BME has discovered that blood circulates at high velocity and causes turbulence inside standard hemodialysis devices (needles, catheters, blood lines, dialysis filter) and inside the dialysis vascular access.

a)  Inside the standard hemodialysis devices, the high velocity and turbulence occurs because of the poor design of the devices and of the pump used to propel the blood.

b)  Inside the dialysis vascular access, the high velocity and turbulence occurs because of the poor design of the standard venous needle which exits the blood as a single jet of extremely high velocity and turbulence.

BME has discovered that the high velocity and turbulence of the blood inside the dialysis tubing damages blood cells, that is, white blood cells, red blood cells and platelets and the high velocity and turbulence of blood inside the dialysis vascular access damages blood cells and the inner lining of the vascular access (the endothelium or endothelial cells).

Cells are damaged by friction with each other or against the walls of tubing or the wall of the vascular access or by impact against each other or against the wall of tubing or the wall of the vascular access (friction is called a shear stress and impact is called a compression stress). Friction or impact of blood cells with each other or other cells causes:

a)   Activation or destruction of white blood cells. Activated or destroyed white cells form and release cytokines that cause inflammation (i.e. high level of C-Reactive Protein which is a marker of inflammation), loss of appetite, anemia, destruction of muscle mass, high serum phosphorus, fatigue and oxidative stress (formation oxidants). Oxidative stress in turn contributes to cause hypertension, anemia and accelerated atherosclerosis including progressive coronary arterial disease,

b) Activation  or destruction of platelets. Activated or destroyed platelets release pro-coagulants which contribute to cause clotting of micro capillary tubes of the dialysis filter. These clots prevent the circulation of blood through the tubes and this prevents the removal of toxic substance,

c) Damage or destruction of  red cells and this contributes to cause anemia.

 The single jet of high velocity of the standard venous needle causes friction or impact of cells inside the vascular access by several mechanisms:

• The high velocity jet causes turbulence and the high velocity and turbulence causes high friction of blood cells with each other and with the endothelial cells.

• The  blood cells inside the single jet moving at high velocity, impact with the blood cells  already present inside the vascular access and moving at slower velocity(the velocity of the jet is higher than the velocity of the blood inside the vascular access).

• The high velocity and turbulence causes friction of  the plasma (liquid component) and blood cells (cells component) with the cells of the inner lining of the vascular access (the endothelial cells) and this causes damage to the blood cells and to the endothelial cells.

• The single jet can impact directly on the endothelial cells and damage or destroy these cells.

Finally, BME has discovered that improving the design of devices decreases the velocity and turbulence of blood during dialysis and this decreases the damage to white cells, red cells and platelets, the inflammation and oxidation, and the damage to the inside of the vascular access.

Like Sandblasting with Cells

The effect of the high velocity jet of the standard venous needle can be compared with the effect of a power washer and of a sand blaster used to clean the façade of buildings. The fluid component of the jet – like the fluid component of a power washer – causes damage when the fluid causes “erosion” on surfaces. And, the cell component of the jet – like the sand grains in a sand blaster – cause damage when the cells impacts with each other or with the endothelial cells.

The effect that turbulence has on  the blood cells during dialysis can be compared with the turbulence occurring inside a blender filled with a fluid (i.e plasma) with particles in suspension (i.e. cells): continuous chaotic movements of the cells and multiple impacts with other cells or the walls.

Turbulent flow does not occur in normal vessels because it is harmful to cells. In turbulence, the cells have chaotic movements and multiple impacts with other cells, and the vortices and eddies of turbulent flow subject the endothelium of the vascular access and the blood cells  to large multidirectional mechanical stresses (shear and compression stresses)  that cause functional and morphological changes and activation or destruction of cells. In turbulent flow, blood cells behave like missiles colliding at high velocity against the endothelium  or against other cells.

High velocity and turbulence occur during hemodialysis because the products used in hemodialysis have been designed to transport water at a low flow rate and not blood at a high flow rate.  Even though blood is a fluid, like water, 30-40% of the blood volume is made of cells (red cells, platelets, and white cells) which are extremely fragile and damaged by high velocity or turbulence. All the blood cells in the body have many opportunities to become damaged or “activated” during dialysis because during one dialysis each blood cell circulates 500-700 times through the dialysis circuit at high velocity or turbulence.

One dialysis causes a state of acute (temporary) illness: inflammation, lack of appetite, fatigue, loss of muscle, hypophosphatemia and oxidative stress that can last for several hours after the dialysis treatment ends.

Repetitive dialysis, every other day like in patients with chronic (permanent) kidney failure  or daily like in patients with acute (temporary) kidney failure causes a state of chronic (permanent) illness: inflammation and oxidative stress, anemia, accelerated atherosclerosis and heart disease. Also, repetitive damage to the endothelium of the vascular access by the turbulent flow during repetitive dialysis contributes to cause narrowing and thrombosis of the dialysis vascular access. These medical complications contribute to cause mortality and increase the cost of care.