A decrease in FEV₁ would suggest an occupational exposure. Skin testing for allergies would not be likely to pinpoint the work-related exposure. Although A. fumigatus can be associated with worsening asthma from allergic bronchopulmonary aspergillosis, this would not result in a fluctuation in symptoms throughout the week. The patient does not require further testing to diagnose that he has asthma; therefore, a methacholine challenge is not indicated. Finally, the exercise physiology test is generally used to differentiate between cardiac and pulmonary causes or deconditioning as etiologies for shortness of breath.

VI-22. The answer is D. (Chap. 256) The patient presents with acute-onset pulmonary symptoms, including wheezing, with no other medical problems. He is a farmer and was recently handling hay. The clinical presentation and radiogram are consistent with farmer’s lung, a hypersensitivity pneumonitis caused by Actinomyces. In this disorder, spores of actinomycetes in moldy hay are inhaled and produce a hypersensitivity pneumonitis. The disorder is seen most commonly in rainy periods, when the spores multiply. Patients present generally 4–8 hours after exposure with fever, cough, and shortness of breath without wheezing. Chest radiograms often show patchy, bilateral, often upper-lobe infiltrates. The exposure history will differentiate this disorder from other types of pneumonia.

VI-23. The answer is A. (Chap. 257) Health care–associated pneumonia (HCAP) has emerged as a new category of pneumonia distinct from community-acquired pneumonia (CAP), as individuals at risk of HCAP frequently have multidrug-resistant organisms more typical of hospital-acquired pneumonia (HAP). Several risk factors have been identified for HCAP, and specific organisms are more commonly seen in specific situations. For example, methicillin-resistant Staphylococcus aureus (MRSA) has not only been associated with hospitalization for more than 48 hours, but also any hospitalization for 2 or more days in the preceding 3 months, as well as with individuals residing in nursing homes or extended care facilities, chronic dialysis, home infusion therapy, home wound care, or a family member with a multidrug-resistant infection. Antibiotic therapy in the preceding 3 months is not associated with the development of MRSA as a cause of HCAP, but is associated with Pseudomonas aeruginosa and multidrug-resistant (MDR) Enterobacteriaceae as causes of HCAP.

VI-24. The answer is B. (Chap. 257) The diagnosis and treatment of community-acquired pneumonia (CAP) often incorporate a combination of clinical, radiographic, and laboratory features to determine the most likely etiology and treatment. In most instances of CAP, outpatient treatment is sufficient, and definitive etiologic diagnosis of the causative organism is not required, nor is it cost-effective. However, the outpatient diagnosis of CAP most often does require confirmation by chest radiograph, as the sensitivity and specificity of the findings on physical examination are about 58% and 67%, respectively. In addition, chest radiograph may identify risk factors for more severe clinical courses such as multifocal infiltrates. Moreover, outside of the 2% of individuals admitted to intensive care for treatment of CAP, there are no data that treatment directed against the specific causative organism is

superior to empiric therapy. In some instances, one may decide to attempt to determine a causative organism for CAP, particularly in individuals who have risk factors for resistant organisms or if the patient fails to respond appropriately to initial antibiotic therapy. The most common way CAP is diagnosed is via sputum culture with Gram stain. The primary purpose of the Gram stain is to ensure that the sputum is an adequate lower respiratory sample for culture with fewer than 10 squamous epithelial cells and more than 25 neutrophils per high-powered field. However, at times it can suggest a specific diagnosis based on the appearance. Generally, the yield from sputum culture is 50% or less, even in cases of bacteremic pneumococcal pneumonia. The yield from blood cultures is also low, even when collected prior to initiation of antibiotics, at 5–14%. More recently, antigen tests or polymerase chain reaction (PCR) testing directed against specific organisms has gained favor. The most common antigen test that is performed is for Legionella pneumophila, as this organism does not grow in culture unless performed on specific media. Antigen and PCR tests are also available for Streptococcus pneumoniae and Mycoplasma pneumoniae, but given the costs they are not frequently performed

