Aerospace and Dialysis

By: Shaila Murthy

Chronic Kidney Disease affects more than 8% of the world's population, and as of right now, the only real treatment option besides a transplant (which few people are eligible for) is dialysis. End-Stage Renal Disease (also known as ESRD) is the most severe stage of CKD, and is when the kidney can no longer remove harmful substances from the blood.

Dialysis (or hemodialysis) helps patients by removing the blood from the body, filtering it out to eliminate any unwanted material, and then pumping it back into the body. The important factor here is that the dialysis machine has to take the blood from within the body, meaning it must somehow connect to the bloodstream. While a catheter is one option, it's more of a short-term solution that will have to be replaced pretty frequently. The more common and longer term solution is an Arteriovenous Fistula, which is placed in the patient's wrist or upper arm.

An AVF works by dilating and contracting to provide a method for blood to flow in and out of the body. When the AVF dilates, the blood flow increases out of the body to be purified before being sent back in. While this is a great system, it has a few fatal flaws that elicit a need for improvement. Due to unsteady blood flow patterns, around half of AVFs fail within months of their creation. The patient's artery walls inflame (known as Intimal Hyperplasia), causing the AVF to block up and fail. When this happens, most patients will go back into surgery to have it redone, however after some time they will run out of places to put the AVF. The other issue with AVF is how costly it is, meaning it is not a viable option for a large portion of the population. 

A video showing what blood flow looks like after an AVF procedure - note the irregular blood flow

CFD (Computational Fluid Dynamics), which was first used for aerospace applications, has now become an alternative to experiments performed on subjects. By using the numerical simulation, the researchers at Imperial College London were able to analyze various AVF configurations to figure out how geometry affects the success of the procedure. CFD allows the researchers to study the blood flow and any other factors necessary simply through calculations, whereas before experiments were difficult due to the inability to perform them to an extent, and thus very little data being collected. With the help of aerospace computations, AVFs can be studied and optimized for the patient, leading to a higher success rate and thus less costs for the patients or providers, making AVF procedures safer, more effective, and potentially even more affordable and accessible.

A video showing what the prototype AVF simulator would look like

Sources:

1.) Smith, Colin. "AI and Aerospace Models Used to Optimise Blood Flow in Veins." Phys.org. Science X Network, 10 Oct. 2017. Web. 12 Oct. 2017.

2.) Shankara, Prashanth S. "Blood Flow Simulations Bring Safer and Affordable Hemodialysis to the Masses." Life Sciences (n.d.): 18-21. Web. 12 Oct. 2017.