Infusion Sets vs Transfusion Sets: Types and Pore Sizes of Filters

Infusion Sets

Currently, there are essentially three types of infusion sets used in clinical practice: one is the regular PVC infusion set with a filter pore size of15μm; another is the precision infusion set that contains PVC with filter pore sizes of3μm,5μm, or even smaller; and the third one is the TPE infusion set without PVC plasticizers and a filter pore size of15μm, which can prevent absorption of emulsions and oil-based medications such as nitroglycerin, dibutyl phthalate injection, and certain chemotherapy drugs.

Transfusion Sets

Currently, 90% of domestically produced infusion set tubing and blood transfusion funnels are made of polyvinyl chloride (PVC), with filter pore sizes ranging from170μm to260μm. If the pore size is too small, it is easily blocked by microaggregates of platelets and white blood cells in the blood, affecting the effective filtering surface area.

Infusion Sets vs Transfusion Sets: Concentrated Red Blood Cells and Medications

The diameter of a single red blood cell is about6 to 9µm. However, concentrated red blood cells, having the majority of plasma, platelets, and white blood cells removed, have increased red cell concentration, causing many red cells to stick together. Therefore, the viscosity of concentrated red cells is higher than whole blood, with fluidity being only60% of that of whole blood.

Requirements for Infusion Sets for Various Medications

Infusion of Chinese patent medicines

Due to impurities present during preparation or insufficient dissolution of powder drugs, the number of particles can increase. Therefore, a precision infusion set with a drug filtration device should be used, with a pore size of 2.2 to 5μm, and drug adsorption of<28.6% is preferred.

Nutritional agents

The US 2016 INS filter provisions suggest using a0.2µm filter for filtering non-lipid parenteral nutrition solutions, and a1.2µm filter for lipid-containing emulsions. The filters should be replaced every24 hours.

Y-Type Infusion Set: Particle Contamination and Filters

In the 2016 US INS filter provisions, continuously updated research evidence suggests that particles (such as rubber, glass, latex) can affect capillary endothelial cells. Small bubbles in the liquid can cause ischemia in the brain and lungs; the use of filters with particle retention and air elimination functions can prevent potential damage from air/particles (such as heart defects with right-to-left shunts).

Intravenous particles are non-metabolic particulate impurities in the liquid, most of which have a diameter of 1 to 15µm. A few can range from 50 to 300µm. Larger particles can cause local vascular occlusion or insufficient blood supply, tissue hypoxia, phlebitis, and edema, granulomas, or even trigger tumor formation. Insoluble particles can also cause allergic reactions and pyrogen-like reactions.

Adsorption Effects of PVC Material Blood Transfusion Sets on Drugs

PVC material has a strong adsorption capacity for some alcohol-soluble and fat-soluble drugs, causing inconsistencies in prescribed medications and affecting therapeutic efficacy. These drugs include paclitaxel, nitroglycerin injection, isosorbide mononitrate injection, nimodipine, clonazepam, diazepam, chlorpromazine, urokinase, insulin, fat emulsion, oil of dishcorea bulbifera, ferulic acid, amiodarone, fentanyl, tinidazole, curcuma zedoaria oil, etc.

In summary, given the blood transfusion set's PVC material and relatively large filter pores, it shows thatblood transfusion sets are specially designed for blood and its products, making them unsuitable for infusions.