VI-25. The answer is D. (Chap. 257) Determining the appropriate empiric coverage for community-acquired pneumonia (CAP) initially requires determining if the severity of illness warrants admission to the hospital. Clinical rules for determining the potential severity of pneumonia have been developed including the Pneumonia Severity Index (PSI) and the CURB-65 criteria. While the PSI has the largest body of research to support its use, the model includes 20 variables, which may be impractical in a busy clinical practice. The CURB-65 criteria include only five variables: (1) Confusion; (2) Urea greater than 7 mmol/L; (3) Respiratory rate greater than or equal to 30/min; (4) Blood pressure less than or equal to 90/60; and (5) age of 65 or older. This patient meets none of the criteria for hospitalization and is not hypoxemic or in a high-risk group for complications from CAP. Therefore, he can safely be treated as an outpatient without further diagnostic workup, as his history, physical examination, and chest radiograph are all consistent with the diagnosis of CAP. The empiric antibiotic regimen recommended by the Infectious Diseases Society of America and the American Thoracic Society for individuals who are previously healthy and have not received antibiotics in the prior 3 months is either doxycycline or a macrolide such as azithromycin or clarithromycin. In outpatients with significant medical comorbidities or antibiotics within the prior 3 months, the suggested antibiotic therapy is either a respiratory fluoroquinolone or a beta-lactam plus a macrolide.

VI-26. The answer is E. (Chap. 257) Ventilator-associated pneumonia (VAP) is a common complication of endotracheal intubation and mechanical ventilation. Prevalence estimates indicate that 70% of patients requiring mechanical ventilation for 30 days or longer will have at least one instance of VAP. However, the epidemiology of VA P has been difficult to accurately study as no single set of criteria is reliably diagnostic of VAP. Generally, it is thought that VA P has a tendency to be overdiagnosed for a variety of reasons, including the high rates of tracheal colonization with pathogenic organisms and the multiple alternative causes of fevers and/or pulmonary infiltrates in critically ill patients. Quantitative cultures have gained favor, as the quantitative nature is thought to discriminate better between colonization and active infection. A variety of approaches have been advocated including endotracheal aspirates yielding more than 10⁶ organisms or protected brush specimens from distal airways yielding more than 10³ organisms. However, the quantitative yield of these tests can be highly influenced by even a single dose of antibiotics, and antibiotic changes are common in critically ill patients, particularly when a new fever has emerged. Thus, the lack of growth on quantitative culture may be difficult to interpret in this setting. More recently, there has been growing use of the Clinical Pulmonary

Infection Score (CPIS), which incorporates a variety of clinical, radiographic, and laboratory factors to determine the likelihood of VAP, although its true utility in clinical practice remains to be fully determined.

VI-27. The answer is D. (Chap. 257) Aspiration can lead to anaerobic infection and chemical pneumonitis. The etiologic differential diagnosis of community-acquired pneumonia (CAP) in a patient with a history of recent travel to the southwestern United States should include Coccidioides. Aspergillus has a worldwide distribution and is not a cause of CAP syndrome. Alcohol use predisposes patients to anaerobic infection, likely due to aspiration, as well as S. pneumoniae. Klebsiella is classically associated with CAP in alcoholic patients, but in reality this is rarely seen. Patients with structural lung disease, such as cystic fibrosis or bronchiectasis, are at risk for a unique group of organisms including P. aeruginosa and S. aureus. Poor dental hygiene is associated with anaerobic infections.

VI-28. The answer is D. (Chap. 258) Bronchiectasis occurs when there is irreversible dilation of the distal airways and can occur in a focal or diffuse fashion. The most common cause of diffuse bronchiectasis worldwide is prior granulomatous infection due to Mycobacterium tuberculosis. In the developed world, tuberculosis is a less common cause of bronchiectasis, with nontuberculous mycobacteria such as Mycobacterium avium-intracellulare complex being a more common cause, particularly in the midlung fields. Other potential etiologies of diffuse bronchiectasis include cystic fibrosis, postradiation pneumonitis, immunoglobulin deficiency, end-stage fibrotic lung disease, and recurrent aspiration. However, despite extensive workup, as many as 25–50% of cases remain idiopathic.

