The "gold standard" method to evaluate the mass balances achieved during dialysis for a given solute remains total dialysate collection (TDC). However, since handling over 100 liter volumes is unfeasible in our current dialysis units, alternative methods have been proposed, including urea kinetic modeling, partial dialysate collection (PDC) and more recently, monitoring of dialysate urea by on-line devices. Concerned by the complexity and costs generated by these devices, we aimed to adapt the simple "gold standard" TDC method to clinical practice by diminishing the total volumes to be handled. We describe a new system based on partial dialysate collection, the continuous spent sampling of dialysate (CSSD), and present its technical validation. Further, and for the first time, we report a long-term assessment of dialysis dosage in a dialysis clinic using both the classical PDC and the new CSSD system in a group of six stable dialysis patients who were followed for a period of three years. For the CSSD technique, spent dialysate was continuously sampled by a reversed automatic infusion pump at a rate of 10 ml/hr. The piston was automatically driven by the dialysis machine: switched on when dialysis started, off when dialysis terminated and held during the by pass periods. At the same time the number of production cycles of dialysate was monitored and the total volume of dialysate was calculated by multiplying the volume of the production chamber by the number of cycles. Urea and creatinine concentrations were measured in the syringe and the masses were obtained by multiplying this concentration by the total volume. CSSD and TDC were simultaneously performed in 20 dialysis sessions. The total mass of urea removed was calculated as 58038 and 60442 mmol/session (CSSD and TDC respectively; 3.1 +/- 1.2% variation; r = 0.99; y = 0.92x -28.9; P < 0.001). The total mass of creatinine removed was 146,941,143 and 150,071,195 mumol/session (2.2 +/- 0.9% variation; r = 0.99; y = 0.99x + 263; P < 0.001). To determine the long-term clinical use of PDC and CSSD, all the dialysis sessions monitored during three consecutive summers with PDC (during 1993 and 1994) and with CSSD (1995) in six stable dialysis patients were included. The clinical study comparing PDC and CSSD showed similar urea removal: 510 +/- 59 during the first year with PDC and 516 +/- 46 mmol/dialysis session during the third year, using CSSD. Protein catabolic rate (PCR) could be calculated from total urea removal and was 1.05 +/- 0.11 and 1.05 +/- 0.09 g/kg/day with PDC and CSSD for the same periods. PCR values were clearly more stable when calculated from the daily dialysate collections than when obtained with urea kinetic modeling performed once monthly. We found that CSSD is a simple and accurate method to monitor mass balances of urea or any other solute of clinical interest. With CSSD, dialysis efficacy can be monitored at every dialysis session without the need for bleeding a patient. As it is external to the dialysis machine, it can be attached to any ty...

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Congestive heart failure was produced in nine dogs following surgical removal of the tricuspid valve. Six dogs developed ascites with or without peripheral edema, and four dogs remained ascites-free for 5, 6, and 11 weeks (one dog in this latter group did later develop ascites 14 weeks following operation; it was therefore studied twice and included in both groups). Systolic aortic pressure, sodium balance, right atrial pressure, glomerular filtration rate, sodium para-aminohippurate clearance, plasma aldosterone, norepinephrine, renin activity, and antidiuretic hormone levels were measured in each dog before surgery and during the experimental period of the steady state of edema in the dogs of group A, and at 5, 6, and 11 weeks in the four dogs of group B. Right atrial pressure increased considerably and glomerular filtration rate and sodium para-aminohippurate clearance decreased markedly in each dog. The most significant and important findings were (1) normal sodium balance in the dogs of group B without ascites, whereas four of the six dogs with ascites had a markedly positive sodium balance; (2) increased antidiuretic hormone activity levels in all dogs with congestive heart failure and ascites in contrast with the absence of any change in the dogs without ascites. The changes in plasma aldosterone, norepinephrine, and renin activity levels were not consistent. It is suggested that the antidiuretic hormone may play a role in the formation of ascites and edema in dogs with congestive heart failure following total removal of the tricuspid valve.

The concentrations of AAA in these VGB-treated children were as high as the concentrations found in the inherited metabolic disease, AAAuria. This could lead to incorrect diagnosis and to inappropriate genetic counseling. Thus whenever a genetic metabolic disease is suspected, amino acid chromatography testing should be performed before initiation of treatment with VGB.

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