Journal of thoracic imaging
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Opportunistic fungal infection is a common cause of serious morbidity and mortality in immunocompromised patients. These infections occur primarily in patients with chemotherapy-induced neutropenia, acquired immunodeficiency syndrome. or immunosuppression after solid organ or bone marrow transplantation. The most important opportunistic fungal pathogens include Cryptococcus neoformans, Candida and Aspergillus species, and the fungi that cause mucormycosis. ⋯ Diagnosis requires knowledge of the various modes of presentation, radiologic manifestations, and epidemiology of these infections. Because many of these organisms can colonize the upper airway, sputum cultures are considered diagnostically unreliable. Instead, definitive diagnosis requires culture of the fungus from infected tissue or demonstration of the organism on microscopic examination.
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The endemic fungi Histoplasma capsulatum, Coccidioides immitis, and Blastomyces dermatitidis tend to reside in specific geographic regions. The organisms are pathogenic in that they are able to produce clinical disease in both immunocompromised patients and in patients with normal immunity. These organisms have a variety of clinical presentations, some of which typically are seen in the normal host and others that are primarily encountered in persons with abnormal immunity. Although most of the cases are seen in endemic regions, they may occur in persons who at some time either resided in or traveled to an endemic region.
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The old division of lung edema into two categories--cardiogenic (hydrostatic) and noncardiogenic (increased permeability)--is no longer adequate. For instance, it fails to distinguish between the capillary leak caused by acute respiratory distress syndrome from that caused by interleukin-2 treatment. Further, it fails to account for the capillary leak ('stress-failure') that may accompany edema. ⋯ Thus, a reasonable classification of lung edema requires at least four categories: 1) hydrostatic edema; 2) acute respiratory distress syndrome (permeability edema caused by diffuse alveolar damage); 3) permeability edema without alveolar damage; and (4) mixed hydrostatic and permeability edema. The authors emphasize the importance of the barriers provided by the capillary endothelium and the alveolar epithelium in determining the clinical and radiographic manifestations of edema. In general, when the alveolar epithelium is intact, the radiographic manifestations are those of interstitial (not air-space) edema; this radiographic pattern predicts a mild clinical course and prompt resolution.
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Expandable metallic stents offer advantages over previously available techniques for treating benign tracheobronchial stenosis or obstruction. Endoluminal stent placement offers a rapid and effective means of opening up narrowed airways, and results in excellent relief of symptoms and improvement in pulmonary function. Because they are delivered in a nonexpanded state using flexible over-wire systems, they can be placed using a flexible bronchoscope and can be located in second-order bronchial branches. ⋯ Significant complications can occur, including airway inflammation, stent migration, airway erosion, and stent fracture and collapse, but more serious complications are uncommon. Computed tomography is essential in imaging patients being considered for stent placement, as it allows 1) accurate representation of airway anatomy in three dimensions. 2) measurement of airway diameter, 3) evaluation of airway anatomy distal to a narrowed segment and invisible to bronchoscopy, 4) demonstration of dynamic changes in airway morphologic features during forced exhalation in patients with airway malacia, and 5) demonstration of focal or diffuse air trapping in lung peripheral to the abnormal airway. In patients who have had stent placement, computed tomography is valuable in assessing airway morphologic features and dynamics distal to the stent, and can be valuable in assessing stent dysfunction.
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Pneumothorax is a frequent complication of interventional pulmonary procedures. Percutaneous catheter placement enables safe and effective drainage of pneumothoraces with rapid restoration of vital capacity, oxygenation, and lung reexpansion.