On-line monitoring of hemodialysis sessions requires a non-invasive estimation of the parameters concerning the patient's status and the dialyzer performances. We describe here a model based on a new method for non-invasive dialysance and patient conductivity measurements. In this technique the same probe measures alternately the conductivity at the dialysate inlet and outlet for two different dialysate conductivity values. From these data, an appropriate model allows to determine the patient's conductivity as well as the effective dialysance of ionised solutes, that is to say the dialysance corrected for recirculation. A strong correlation is evidenced between the effective dialysance measured by this method and the urea clearance measured by conventional methods (r = 0.98 for in vitro solutions; r = 0.82 in vivo situations).

These data suggest that CSA nephrotoxicity could result from individually determined susceptibility and that hypertriglyceridemia may have a negative impact on renal function and cardiac mortality. The risk of cardiac mortality is increased in heart transplant patients with ESRF. The hypothesis of accelerated atherosclerosis in ESRF patients after heart transplantation leading to higher cardiac mortality incidence needs further study.

A new biofeedback module (BM) is designed for optimization of dialysate conductivity during hemodialysis sessions. Based on information on treatment time, body weight, desired weight loss of the patient, and on measurements of the effective conductivity of the patient automatically performed by the BM without necessity of blood sampling, the conductivity of the dialysate is fully controlled during the dialysis session without any intervention of the staff. 133 dialysis sessions using the BM have been performed with a bicarbonate dialysate. There was a negative correlation (r = -0.8; p < 0.001) between the mean dialysate conductivity prescribed by the BM during the session and the predialytic plasma sodium level. Despite a great variability of the predialytic plasma sodium concentration, the postdialytic plasma sodium concentration was always close to 140 mmol/l. Thus, the BM allows routine implementation of kinetic modeling for automatic determination of dialysate conductivity by adjusting it to the predialytic plasma sodium concentration.

The aims of the present study were to determine plasma endothelin (ET) in chronically uraemic patients, the renal clearance of endogenous ET in normal dog and man, and the effect of acute volaemic expansion on ET. The mean plasma ET concentration in haemodialysis patients was 57.5 +/- 5 pg/ml before haemodialysis and remained unchanged at 52.5 +/- 5 pg/ml after haemodialysis. They were thus significantly elevated both before and after haemodialysis (P less than 0.01) compared with plasma ET in normal subjects of 20.8 +/- 0.8 pg/ml. There was no evidence of ET clearance across the cuprophane membrane of the dialyser. Resting plasma ET values in the 15 non-dialysed uraemic patients ranged between 20 and 52.5 pg/ml (mean 38.2 +/- 2.3 pg/ml), significantly greater than those observed in controls (P less than 0.01). In CAPD patients, plasma ET was also significantly (P less than 0.01), elevated (63 +/- 10 pg/ml) when compared to controls, and similar to those observed in patients before haemodialysis. In dogs, mean ET did not diminish between the aorta and the renal vein (28.1 +/- 1 versus 28.4 +/- 2 pg/ml). In man mean ET did not significantly decline between the renal artery and the renal vein (17 +/- 3 to 13 +/- 0.8 pg/ml). In the seven healthy subjects who received 2000 ml of isotonic saline intravenously ET remained unchanged (24 +/- 2; 23 +/- 1 and 23 +/- 2 pg/ml before and 1 and 2 h after starting hydration respectively). We have thus shown that plasma ET is elevated in patients with chronic renal failure especially those on dialysis and CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)