Good biocompatibility of the polyamide hemofilter.

Chronic hemofiltration (HF) is now a well-established method, especially for elderly uremic patients and those suffering from cardiovascular problems. This is due to the fact that chronic HF offers superior treatment comfort with less hypotensive episodes, vomiting, muscle cramps and febrile reactions. Apart from the different blood purification techniques involved in chronic HF compared to hemodialysis (i.e. convection versus diffusion), it might well be that the better treatment comfort is attributable to a certain extent to the polyamide HF membrane used in our HF treatments. We studied different biocompatibility parameters and received the following data: (a) leukocytes and thrombocytes remained unchanged during a treatment session; (b) elastase increased slightly but there was no difference between the polyamide and polycarbonate membrane, and (c) arterial and venous concentrations of C5a and C3d remained almost unchanged. The superior treatment comfort and better vascular stability of HF over hemodialysis might also be due to the improved biocompatibility of the applied hemofilter as the polyamide membrane induces no changes in different biocompatibility parameters such as leukocytes, thrombocytes, C5a or C3d.

HTLV-III antibodies in hemodialysis patients--a consequence of blood transfusions?

An investigation for HTLV-III antibodies in chronic hemodialysis patients revealed in four out of 276 patients a positive result using the ELISA and western blot techniques. All HTLV-III positive patients had received blood transfusions. As it has been shown that a needle stick could transmit the HTLV-III, it is suggested that hemodialysis patients who have received frequent blood transfusions should be screened.

The occurrence of fever during hemodialysis and hemofiltration. A comparative study.

The occurrence of fever during various blood purification methods was evaluated in a retrospective study. It could be demonstrated, that patients treated chronically by conventional hemodialysis experience six times more febrile episodes than patients on chronic hemofiltration (4.84% versus 0.81%). Since many of the increased temperatures could not be explained by conventional means, it has to be assumed that the treatment itself caused the fever, possibly activating the monocyte hormone interleukin 1. It is of further note that there was no difference in the magnitude of the temperature due to septicaemia or to no obvious cause. This finding necessitates in our opinion an early antibiotic therapy in those cases where fever develops without clear explanation.

Failure to show a temperature-dependent vascular stability during hemofiltration.

The effect of different blood temperatures on the vascular stability during hemofiltration was evaluated in 10 patients being in the regular chronic hemofiltration program. In contrast to recent data, no differences could be observed with regard to the heart rate, systolic blood pressure or mean arterial pressure, when the blood returned to the patient either with a temperature of 34.68 degrees C or 36.22 degrees C. According to these data it is therefore presently not justified to consider differences in the blood temperature as a critical determinant for the vascular stability during HF.

Chronic hemofiltration. A critical evaluation of a new method for the treatment of blood.

The experiences which have been compiled in more than 2400 hemofiltrations confirm that this method represents an alternative way of treating uremic patients. The main advantages of chronic hemofiltration are the comfort of the patient and the ease in handling excess overhydration without extending treatment time, which is less than 3 X 3 hours/week if adequate hemofilters are used. With regard to the improvement of such typical uremic complications as severe hypertension, hypertriglyceridemia or neuropathy, hemofiltration does not seem to be superior to hemodialysis. However, since most hemofiltration patients do not require phosphate binders and, additionally, remarkable amounts of parathyroid hormone are removed during one hemofiltration, it appears possible that hemofiltration might be an important therapeutic alternative for those renal patients who suffer from severe hyperphosphatemia and secondary hyperparathyroidism.

Clinical aspects of hemofiltration.

We report on clinical experiences obtained in 7 uremic patients treated since January 1976 3 times weekly by chronic hemofiltration. The observations which we collected in more than 300 treatments suggest that hemofiltration might be superior to conventional hemodialysis. The main advantages of this treatment are characterized by its better control of hypertension, hyperhydration, and possibly of uremic bone disease. Furthermore, the applied acrylonitrile membrane allows the removal of substances with a molecular weight up to 60,000, similar to the glomerular basement membrane. Additionally, we report on methodological problems, on the compatibility of hemofiltration, and finally on its efficiency for removal of different uremic solutes.

The hemofiltration system: variations of the negative pressure.

The physical conditions of the hemofiltration process are briefly discussed to describe the applied system that is characterized by a negative pressure pump which is directly attached behing the filter. A schema is presented that shows the characteristics of a fully automatic hemofiltration apparatus that is presently in development.

Parathyroid hormone-, 25-OH-vitamin D-, and digoxin levels in patients treated by chronic hemofiltration.

Immunoreactive parathyroid hormone (iPTH) was measured in the serum and filtrate before, during and after hemofiltration. iPTH regularly declines during hemofiltration; one patient, investigated for a longer period, showed a normalization of iPTH serum level with this treatment. The iPTH values found in the hemofiltrate were remarkably high, a finding that could be explained by non-specific effects, by the occurrence of hormone fragments or by an increased secretion rate. At any rate, the results suggest a filtration of parathyroid hormone and/or hormone fragments. On the other hand, it was impossible to detect any 25-OH-vitamin D in the hemofiltrate. Finally, digoxin could be found in the filtrate, but only in very low concentrations.