http://repub.eur.nl/res/aut/6123/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/9930/ 2002-01-01T00:00:00Z BACKGROUND: Intradialytic morbid events such as hypotension and cramps during haemodialysis are generally treated by infusion of iso- or hypertonic solutions. However, differences may exist between solutions with respect to plasma refilling and vascular reactivity. METHODS: We compared the effect of no infusion (NI) with isovolumetric infusion of isotonic saline 0.9% (IS), saline 3% (HS), isotonic glucose 5% (IG), glucose 20% (HG) and mannitol 20% (HM), in six patients during the first hour of six standardized haemodialysis sessions with ultrafiltration. Relative blood volume was monitored continuously by measurement of the intravascular amount of protein. Blood pressure was measured by an oscillometric method, while cardiac output was measured by a thoracic impedance technique. RESULTS: At baseline, no differences in serum urea, sodium, potassium, glucose and osmolarity were found between the various infusion experiments. The maximum increase in relative blood volume directly after infusion was significantly greater with HG (5.1+/-0.7%) than with all other infusions (P<0.05). Stroke volume increased (21.0+/-19.2%, P<0.05) and total peripheral resistance decreased significantly (15.4+/-16.4%, P<0.05) after HG infusions. CONCLUSIONS: Infusion of hypertonic glucose during dialysis results in a greater increase in relative blood volume (RBV) than equal volumes of other solutions. As mannitol has the same osmolarity, molecule mass and charge, the greater increase in RBV following hypertonic glucose appears to be a specific effect, possibly related to a decline in vascular tone. It is therefore uncertain whether the observed increase in plasma volume during hypertonic glucose infusions will be of clinical benefit. http://repub.eur.nl/res/pub/9367/ 2000-01-01T00:00:00Z BACKGROUND: A decrease in blood volume is thought to play a role in dialysis-related hypotension. Changes in relative blood volume (RBV) can be assessed by means of continuous haematocrit measurement. We studied the variability of RBV changes, and the relation between RBV and ultrafiltration volume (UV), blood pressure, heart rate, and inferior caval vein (ICV) diameter. METHODS: In 10 patients on chronic haemodialysis, RBV measurement was performed during a total of one hundred 4-h haemodialysis sessions. Blood pressure and heart rate were measured at 5-min intervals. ICV diameter was assessed at the start and at the end of dialysis using ultrasonography. RESULTS: The changes in RBV showed considerable inter-individual variability. The average change in RBV ranged from -0.5 to -8.2% at 60 min and from -3.7 to -14.5% at 240 min (coefficient of variation (CV) 0.66 and 0.35 respectively). Intra-individual variability was also high (CV at 60 min 0.93; CV at 240 min 0.33). Inter-individual as well as intra-individual variability showed only minor improvement when RBV was corrected for UV. We found a significant correlation between RBV and UV at 60 (r= -0.69; P<0.001) and at 240 min (r= -0.63; P<0.001). There was a significant correlation between RBV and heart rate (r= -0.39; P<0.001), but not between RBV or UV and blood pressure. The level of RBV reduction at which hypotension occurred was also highly variable. ICV diameter decreased from 10.3+/-1.7 mm/m(2) to 7.3+/-1. 5 mm/m(2). There was only a slight, although significant, correlation between ICV diameter and RBV (r= -0.23; P<0.05). The change in ICV-diameter showed a wide variation. CONCLUSIONS: RBV changes during haemodialysis showed a considerable intra- and inter-individual variability that could not be explained by differences in UV. No correlation was observed between UV or changes in RBV and either blood pressure or the incidence of hypotension. Heart rate, however, was significantly correlated with RBV. Moreover, IVC diameter was only poorly correlated with RBV, suggesting a redistribution of blood towards the central venous compartment. These data indicate that RBV monitoring is of limited use in the prevention of dialysis-related hypotension, and that the critical level of reduction in RBV at which hypotension occurs depends on cardiovascular defence mechanisms such as sympathetic drive.