Dialysis machines are used to treat patients with kidney failure, cleaning their blood of excess fluids, toxins, and electrolytes. The three primary types of dialysis are clinical dialysis, home hemodialysis, and peritoneal dialysis.
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This article summarizes each type of dialysis, outlining their flow rates, fluid requirements, sizes, and temperatures. It also outlines why valveless piston pumps are the most ideal option for a new dialysis machine.
Clinical Dialysis
Dialysis is typically performed in a hospital or clinical dialysis center, where a patient’s blood is drawn through an access point, filtered through a dialysis machine, and then returned to the body.
These machines include a blood pump, a dialyzer, and a control system. The dialyzer—essentially a hollow fiber membrane—filters the blood to remove waste and excess fluids. In clinical hemodialysis, the blood flow rate typically ranges between 300 and 500 mL per minute.
Home Hemodialysis
Home hemodialysis (HHD) is a form of dialysis performed by the patient or a caregiver in a home setting. These machines are smaller and more compact than those found in clinical dialysis centers, typically operating at a flow rate of 200–300 mL/minute.
Like their clinical counterparts, home hemodialysis machines include a blood pump, dialyzer, and control system—but their streamlined design makes them more suitable for home use.
To ensure patient safety, these machines are equipped with a water purification system that removes potentially harmful impurities. Many home systems feature built-in reverse osmosis (RO) units, which use a semi-permeable membrane to filter out contaminants, producing high-quality water for dialysis on-site.
Regular servicing and maintenance are essential to keep the RO system functioning properly and to ensure that water quality sensors are accurate.
Another critical feature of home hemodialysis machines is their self-cleaning capability. After each treatment, the machine performs a cleaning cycle to prevent cross-contamination. This process typically involves circulating a disinfectant solution through the system’s tubing, filters, and dialyzer to eliminate bacteria and viruses.
Some models offer automated cleaning and disinfection cycles using heat, chemicals, or a combination of both. These automated processes tend to be more effective than manual cleaning and significantly reduce the risk of contamination between sessions.
Peritoneal Dialysis
Peritoneal dialysis (PD) is performed inside the patient’s abdomen rather than involving direct access to the bloodstream.
A catheter is used to infuse dialysis solution into the peritoneal cavity, where it stays for several hours. During this dwell time, waste products and excess fluids pass from the blood into the dialysis solution. The fluid is then drained and replaced with fresh solution, repeating the cycle.
PD machines are generally smaller and simpler than both clinical and home hemodialysis systems. Since the process doesn't involve circulating blood outside the body, a blood pump isn’t required. Flow rates for PD are much lower, typically in the range of 10–20 mL/minute.
Fluids and Temperatures
Different fluids are used in each type of dialysis. A dialysate fluid solution is common in clinical and home hemodialysis. This solution contains electrolytes and other components that help remove blood toxins. The temperature of the dialysate solution is usually around 37 °C.
In PD, the dialysis solution is glucose-based, with a typical temperature between 20–22 °C.
When selecting a pump for a next-generation dialysis machine, key factors include required flow rates, fluid type, operating pressure, and pump accuracy.
The most widely used pump type for dialysis machines is a positive displacement pump, known for delivering a precise and constant flow rate. Among these, valveless piston pumps are a popular choice due to their high accuracy and flow rate capabilities.
Choosing the Right Pump
Valveless piston pumps generate flow using a reciprocating and rotating motion. Valveless piston pumps from Fluid Metering offer precise, consistent flow rates over a wide range of pressures.
These pumps can administer a range of fluids, including saline, dialysate, and water, while offering a long lifespan with the ability to reliably operate for many years with minimal maintenance.
When choosing an appropriate valveless piston pump for a dialysis machine, it is important to consider pressure, flow rate, and fluid compatibility requirements. The pump must be able to effectively accommodate the required flow rate for the specific dialysis treatment, as well as deliver the fluid at the required pressure.
Other considerations when choosing a valveless piston pump for a dialysis machine include the pump's power consumption, size, and noise level. It is important that the pump delivers the required flow rate and pressure while being compact enough to fit within the dialysis machine.
It should also be quiet enough to prevent disturbance to the patient during treatment and consume minimal power to keep operating costs low.
Summary
A valveless piston pump is the most ideal solution for next-generation dialysis machines. Valveless piston pumps from Fluid Metering confidently meet next-generation dialysis machines’ flow rate and pressure requirements while offering high accuracy and precision.
These factors make valveless piston pumps from Fluid Metering the best choice of pumping technology for any dialysis machine.
Acknowledgments
Produced from materials originally authored by Stephanie Moreau and Colin Rademacher from Fluid Metering, Inc.
About Fluid Metering, Inc.
Fluid Metering, Inc. (FMI) is a worldwide leader in life science pumps and dispensers, having pioneered the first valve-less piston pump over 64 years ago. With specialized expertise in fluidics and applications, Fluid Metering, Inc. supports instrument developers in tackling complex fluidic challenges.
Committed to innovation through collaboration, Fluid Metering, Inc. advances health, sustainability, and quality of life. ISO 9001:2015 certified.
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