VI-29. The answer is C. (Chap. 258) Bronchiectasis is a disorder with a variable presentation depending on cause. In inherited disorders such as cystic fibrosis, the symptoms of bronchiectasis most often begin in early childhood. However, in general, the incidence of bronchiectasis increases with age, typically affecting women more than men. The primary clinical symptom of bronchiectasis is a daily productive cough. Classically, the sputum is described as large volume with a thick tenacious character. Hemoptysis may also occur in association with bronchiectasis. The physical examination may demonstrate crackles or wheezing with mild to moderate airflow obstruction on pulmonary function testing. In more advanced cases, digital clubbing may be seen. The diagnosis of bronchiectasis is often suspected based on clinical symptoms, but confirmation of diagnosis on high-resolution CT imaging of the chest is recommended. The chest radiograph may show tram tracking, but is frequently normal and is of insufficient sensitivity to definitively make the diagnosis. On high-resolution chest CT imaging, bronchiectatic airways appear dilated more than 1.5 times the size of the adjacent pulmonary artery. In addition, the airways fail to taper in the periphery, and airways may be identifiable within 1 cm of the pleural surface, which is clearly abnormal. Bronchial wall thickening and inspissated secretions may also be seen. Contrast administration is not necessary to visualize bronchiectasis. Once bronchiectasis is confirmed as the etiology of the patient’s chronic cough, workup for the underlying etiology of the bronchiectasis should be performed and would likely include sputum cultures for mycobacteria and bacteria, serum immunoglobulin, and α₁ antitrypsin levels, among others.

VI-30. The answer is A. (Chap. 258) This patient presents with a clinical history that is consistent with a polymicrobial lung abscess with infection by anaerobic bacteria. Often individuals present with an

indolent course and nonspecific symptoms including fever, fatigue, and weight loss. Cough with a foul-smelling sputum production may also be seen. Individuals presenting with lung abscess often have risk factors for aspiration and evidence of periodontal infection. In more advanced cases, the lung abscess can erode into the pleura, creating an empyema with associated pleuritic chest pain. Although chest radiograph often demonstrates a cavitary lesion, a CT may be performed to determine the extent of the disease and whether there are associated lesions. Bacterial, mycobacterial, and fungal cultures should be performed, but this should not delay treatment of the most likely cause of the lung abscess. A sputum culture on an expectorated sample will only detect aerobic organisms, and the detection of anaerobes would be confounded by the presence of multiple oral anaerobes that could contaminate an expectorated specimen. Initial treatment should be directed primarily at anaerobic organisms. Recommended antibiotics are clindamycin IV 600 mg four times daily or a β-lactam/β-lactamase inhibitor combination (ampicillin-sulbactam, amoxicillin-clavulanic acid). Metronidazole is not recommended because it has poor activity against the microaerophilic streptococci that commonly infect lung abscesses. The duration of treatment is not well defined. Some experts recommend continuing therapy until the abscess has entirely healed. Persistence of fever beyond 5–7 days should prompt the clinician to investigate further. Potential complications include development of empyema or a bronchopleural fistula. In addition, one should consider performing bronchoscopy to rule out an obstructing lesion. Percutaneous or surgical intervention is generally not required unless the patient fails to respond to antibiotic therapy or has a lung abscess greater than 6 cm.

VI-31. The answer is D. (Chap. 258) The combination of infertility and recurrent sinopulmonary infections should prompt consideration of an underlying disorder of ciliary dysfunction that is termed primary ciliary dyskinesia. These disorders account for approximately 5–10% of cases of bronchiectasis. A number of deficiencies have been described, including malfunction of dynein arms, radial spokes, and microtubules. All organ systems that require ciliary function are affected. The lungs rely on cilia to beat respiratory secretions proximally and subsequently to remove inspired particles, especially bacteria. In the absence of this normal host defense, recurrent bacterial respiratory infections occur and can lead to bronchiectasis. Otitis media and sinusitis are common for the same reason. In the genitourinary tract, sperm require cilia to provide motility. Kartagener’s syndrome is a combination of sinusitis, bronchiectasis, and situs inversus. It accounts for approximately 50% of patients with primary ciliary dyskinesia. Cystic fibrosis is associated with infertility and bilateral upper-lobe infiltrates. It causes a decreased number of sperm or absent sperm on analysis because of the congenital absence of the vas deferens. Sarcoidosis, which is often associated with bihilar adenopathy, is not generally a cause of infertility. A water balloon–shaped heart is found in those with pericardial effusions, which one would not expect in this patient.

