American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · May 1998
Appraising pulmonary edema using supine chest roentgenograms in ventilated patients.
The role of portable, anteroposterior, supine chest X-rays (CXRs) in distinguishing hydrostatic pulmonary edema (HPE) from permeability pulmonary edema (PPE) in mechanically ventilated patients is controversial. We prospectively obtained and evaluated such CXRs in 33 supine, mechanically ventilated intensive-care-unit patients with pulmonary artery catheters. Three chest radiologists independently reviewed CXRs without clinical information and recorded the cardiothoracic (CT) ratio, vascular pedicle width (VPW), and other radiographic features commonly used to evaluate pulmonary edema. ⋯ With this combination of objective criteria, radiologists' diagnostic accuracy could have been increased to 73%. We therefore conclude that measurements of CT ratio and VPW correlate with pulmonary artery occlusion pressure in supine, mechanically ventilated patients. Distinction of hydrostatic from permeability pulmonary edema is difficult using portable, supine CXRs, but readily assessed radiologic signs may contribute to the correct diagnosis.
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Am. J. Respir. Crit. Care Med. · May 1998
Effect of lung volume reduction surgery on diaphragm strength.
Since lung volume reduction surgery (LVRS) reduces end-expiratory lung volume, we hypothesized that it may improve diaphragm strength. We evaluated 37 patients for pulmonary rehabilitation and LVRS. Before and 8 wk after pulmonary rehabilitation, 24 patients had spirometry, lung volumes, diffusion capacity, incremental symptom limited maximum exercise test, 6-min walk test, maximal static inspiratory and expiratory mouth pressures, and transdiaphragmatic pressures during maximum static inspiratory efforts and bilateral supramaximal electrophrenic twitch stimulation measured. ⋯ On multiple regression analysis, increases in PImax correlated significantly with decreases in RV and FRC(trapped gas) after LVRS (r = 0.67, p < 0.03). We conclude that LVRS significantly improves diaphragm strength that is associated with a reduction in lung volumes and an improvement in exercise performance. Future studies are needed to determine the relationship and stability of these changes over time.