SUBCLINICAL PULMONARY-EDEMA AND INTERMITTENT HEMODIALYSIS

It has been postulated that patients with chronic renal failure, even in the absence of cardiopulmonary symptoms, accumulate interstitial pu lmonary fluid, which is removed by haemodialysis. To test this hypothe sis we used the indocyanine green (ICG)-heavy water double indicator d ilution method to measure lung water, cardiac output, and central bloo d volume in relation to haemodialysis. Ten uraemic patients, without c ardiopulmonary symptoms, were investigated at the beginning and end, a nd 2 h after, a regular dialysis session. A group of Is surgical patie nts about to undergo elective abdominal surgery Served as controls. De spite normal gas exchange, central blood volume, and cardiac output at the start of dialysis the mean (SD) lung water was significantly high er than in the control group [4.8 (0.9) compared with 3.6 (0.7) ml/kg, P<0.001]. There was no correlation between weight gain between sessio ns of dialysis and the magnitude of lung water at the start of dialysi s. Lung water decreased (P<0.001) to the level of the control group in response to dialysis. There was no correlation between weight loss an d reduction in lung water induced by dialysis. In conclusion, we have verified the presence of subclinical pulmonary oedema which was remove d by dialysis in a group of patients with established renal failure. T he variations in lung water cannot be explained by hydrostatic mechani sms alone.