[Cardiothoracic ratio and roentgenologic heart size as the indices of body fluid retention in uremics under hemodialysis].

We evaluated the cardiothoracic ratio (CTR) and the roentgenologic heart size (RHS) as the indices of body fluid retention in 31 of uremic patients under hemodialysis. The maximum changes of the roentgenologic thoracic diameter, measured monthly for one year in 31 patients, varied from 10 to 68 mm. The average differences of RHS and CTR between maximum inspiration and forced inspiration in 18 healthy people were 1 mm (RHS) and 2.5% (CTR), respectively, and the change of roentgenologic thoracic diameter was 12 mm. The error of repeated CTR measurements in a period of one year could be estimated more than 2%. In 22 patients the body weight reduction of 1 kg corresponded to a 4 mm decrease of RHS (p less than 0.005) and 1.5% of CTR (p less than 0.05), respectively. In relation to the change of body fluid balance assessed by the change of body weight, RHS showed a higher correlation than CTR. These results could be attributed that RHS was hardly influenced by the respiration, whereas CTR was surprisingly affected. It is concluded that the measurement of RHS is more useful as an index of control of body fluid balance than CTR.