Clinical Research Directory

Fluid Currents During Hemodialysis

During dialysis, three objectives are achieved. 1. Blood is cleansed from waste products. 2. Excess water is removed. 3. Electrolytes are regulated. These processes occur simultaneously but vary from patient to patient depending on their specific needs. Some patients still produce urine, but of poor quality. Others have no residual urine production at all and require removal of fluid from both blood and tissues. Hypotension may occur during dialysis, related to intravascular hypovolemia and inadequate fluid reinfusion, which is common during ultrafiltration exceeding 400 ml/h. The amount of fluid removed is influenced by fluid recruitment from tissues. This mainly occurs in two different ways: osmotic recruitment across capillary membranes from the perivascular space or via lymphatic reflow. The proportions are not fully understood. When fluid is recruited from the perivascular space, the influx of albumin and immunoglobulins is unlikely. However, these should accompany lymph to the blood if lymphatic flow is increased. The content of albumin and immunoglobulins differs between lymph and plasma. Thus, the proportions of fluid recruitment from tissues should be calculable using mass balance calculations based on ultrafiltrate, colloid osmotic pressure, hemoglobin, albumin, and immunoglobulin concentrations. The rate and proportions of fluid reinfusion into the bloodstream are not fully understood. Therefore, in this study, the aim is to monitor fluid reinfusion and its proportions of lymph/osmotic recruitment into the bloodstream.