VI-32. The answer is E. (Chap. 259) Cystic fibrosis (CF) is a common autosomal-recessive disorder that affects 1 out of every 3000 live births in the Caucasian population of North America and Europe. There have been more than 1500 mutations identified in the gene for the cystic fibrosis transmembrane conductance regulator (CFTR)—the abnormal protein identified in CF. This protein is a large transmembrane protein involved in the transport of chloride and other ions, and abnormalities of the CFTR lead to abnormalities of salt and water transport. The primary clinical manifestations of CF are due to the effects of the mutated CFTR in the lungs, gastrointestinal tract, and pancreas. In the lungs, abnormal CFTR leads to thick, sticky mucus with abnormal mucociliary clearance. A patient will have recurrent respiratory infections with development of cystic bronchiectasis over time. The presenting

manifestation in infancy is often meconium ileus and can lead to constipation and distal intestinal obstruction in adults. Failure of the CFTR in the pancreas prevents appropriate release of pancreatic enzymes to allow for proper digestion of food, especially fatty foods, with resultant malnutrition and steatorrhea. While most patients with CF present in infancy or childhood, about 5% of all individuals with CF will not be diagnosed until adulthood. Presenting symptoms in adulthood can be myriad and often result from minor mutations of the CFTR gene. These symptoms can include recurrent lung and sinus infections, malnutrition, sinus disease, and infertility, especially absence of the vas deferens in men. The standard test for the diagnosis of CF is the sweat chloride test. Elevated values are pathognomonic for CF, with a cutoff of greater than 70 meq/L in adults being diagnostic. Values greater than approximately 35 meq/L fall within the indeterminate range. DNA analysis for common CF mutations is often performed, and one would want to demonstrate two alleles known to cause CF before making the diagnosis, as the disease is autosomal recessive. Identification of only one allele only identifies the carrier state. In some individuals, the diagnosis can remain elusive. In such cases, referral to a tertiary center for nasal potential difference (PD) testing can be helpful, as CF patients demonstrate an elevated baseline nasal PD with failure to respond to stimulation with beta-agonists. Presence of Pseudomonas aeruginosa is common in adults with CF, but is not specific for the diagnosis of the disease as bronchiectasis from any cause can lead to P. aeruginosa colonization.

VI-33. The answer is C. (Chap. 259) Individuals with cystic fibrosis (CF) experience recurrent pulmonary and sinus infections. In childhood, the most commonly isolated organisms are Haemophilus influenzae and Staphylococcus aureus. However, over time, most adults demonstrate Pseudomonas aeruginosa. It is now recognized that chronic colonization with Pseudomonas, especially multidrug-resistant organisms, is associated with a more rapid decline in lung function. The Cystic Fibrosis Foundation recommends quarterly office visits with a physician, with assessment of respiratory cultures at each visit. When Pseudomonas is initially detected, attempts to eradicate the organism should be undertaken. Clinical trials have not definitively determined the best regimen for eradicating Pseudomonas, but the most common utilized treatment is the aminoglycoside antibiotic tobramycin given as a nebulized solution twice daily every other month with follow-up cultures at the next office visit to determine if the therapy should be continued. For all patients chronically colonized with Pseudomonas, inhaled tobramycin every other month should be continued on an indefinite basis. In addition, azithromycin 500 mg three times weekly or 250 mg daily is also utilized. Whether azithromycin primarily exerts its beneficial effect through anti-inflammatory or antimicrobial actions is not definitively known at the present time. As the patient is clinically well without any symptoms of acute exacerbation, the use of intravenous antibiotics is not required. Chest wall oscillation and hypertonic saline are both mechanisms to improve airway clearance. By history and lung function, the patient is achieving adequate airway clearance at the present time, so escalation of care in this area is not required.

