Is PTFE filter membrane the best choice during hemodialysis?

The filtration principle of PTFE membrane in hemodialysis depends on its microporous structure and the principle of size exclusion. The PTFE filter membrane acts as a barrier through which the blood passes and filters to remove waste and excess fluid.

First, the pore size of the membrane is critical to its effectiveness in hemodialysis. PTFE membranes typically have a pore size between 0.1 and 10 microns. This size range is critical because red blood cells, the most abundant cells in blood, are about 7-8 microns in diameter, while white blood cells are about 12 microns in diameter. Thus, a pore size of about 0.1 to 1 micron is effective for trapping any large blood cells while still allowing small solutes to pass through the membrane.

Second, the principle of size exclusion is crucial to the effectiveness of PTFE membranes in removing impurities from blood. Smaller solutes, such as urea and creatinine, can pass through the pores of the membrane and are removed from the blood, while larger proteins, such as albumin, cannot pass through the pores and remain in the blood.

Additionally, the hydrophobic nature of PTFE filter membranes is advantageous in hemodialysis because it repels water and other fluids, preventing the membrane from becoming clogged or saturated with fluid during filtration.

PTFE (polytetrafluoroethylene) is a commonly used hemodialysis filter membrane material because of its good biocompatibility and resistance to biofouling. However, there are other materials that can be used as alternative filter membranes for hemodialysis. These include cellulose-based membranes such as regenerated cellulose and cellulose acetate, as well as synthetic materials such as polyethersulfone (PES), polyacrylonitrile (PAN) and polyamide (PA). The choice of hemodialysis membrane material depends on several factors such as biocompatibility, pore size, filtration efficiency, and durability. Here are some general considerations for choosing between PES, PTFE, PAN and PA:

1. Biocompatibility: All four materials have good biocompatibility and are used for hemodialysis membranes.

2. Pore size: PTFE and PES membranes have small pore size, which may be more suitable for removing small molecular weight toxins. PAN and PA membranes have larger pore sizes, which may be better for removing larger molecular weight proteins.

3. Filtration efficiency: All four materials have good filtration efficiency, but PES membrane is known for its higher adsorption capacity and greater removal of toxins.

4. Durability: PTFE and PES membranes are more durable than PAN or PA membranes and are less prone to degradation over time.

5. Cost: PTFE and PES membranes are more expensive than PAN and PA membranes, but they can provide better filtration and longer-lasting advantages.

The choice of material depends on a variety of factors such as the patient's medical condition, individual patient needs, preferences, and the availability of specific types of membrane materials in the hemodialysis center, the level of blood purification required, and the cost-effectiveness of the material. Each material has its own advantages and disadvantages, and the choice of material is made after consideration of all these factors, by the attending physician in consultation with other healthcare professionals involved in the patient's care.

Overall, the combination of microporous structure, hydrophobicity and size exclusion principle of PTFE filter membrane enables it to effectively remove impurities and excess fluid in blood during hemodialysis. The size of impurities removed can vary, but typically includes solutes such as urea, creatinine, and other toxins that are present in the blood due to kidney failure or other conditions.

Citation

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2.Cheung AK, Levin NW, Greene T, et al. Effects of randomization to hemodialysis with high-flux membranes on mortality and morbidity: results from the HEMO Study. J Am Soc Nephrol. 2002 Apr;13(4):1213-24.

3.Schindler R, Krause B, Weibler A, et al. Synthetic polyamides for hemodialysis membranes: pore formation and biocompatibility. Biomaterials. 1996 Jun;17(11):1109-17.

4.Polak-Jonkisz D, Augustyniak-Bartosik H, Kędzierski K, et al. Improved biocompatibility of hemodialysis membranes containing polyethersulfone/polyvinylpyrrolidone blend. Artif Organs. 2010 Feb;34(2):167-75.