Routine chest radiographs in exacerbations of chronic obstructive pulmonary disease. Diagnostic value.

Routine admission chest radiographs were abnormal in 35 (14%) of 242 patients hospitalized with an exacerbation of chronic obstructive pulmonary disease and resulted in management changes that were appropriate and clinically significant in only 11 cases (4.5%). Based on our analysis of clinical variables predictive of significant radiographic abnormalities and our assessment of clinically important findings, we propose the following indications for admission chest radiographs in patients with an acute exacerbation of chronic obstructive pulmonary disease: white blood cell count above 15 x 10(9)/L and polymorphonuclear leukocyte count above 8 x 10(9)/L, history of congestive heart failure, history of coronary artery disease, chest pain, or edema. In view of the low yield of clinically significant abnormalities, we believe that routine chest radiographs need not be performed in this patient population. The use of selective criteria could eliminate unnecessary studies while assuring recognition of important new radiographic abnormalities.

Cardiac compliance and dimensions in carbon monoxide-induced cardiomegaly.

Adult male rats inhaled 500 ppm CO continuously for 38 to 47 days to produce significant cardiomegaly. In a first experiment in which heart wall stiffness was examined, haematocrit rose 45.1% and the ratio of the sum of right ventricle (RV) and left ventricle (LV) to body weight (mg X g-1) increased from 2.69 to 3.34. Compliance (ml X mmHg-1) of CO LV's and RV's studied from 0 to 25 mmHg intraluminal pressure, was generally greater than that of LV's and RV's from controls at the same pressure. These differences were greater for RV's. There was no difference between control RV's and LV's at the same distending pressure. The differences between treated and control groups disappeared when compliance was normalised per g heart weight. In a second experiment in which heart dimensions were examined, haematocrit ratio increased 48.6% and 2V (RV + LV) to body weight ratio (mg X g-1) increased from 2.77 to 3.45. Atrial weight was also greater. LV apex to base length increased 6.4% and LV outside diameter increased 7.3. No significant differences in LV, RV or interventricular septum (S) thickness resulted from CO exposure, as measured at three sites in each, in four cross-sections of the heart between the apex and base. In general, LV wall was slightly thicker than S, while RV was about 35% that of LV. The findings suggest that chronic carboxyhaemoglobinaemia produces largely eccentric cardiomegaly, and that there is no intrinsic change in wall stiffness.