Particulate catheter occlusion

PN solutions should be administered with an infusion pump to ensure consistent and controlled delivery of the solution. The intravenous administration line may include an in-line filter at a point prior to connection to the catheter. A 0.22-micron filter is recommended for use with CAA-dextrose solutions to remove particulate matter, air, and any microorganisms that may be present in the solution from prior manipulations of the admixture or the administration line. Because the average size of IVLE particles is approximately 0.5 micron, IVLEs administered separately from the CAA-dextrose solution must be piggybacked into the PN line at a site beyond the in-line fllter. Routine use of in-line filters (>0.22 micron) with TNA solutions is controversial. However, the FDA recommends use of a 1.2-micron filter, which may be effective in preventing catheter occlusion due to precipitates or lipid aggregates. This filter size is also reported to remove Candida albicans. 

Coils are available in a wide variety of sizes from 2 mm to 15 mm in size and are made from either stainless steel or platinum and may have Dacron fibers placed at right angles to the long axis of the coil to increase the surface area and thereby to increase the speed and permanence of thrombosis. In practice, most coils utilized in microcatheters are platinum and those in 4- to 5-F catheters, stainless steel. It should be noted that all coils are permanent devices and should be utilized when the desired occlusion is permanent. Coils should not be used in combination with particulate embolization for the treatment of tumors, as they will occlude the access for further treatment. Coils may, on the other hand, be utilized with Gelfoam embolization in the treatment of pelvic bleedings allowing the hemorrhage to be halted quickly and permanently. 

Embolization involves the deliberate occlusion of the arterial supply to the tumor to create ischemia, tumor necrosis, and to arrest growth by the intraarterial delivery of particulate materials, sclerosing solutions and substances introduced in a liquid state that eventually solidify or precipitate. This concept was first described in 1960 by Dawbain et al, who injected melted paraffin-petrolatum into an external carotid artery in a patient with head and neck cancer. It wasn t until the early 1970s that catheter technology improved to the degree for transcatheter embolotherapy to emerge. 

The stomach and duodenum have a rich collateral blood supply and hence embolization of branches of the coeliac axis can be performed with a low risk of infarction of the viscera. Conversely, the extensive vascular supply may make embolization more difficult to achieve. Thus, in addition to coils, a small particulate embolic agent is often required for a more distal block. A co-axial catheter system is likely to be necessary for this. The method of embolization depends on the angiographic findings but occlusion of the artery needs to be performed on either side of the abnormality (eroded artery or aneurysm) to achieve haemostasis. Ischaemia may be provoked... 

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