An investigation of transcapillary plasma refill during ultrafiltration in haemodialysis

Principal Researcher – Nicos Mitsides

Fluid imbalance is a significant problem faced by people with kidney disease. As the kidneys’ ability to control fluid balance in the body diminishes in advanced kidney failure, patients rely on dialysis to remove any excess fluid that accumulates in their body between treatments. Depending on fluid intake this can vary between 500ml to more than 3 litres. This fluid excess distributes itself primarily to the blood circulation causing high blood pressure but it equally spreads to other body spaces such as the interstitial space causing leg swelling. So although someone will be carrying an excess of 3L of fluid only part of that will be circulating in the blood. Dialysis primarily removes fluid from the blood compartment. As fluid is removed the balance between blood and the other body spaces is deranged leading to movement of fluid from the other spaces into the blood to restore the balance. This process is not automatic and there maybe a time-lag between removal and re-equilibration. If fluid is removed too quickly it could cause drop in blood pressure, dizziness, nausea, headaches and confusion. The process of fluid movement from other body spaces back into the blood is called refilling and the speed by which this happens varies between people. We want to study the speed of fluid refilling in dialysis patients using the monitoring equipment already available on dialysis machines during a standard dialysis treatment. We will also measure blood markers of the processes that control the speed of fluid refill. This study could help us identify people with slow or quick refill to enable us to personalise their fluid removal during dialysis, to avoid drops in blood pressure and thereby reduce the harmful effects associated with it.