Chest radiography: a tool for the audit of report quality.

In a radiology department, clinical audit implies multiple readings of selected images to identify those findings that should be recognized and to document any departure from this standard for each radiologist. The authors developed an alternate approach for an audit on the basis of clinical outcomes collected in a medical computing facility. Techniques borrowed from information theory were used to measure the clinical information contributed by radiologists as they interpreted chest radiographs. The reported findings were evaluated in light of the discharge diagnosis. The scores generated quantified the information contributed to the final diagnosis by the radiologist's description. This audit approach was tested in a group of 100 chest radiographs. Significant differences were found in the mean scores for information contributed by five different readers. These differences were similar to differences demonstrated in audits by means of multiple readings of chest radiographs. These results support use of a form of audit that is substantially less expensive and time consuming than that typically used in radiology departments.

Large airway size, lung size, and maximal expiratory flow in healthy nonsmokers.

It has been postulated that airway size and lung size may be dissociated because of developmental differences between the tracheobronchial tree and the pulmonary parenchyma (dysanapsis). To test this hypothesis, we compared measurements of airway size (diameters, cross-sectional area, length and volume of the trachea, diameter and cross-sectional area of the mainstem bronchi) and lung size (total lung capacity, thoracic diameters, lung length), as determined from plain chest radiographs in 79 male and 86 female healthy nonsmokers. In both groups of subjects, the correlation between indexes of airway size and lung size was low. Airway size was not significantly different between men and women, when standardized for lung size. Tracheal diameter and length tended to increase with age. To assess the value of airway size measurements in the prediction of maximal expiratory flow, we compared tracheal and bronchial size with FVC, FEV 0.5, FEV1, and mean forced expiratory flow during the middle half of VC. The correlation between airway size and spirometric indexes was very low. Multiple regression analysis showed that the use of airway size variables in addition to the age and height variables did not substantially improve the prediction of maximal expiratory flow. Our results are consistent with the dysanapsis hypothesis, but they suggest that the introduction of radiologic estimates of large airway size in the prediction equations relating maximal expiratory flow to age and height is not justified, at least in the general population.

Gas-blood Pco2 and Po2 equilibration in a steady-state rebreathing dog preparation.

Alveolar gas and mixed venous blood PCO2 and PO2 were compared in a steady-state rebreathing dog preparation, during spontaneous breathing and mechanical ventilation, by a new null-balancing method that removes potential biases in the comparison of measurements in the blood and gas phases and includes an inert gas test to verify the equilibration between the rebreathing lung and the bag. No systematic PCO2 and PO2 differences were observed under equilibrium conditions. However, inert gas studies suggested that a high percentage of measurements obtained during spontaneous breathing were unreliable because of inadequate equilibration between blood and rebreathing bag (attributable to reduced ventilation or perfusion) and that all mechanical ventilation measurements were acceptable. The present data support the view that no PCO2 or PO2 gradients exist when the pulmonary capillary blood and alveolar gas are in equilibrium; the data also suggest that the steady-state rebreathing dog preparation may not be completely stable and that the time course of PCO2 and PO2 in the rebreathing bag may not be reliable as a means of assessing the equilibration between blood and bag.