VI-34. The answer is B. (Chap. 259) Patients with cystic fibrosis are at risk for colonization and/or infection with a number of pathogens, and in general these infections have a temporal relationship. In childhood, the most frequently isolated organisms are Haemophilus influenzae and Staphylococcus aureus. As patients age, Pseudomonas aeruginosa becomes the predominant pathogen. Interestingly, Aspergillus fumigatus is found in the airways of up to 50% of cystic fibrosis patients. All these organisms merely colonize the airways but occasionally can also cause disease. Burkholderia (previously called Pseudomonas) cepacia can occasionally be found in the sputum of cystic fibrosis

patients, where it is always pathogenic and is associated with a rapid decline in both clinical parameters and pulmonary function testing. Atypical mycobacteria can occasionally be found in the sputum but are often merely colonizers. Acinetobacter baumannii is not associated with cystic fibrosis; rather, it is generally found in nosocomial infections.

VI-35. The answer is D. (Chap. 260) Chronic obstructive pulmonary disease (COPD) affects more than 10 million Americans and is currently the fourth leading cause of death in the United States. Worldwide, COPD is also increasing as cigarette smoking, the primary risk factor for the development of COPD, is increasing in prevalence throughout the world. While cigarette smoking is clearly identified as a risk factor for COPD, other factors have also been identified to contribute to the risk of COPD. In many developing countries, the prevalence of smoking among women remains low. However, the incidence of COPD is increasing in women as well as men. In many developing countries, this increased incidence of COPD in women is attributable to the use of biomass fuels in poorly ventilated areas for heat and cooking. In addition, passive cigarette smoke exposure may also contribute. Occupational exposures also lead to an increased risk of COPD. While some exposures such as cotton textile dust and gold mining have not been definitively associated with COPD, coal dust exposure is a risk factor for emphysema in both smokers and nonsmokers. Inherent properties of the airways also affect the risk of COPD. Airway hyperresponsiveness increases the risk of lung function decline and is a risk factor for COPD. While there is much interest in the role of chronic or recurrent infections as a risk factor for COPD, there has been no proven link.

VI-36. The answer is B. (Chap. 260) Chronic obstructive pulmonary disease (COPD) is a disease process encompassing the clinical entities of emphysema and chronic bronchitis. COPD is defined pathophysiologically by the presence of irreversible airflow obstruction with hyperinflation and impaired gas exchange. The airflow obstruction occurs for several reasons including decreased elastic recoil of the lungs, increased airway inflammation, and increased closure of small airways due to loss of tethering in emphysematous lungs. This leads to early closure of airways in expiration with air trapping and hyperinflation. Finally, the loss of alveoli in emphysematous lungs leads to a progressive decline in gas exchange with alterations of ventilation-perfusion relationships. On pulmonary function testing, these pathophysiologic changes result in a typical pattern, with the primary characteristic of COPD being a decrease in the FEV₁/FVC ratio and FEV₁. The severity of airflow obstruction is graded by the degree of decline in the percentage predicted FEV₁. The FVC may or may not be decreased. With

hyperinflation, the total lung capacity increases with a concomitant increase in residual volume. Finally, the diffusion capacity for carbon monoxide is also characteristically decreased in most cases of COPD. Some patients with pure chronic bronchitis without any emphysematous component may have a preserved carbon monoxide diffusing capacity (DLCO). This same pattern of pulmonary function testing can be seen in asthma with the exception of the DLCO, which is normal or increased in asthma.

VI-37. The answer is D. (Chap. 260) This patient has a known diagnosis of chronic obstructive pulmonary disease (COPD) with worsening symptoms and pulmonary function testing consistent with a moderate degree of disease. By the Global Initiative for Lung Disease (GOLD) criteria, the patient would have stage II disease. He is currently undermanaged with a short-acting beta-agonist only in the setting of limiting symptoms. Unfortunately, there is no medical therapy that alters mortality or definitively decreases the rate of decline in lung function in COPD, with the exception of smoking cessation, oxygen for chronic hypoxemia, and lung volume reduction surgery in a small subset of highly

