step 1 - arteriovenous fistula. A blood vessel is made by connecting a vein and an artery.
step 2 - 2 thin needles inserted into AV fistula, one for entry, one for exit.
haemodialysis patients are usually restricted in their fluid intake because the machine can not remove 2-3 days worth of fluid. usually 2-3 pints a day are allowed. with kidney dialysis, sodium, phosphorus, and potassium are also restricted because the kidneys are not filtering them.
the contents of a dialysis solution can be changed based on the levels of certain minerals in the blood and if side effects occur.
anticoagulants are used to keep blood flowing during treatment.
diffusion of solutes across a semi-permeable membrane. counter current flow...
ultra purified water is mixed with concentrated dialysate. dialysate is electrolytes mixed with an acid solution, which is then mixed with the water and a chemical buffer (a solution that allows for very small changes in pH). this diasylate solution conducts electricity. the pH can be changed with bicarbonate or lactate as chemical buffers.
the blood flow rate is usually between 200-400mL per minute.
the dialyzer is the machine. it uses a cylinder of semi-permeable hollow fibers. the blood goes throw the fibers, and the dialysate surrounds them. pressure gradients are used to pump the blood through.
the membranes used in dialyzers can have different pore sizes. the filtration of different pore sizes results in different things being filtered. originally, cellulose from cotton liner was used, but this activated complement (the enhancing of the immune response and inflammation) in the blood. some different techniques were used to fix this problem. cellulose acetate and modified cellulose are still used. there are also synthetic membranes made from polymers such as polyarylethersulfone, polyamide, polyvinylpyrrolidone, polycarbonate, and polyacrylonitrile. they activate complement much less but absorb more protein due to being hydrophobic and can therefore still lead to activated complement. they are usually high-flux (larger pore size). membranes always have a variety of pore sizes, which may let some things through that are unwanted. nanotech is being used to assist with this.
there is some evidence that those with coexisting conditions have better mortality rates when using high flux.
larger dialyzer = more filtration, generally.
haemofiltration is usually used in an intensive setting. similarly to dialysis, it uses a semi-permeable membrane to filter fluid and waste products. it then adds fluid to the blood before returning it to the patient. unlike dialysis, it uses convection instead of diffusion. convection is the movement of fluids due to internal or external forces present on the components. haemofiltration usually removes larger solutes, compared to dialysis. a positive hydrostatic pressure moves the solutes across the membrane.
sometimes, haemofiltration and haemodialysis are combined (haemodiafiltration) to remove both large and small solutes. haemofiltration usually uses a central line because needles could cause damage. The blood flow rate is lower than dialysis, at around 100-200mL per minute.
magnetic filtration to isolate cells affected with blood disease. human trials have not yet been done, but it appears promising. this aims to address the problems faced by using medications, such as toxins left in the blood.
artificial-liver blood-purification system (ALS) aims to reduce the cytokine storm in CoViD-19 patients. this ideally reduces the intensity of cytokines released and hopes to suppress the progression of the disease. promising results in reducing cytokines. “plasma replacement, plasma adsorption, and blood/plasma filtration” is usually used to treat liver failure.
is there an a) cheaper, b) more efficient, c) less disruptive, and/or d) less risky way to treat blood-borne diseases such as some STIs, malaria, sepsis, autoimmune diseases, etc.? can an extracorporeal machine such as a dialyzer, haemofilter, magnetic filter, absorption material filtration, or centrifugation be used for this process? if so, what would it be? how would it be designed and used? what procedures would a patient have to undergo? how many treatments would it take, or would it have to be continuous over time? what are the potential side effects and risks? what would the limits be?