Hello Everyone,

I was hoping someone might be able to help us on a problem we have recently
encountered in one of our research projects. The project uses a
multi-lumen catheter (6 lumens) where only the center lumen is used to
deliver liquid and the 5 surrounding lumens are used to deliver oxygen gas.
The catheters are approximately 5 - 5.5 feet in length and the center
lumen in question is 0.012 inches in diameter at the thickest part of the
catheter (where the syringe containing liquid is attached). The catheters
do not have a constant diameter throughout their length. Some are tapered
down over the entire length where some are only tapered over the last 15
inches (furthest away from the syringe end). The distal end of the
catheter (proximal end would be considered the end where the syringe is
located) is also manually drawn down to a fine tip where the center lumen
would have a final diameter of 50 - 70 micrometers. Recently, we have
experienced some major clogging of the liquid lumen with the catheters
which are tapered over the final 15 inches. We thought that these
catheters would be much better in terms of fluid dynamics/mechanics as
compared to the catheters which are tapered over the entire length. I can
also tell you that the fluid travelling through the center lumen is a
phospholipid powder dissolved in saline and the catheter is extruded from
Nylon-12 and is irradiated afterwards.

Does anyone have some experience or knowledge they could share or direct me
to a source where I might be able to find a solution to my problem. Your
help is greatly appreciated.

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