How A Dialysis Machine Performs the Function of the Kidneys

The kidneys filter waste and excess water out of the blood. Dialysis is a medical procedure that performs the function of the kidneys artificially. Below we explain the mechanics of dialysis. 

Types of Dialysis 

As described on several websites, there are two types of dialysis. Circulating the blood from the body through a filter then back into the body. This method is hemodialysis. A fistula is the surgical merging of an artery and a vein. A fistula is an outlet for the blood to enter the dialysis machine during hemodialysis. 

Peritoneal dialysis involves the implantation of an abdominal catheter. The catheter is a means to deliver a dialyzing solution into the abdomen. The dialyzing solution filters the blood as blood passes through the abdominal cavity. The last step is to drain away the dialyzing solution. 

The Dialysis Machine 

Dialysis machines, of which the Baxter Dialysis Machine is one example, were once called artificial kidneys. As blood enters the dialysis machine it passes through an arterial pressure monitor. The monitor sounds a warning if the pressure is too high or too low. A blood pump keeps the blood circulating through the machine. Next, the blood is sent to a heparin pump. Heparin is an anticlotting agent. Next, the blood passes through an inflow pressure monitor. 

The Dialyzer 

From the inflow pressure monitor, the blood enters the dialyzer. Inside the dialyzer, there is a porous membrane or filter. The filter pores vary in size. Waste in the blood passes through the smaller membranes and are routed into a container outside the dialysis machine. The larger pores allow proteins and red blood cells to return to the patient. 

As blood enters the membrane on one side a dialysis solution is pumped into the other side of the membrane from an external source. The dialysis fluid serves two purposes. It infuses the blood with potassium and calcium. Secondly, the dialysis fluid helps the membrane to more effectively filter urea, creatinine, and other waste from the blood. 

During the final phase of dialysis, the blood goes through a venous pressure monitor. Just before the blood returns to the patient it passes through a device that checks the level of air in the blood. If needed the device purges the blood of excess air. 

The First Dialysis Machines 

Dr. Willem Kolff developed the first artificial kidney in Holland during the 1940s. At the end of the 1940s, Kolff had joined the staff of Mount Sinai Hospital. In the 1950s Kolff had perfected a dialysis machine to treat acute kidney failure. Treatment for end-stage renal disease (ESRD) was still needed. 

Dialysis became a means to treat ESRD when Dr. Belding Scribner conceived a forerunner to the fistula the Scribner shunt. The fistula was pioneered in 1966 by Dr. James Cimino and Dr. MJ Brescia. Scribner opened the first dialysis clinic. He also developed the first in-home dialysis machine in 1973.

 

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