J.P. van Hooff

Echography of the Inferior Vena Cava is a Simple and Reliable Tool for Estimation of ‘Dry Weight’ in Haemodialysis Patients

Using echography, the diameter of the inferior vena cava (IVC) and its decrease on deep inspiration (collapse index) were evaluated in haemodialysis patients. The diameter of the IVC was expressed as an index to the body surface area (VCD) in mm/m2. Non-linear regression analysis in predicting mean right atrial pressure by VCD (mm/m2) and collapse index revealed a good correlation (r = 0.92; P less than 0.001) in both measurements. These results indicate that the IVC indices can be used as a parameter for both high and low filling pressures. Over-hydration (mean right atrial pressure greater than 7 mmHg) was defined as a collapse index of less than 40% and a VCD of more than 11.5 mm/m2, and underhydration (mean right atrial pressure less than 3 mmHg) as a VCD of less than 8 mm/m2 and collapse index of above 75%. In 22 patients in whom dry weight was determined on clinical grounds, only six had a correct dry weight according to IVC indices. Reliability of IVC indices for estimation of body fluid status was proved by the fact that during haemodialysis with fluid removal, postdialysis underhydrated patients according to IVC indices showed a decrease of mean arterial pressure and stroke volume, and an increase of heart rate. No such changes were observed in postdialysis normovolaemic and hypervolaemic patients, according to the vena cava indices. Furthermore, blood volume in normo- and hypervolaemic patients decreased much less than in hypovolaemic patients, despite the same amount of ultrafiltration. Total blood volume (ml/m2) and VCD (mm/m2) correlated significantly (r = 0.61; P less than 0.001), whereas there was no significant correlation between collapse index and blood volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular reactivity during combined ultrafiltration-haemodialysis: influence of dialysate sodium

BACKGROUND It is well known that vascular reactivity is impaired during combined ultrafiltration-haemodialysis as compared to isolated ultrafiltration and haemofiltration, which might be related to differences in plasma osmolality. Therefore vascular reactivity was studied during combined ultrafiltration-haemodialysis in relation to sodium-related differences in plasma osmolality/tonicity. METHODS With each patient serving as his or her own control, nine stable dialysis patients (23-71 years) were studied during 2 h of combined ultrafiltration-haemodialysis (bicarbonate; UF rate 1.0 l/h)) at two different dialysate sodium concentrations: 134 and 144 mmol/l. Before dialysis as well as every 20 min during dialysis, blood pressure (Dinamap), heart rate (ECG), and forearm vascular resistance and venous tone (strain-gauge plethysmography) were measured. Relative blood volume was monitored continuously by an optical reflection method (Haemoguard 2000), while before and after dialysis blood was obtained for the estimation of plasma prostaglandin E2. RESULTS High-sodium dialysis resulted in a significantly higher post-dialysis plasma sodium concentration (139. 9 vs 135.0 mmol/l; P<0.01) while the decrease in relative blood volume was significantly smaller as compared to low-sodium dialysis (-8.4 vs -18.4%; P<0.01). There were no significant differences in the different haemodynamic parameters between the two treatment modalities. Both high- and low-sodium dialysis were associated with a significant increase in forearm vascular resistance while venous tone remained unchanged. Although there was no significant difference in plasma PGE2 between the two treatment modalities, PGE2 increased significantly only during low-sodium dialysis. We found no relationship between changes in PGE2 and vascular reactivity. CONCLUSIONS We conclude that vascular reactivity during combined ultrafiltration-haemodialysis is not directly influenced by sodium-related changes in plasma tonicity. Although not directly studied, the reported improved haemodynamic stability with high-sodium dialysis is probably only mediated through a better preservation of plasma volume. Finally, an increase in plasma PGE2 as observed during low-sodium dialysis does not lead to a decrease in vascular tone.

Nutritional considerations in renal transplant patients.

In renal transplant patients, weight gain generally increases after renal transplantation, which will be influenced by improved appetite and a reversal of the uremic state. However, at least in the early posttransplant period, the increase in body weight is mainly due to an increase in body fat mass. This phenomenon may be partly due to relatively high doses of steroids in the early period after renal transplantation, possibly mediated by their inhibiting effect on lipid peroxidation, but also appears to be related to physical inactivity. The increase in body fat mass may contribute to posttransplant hyperlipidemia, which is improved but not completely normalized by dietary intervention. Current dietary recommendations in stable renal transplant patients do not generally differ from those of the general population, although intense dietary counselling may be indicated in patients with excessive posttransplant weight gain. The effect of supervised exercise training on body composition is currently under investigation.

Chronic haemodialysis with bicarbonate dialysate: technical and clinical aspects

Bicarbonate as a physiological buffer should be preferred in haemodialysis treatments. The use of bicarbonate dialysis, however, varies from 30 to 100% in the different industrialised countries. Except for the many advantages using bicarbonate dialysate, there are also clinical pitfalls in the use of the bicarbonate buffer substrate. Furthermore, technical problems can be expected in the use of varying dialysate bicarbonate concentrations, as in the concomitant use of acetate and bicarbonate dialysate in the same dialysis unit. This paper deals with the clinical and technical aspects of bicarbonate dialysis.

Recombinant Human Erythropoietin and Its Effects on Macro- and Microcirculation during Normovolemia

In 9 chronic hemodialysis patients, treated with recombinant human erythropoietin (rHuEpo), longitudinal studies were performed to investigate possible changes in macro- and microcirculatory parameter

Long-Term Effects of Recombinant Human Erythropoietin on Macro-and Microcirculation in Chronic Hemodialysis Patients

Recombinant human erythropoietin therapy (ReHuEpo) at short term leads to an increase in systemic vascular resistance and to a decrease in cardiac index and skin microcirculatory flow. Long-term adaptive changes might occur. We studied the effects of ReHuEpo therapy on macrocirculation and skin microcirculation in 8 normotensive and normovolemic hemodialysis patients before and after, respectively, 4 and 14 months of treatment. The reported macrocirculatory changes at short term were at long term not significantly different as compared with the initial values. The mean arterial pressure remained unaltered, as might be explained by the slow correction of the hematocrit and the decrease in cardiac output in all initially long-lasting normotensive patients who were maintained normovolemic. Left ventricular end-diastolic dimensions decreased, and also the left ventricular muscle mass decreased, depending on the initial left ventricular muscle mass. The skin oxygenation improved, whereas the maximal capillary flow decreased both at short- and long-term ReHuEpo treatment. The number of capillaries in the nail fold remained unchanged. However, the percentage of tortuosity decreased significantly during ReHuEpo therapy.