This article aims to provide an overview of the process of hemodialysis and peritoneal dialysis with a particular focus on how a hydraulic circuit works inside a dialysis machine.
Below is a brief summary:
- Processes of peritoneal dialysis and hemodialysis
- Hemodialysis pumps inside the hydraulic circuit
- Fluid-o-Tech haemodialysis pumps
In a healthy person, the kidneys filter the blood, removing impurities and expelling them from the body as urine. The kidneys basically remove waste from the blood and guarantee the correct electrolyte of the body. If they do not work properly, dialysis is needed to replace this process.
There are two main types of dialysis treatment:
- This technique involves the permanent application of a catheter to the patient's abdomen to reach the inside of the peritoneal cavity. A liquid (dialysis fluid), consisting of salts and glucose, is introduced through the catheter. The peritoneal membrane, in turn in contact with the dialysis fluid, acts as an osmosis filter, allowing the exchange of electrolytes and the elimination of toxins. After the contact period, the liquid is discarded and replaced with fresh liquid for a number of cycles which normally last about 8 hours
- It usually takes place at the patient's home, preferably at night
- Efficiency is limited by the peritoneal membrane filtering capabilities
- The technique consists in connecting the patient, via a vascular access, to a circuit which sucks the blood through a pump and pushes it into a special filter which functions as an artificial kidney, allowing the transfer of waste from the blood to the dialysis fluid; after passing the filter, the purified blood returns to the patient's body through a second cannula needle usually inserted in the same arm. The process of blood extraction, preparation and circulation of the dialysis fluid is managed by complex equipment called "dialysers"
- This type of procedure takes about four hours and is performed three times a week in hospitals or specialised centres
- The removal of uremic toxins is particularly effective even for patients with a stage of complete loss of renal function
In a haemodialysis machine there is a blood circuit, intended to circulate the patient's blood through the extracorporeal circulation lines, and a hydraulic circuit, designed to manage the dialysis fluid.
In a haemodialysis machine, the pumps in the hydraulic circuit inside the equipment have 4 main functions:
- Pressure pump - to supply the dialysis fluid to the dialyzer (filter)
- Discharge pump - to remove waste dialysis solution from the dialyzer. Precise speed control is needed here to optimise the pressure gradient across the membrane
- Degassing pump - to remove air pockets from the solution
- Concentrate pump - for precise delivery of electrolytes into the fluid flow to achieve and maintain the concentrations of the clinical prescription
The pumps operate during the entire dialysis cycle with fluid at a temperature of 38° C to prevent thermal shock to the patient.The quietness of the pump is an essential element.
Dialysis machines are disinfected after use - typically citric acid and temperatures of 95°- 120° C for at least 20 minutes (depending on the machine).
Stability of performance, maintenance of vacuum and differential pressures are essential for the operation of the process.
The chemical and biological quality of the dialysis fluid is crucial. Water, specially treated with reverse osmosis equipment is filtered, degassed and carefully mixed with electrolytes to create the dialysis fluid, which then comes into direct or indirect contact with the patient. Fluid-o-Tech pumps, valves and sensors are essential for the accurate and safe handling of fluids within dialysis systems.
Fluid-o-Tech is a world leader in the design and manufacture of positive displacement pumps and fluidic solutions in the medical sector. We offer technical solutions for all those devices where hydraulic parameters are critical for safety and performance requirements.
We are the ideal partner to develop fluidic solutions for use in medical devices together with our customers. Thanks to our experience, know-how, commitment and passion we bring hope to patients for a better future.
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