The chest roentgenogram was obtained in the upright position. X-ray tube conditions were set to keep the exposure time to a minimum for each roentgenogram (0.05 s) and were kept constant in successive roentgenograms. Chest x-ray films were read by three observers according to a standardized reading sheet. The following roentgenographic findings, as taken from the literature and our own experience, were considered: (1) the appearance of the right descending pulmonary artery whether normal, enlarged, or with the aspect described as the “sausage sign;” (2) the elevation of the diaphragm, whether absent, monolateral, or bilateral; (3) the presence of Fleischner lines or opacities compatible with pulmonary infarction; and (4) the presence of the Westermark sign of oligoemia whether monolateral or bilateral.
The diameter of the right descending pulmonary artery was measured at the superior venous angle, and the lateral wall of the bronchus intermedius was used as the medial margin of the artery. The diameter was defined as enlarged when it was larger than 16 mm, (that is, the normal upper limit). The “sausage sign” was defined as the descending right pulmonary artery with a cut-off appearance at its lower end, with an increase in width and density, with well-defined borders and no sharp angles, and with the branches, usually not visible in their proximal part, distorted and lumped peripherally. cheap levitra professional
The elevation of the diaphragm was defined by a subjective assessment of the reduced distance between the median portion of the diaphragmatic domes and the lower edge of the fourth dorsal ribs. Fleischner lines were defined as thin and horizontal opacities 2 to 5 mm in thickness and 1 to 4 cm in length, multiple and bilateral, with homogeneous density and undefined borders, that were mainly localized in the lower lungs laterally. The opacities compatible with pulmonary infarction were considered those parenchymal opacities that appeared mainly in the basal zones of the lungs, downstream of an obstructed vascular region, documented by perfusion lung scintigraphy, 2 to 5 cm in diameter, with a coarsely round shape and with a shaded-off contour.
Observed agreement for chest x-ray findings between three readers ranged from 0.48 to 0.74. After correction for chance by computing the kappa value for the considered findings, kappa value ranged from 0.36 to 0.59, thus confirming a good agreement. As a consequence, the frequencies of chest x-ray findings in these 33 patients were obtained on the basis of the absolute agreement of two or three observers.
Statistical analysis was performed using Statistical Package for Social Sciences routines. Linear regression was used to study the relationships between ULSs and gas exchange at each step of data collection. Analysis of variance and the unpaired f-test were used to evaluate the relationships of chest x-ray abnormalities to ULSs and gas exchange and to test the presence of significant variability among the three readers in scoring ULSs at perfusion lung scintigraphy. The kappa value was computed to test the observed agreement for chest x-ray findings among the three readers.
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The Duncan test applied to analysis of variance was used to evaluate the temporal variations of ULSs and gas exchange parameters from diagnosis through 7, 30, and 180 days later.