selected patients. Therefore, the goal of therapy in COPD is to improve symptoms and quality of life. The best initial medication for this patient would be to add a long-acting bronchodilator in the form of the antimuscarinic agent tiotropium. In large randomized controlled trials, tiotropium has been demonstrated to improve symptoms and decrease exacerbations in COPD. Ipratropium, a short-acting anticholinergic medication, also improves symptoms, but has not been similarly shown to decrease exacerbation rate. Combinations of long-acting beta-agonists and inhaled glucocorticoids have also been shown to decrease exacerbations and improve quality of life in those with COPD. The largest trial of these medications to date has demonstrated a trend toward improved mortality. Currently the recommendation for initiation of long-acting beta-agonist and inhaled glucocorticoid combinations is to consider starting the medication if the patient has two or more exacerbations yearly or demonstrates significant acute bronchodilator reactivity on pulmonary function testing. At one time, physicians considered prescribing long-term oral glucocorticoids if a patient demonstrated significant improvement in lung function in response to a trial of oral steroids. However, long-term treatment with steroids has an unfavorable risk-benefit ratio including weight gain, osteoporosis, and increased risk of infection, especially pneumonia. Oxygen therapy improves outcomes in individuals who are hypoxemic at rest or have borderline hypoxemia with evidence of end-organ damage (pulmonary hypertension, polycythemia, etc.). While oxygen may be prescribed for individuals with isolated exercise or nocturnal hypoxemia, research to date has not demonstrated any change in outcomes with oxygen in these settings.

VI-38. The answer is E. (Chap. 260) Acute exacerbations of chronic obstructive pulmonary disease (COPD) are marked by an increase in dyspnea, an increase in sputum, and a change in sputum color. Acute exacerbations of COPD account for more than $10 billion in health care expenditures annually in the United States, with a significant morbidity and mortality associated with these exacerbations. Prompt treatment can improve symptoms and decrease hospitalizations and mortality in this setting. In patients presenting with hypercarbic respiratory failure in the setting of an acute exacerbation, the treatment that has demonstrated the strongest reduction in mortality is noninvasive positive pressure ventilation (NIPPV) when compared to traditional mechanical ventilation. NIPPV also decreases the need for endotracheal intubation, complications, and length of stay in the hospital. Antibiotics, bronchodilators, and glucocorticoids are all cornerstones of therapy in the treatment of acute exacerbations in COPD, but have not been demonstrated in clinical trials to have similar mortality benefits in the situation of acute hypercarbic respiratory failure. Specifically, no benefit is demonstrated for intravenous versus oral corticosteroids. Likewise, the choice of antibiotic should be made based on local susceptibility patterns, and the need for broad-spectrum antibiotics that cover Pseudomonas is not typically indicated.

VI-39. The answer is C. (Chap. 260) The only therapies that have been proven to improve survival in patients with COPD are smoking cessation, oxygen in patients with resting hypoxemia, and lung volume reduction surgery in a very small subset of highly selected patients. This patient probably has resting hypoxemia resulting from the presence of an elevated jugular venous pulse, pedal edema, and an elevated hematocrit. Theophylline has been shown to increase exercise tolerance in patients with COPD through a mechanism other than bronchodilation. Oral glucocorticoids are not indicated in the absence of an acute exacerbation and may lead to complications if they are used indiscriminately. Atenolol and enalapril have no specific role in therapy for COPD but are often used when there is concomitant hypertension or cardiovascular disease.

VI-40. The answer is E. (Chap. 261) Usual interstitial pneumonia is the pathologic hallmark of idiopathic pulmonary fibrosis (IPF), but can occur in rheumatologic disorders or secondary to exposures. If no other cause is identified on history or serologic workup, then the patient is given the diagnosis of IPF. IPF is a disease that typically presents with progressive dyspnea on exertion and dry cough in an older individual. It is rare in individuals younger than 50. On physical examination, inspiratory crackles and clubbing are common. Pulmonary function tests demonstrate restrictive ventilatory defect with a low DLCO. High-resolution chest CT shows interstitial fibrosis that is worse in the bases and begins in the subpleural areas. Bronchoscopy is insufficient for histologic confirmation, and a surgical lung biopsy is required for definitive diagnosis. The natural history of IPF is one of continued progression of disease and a high mortality rate. Acute exacerbations also occur with a rapid progression of symptoms associated with a pattern of diffuse ground-glass opacities on CT. These are associated with a high mortality. Unfortunately, no therapy has been found to be effective for the treatment of IPF. Referral for lung transplantation or participation in clinical trials should be considered in all patients with a diagnosis of IPF.

Date: 2016-04-22; view: 753