Chest
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The positional effect on gas exchange was studied in eight patients who had unilateral pleural fluid without clinical or radiologic evidence of parenchymal lung disease. In all eight patients, PaO2 values were higher when the lung with the pleural fluid was uppermost. The mean PaO2 in this position was 71.9 +/- 9.3 mm Hg (mean +/- SE) compared with 66.7 +/- 8.7 mm Hg in the lateral decubitus position with the pleural fluid lowermost. ⋯ Larger positional differences were found in the patients with the smallest pleural effusions. These results are probably due to perfusion of areas of unventilated lung, accentuated by gravity with a consequent increase in shunting. A large effusion also causes a decrease in perfusion, so that ventilation-perfusion mismatching is decreased and the positional effect on gas exchange diminished.
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Case Reports
Positional dyspnea and oxygen desaturation related to carcinoma of the lung. Up with the good lung.
Body position can lead to respiratory symptoms and affect gas exchange in disease states. We describe a patient with carcinoma of the left lung in whom dyspnea and oxygen desaturation developed in the right lateral position only. Fiberoptic bronchoscopic study demonstrated a tumor mass protruding into the left main-stem bronchus, which caused further narrowing when the patient turned on his right side.
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With improvement in computed tomography (CT) technology, including faster scanning and images with better detail, the indications for CT of the thorax have expanded. In many instances, data collected on earlier-generation scanners no longer apply. This report is an update of CT scanning of the thorax and includes information on the role of CT in diagnosis when specific clinical syndromes and diseases are suspected. It also addresses controversial subjects, such as the role of CT scanning in the staging of bronchogenic carcinoma and the evaluation of the solitary pulmonary nodule, as well as suggesting guidelines for deciding when a CT scan of the thorax is indicated.
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Comparative Study
Clinical studies of measuring extravascular lung water by the thermal dye technique in critically ill patients.
We measured extravascular lung water (EVLW) by the thermal-dye technique in a broad group of critically ill patients who had either acute cardiac or noncardiac illnesses. A portable AP supine chest roentgenogram, reviewed blindly, was used to classify patients as to the presence or absence of pulmonary edema; by clinical history we categorized patients into either a cardiac or noncardiac (ie, ARDS) group. With a normal chest roentgenogram, the mean EVLW was 5.6 +/- 1.8 ml/kg, and the pulmonary capillary wedge pressure (PCWP) was 11.3 +/- 5.3 mm Hg (mean +/- SD). ⋯ On a severity system of 014, the EVLW increased in parallel to the severity of the chest radiologic appearance of edema in both the cardiac (r2 = .44; p less than 0.001) and noncardiac (r2 = .59; p less than 0.001) patients. This study defined a normal range of thermal-dye EVLW in critically ill patients without radiologic evidence of pulmonary edema. We further demonstrated the increased pulmonary microvascular permeability of noncardiac pulmonary edema compared with cardiac edema by the greater EVLW at normal microvascular hydrostatic pressures in the former group.