Forum topic

In our facility we flush 2x daily with 10ml-20ml NS.  When the floor RN's are diligent with this and flushing after each use, we don't see any increase in the occlusion rate.  What we have found is that when line care is not being preformed according to policy we are seeing these lines occlude more often.  My reasoning for this would be that it is easier to have a total occlusion of the smaller lumen.

I do not recall seeing any data comparing rates of lumen occlusion based on the size of the lumen. But physics show that a smaller lumen will have blood reflux for a greater distance than a larger lumen. This would mean that a greater length of catheter could be occluded with a smaller lumen. Something is causing this blood to reflux and it is not the catheter design. I would work to reduce this by looking at flushing techniques and the specific brand and type of needleless connector in use. The clamping sequence must be correct for the function of the needleless connector. Negative displacement - flush, lock, clamp, then disconnect syringe. Positive displacement - flush, lock, disconnect syringe, then clamp. Neutral - clamping sequence does not matter.

Disconnection and flusing and locking must occur as soon as the fluid is infused. There are now 2 NCs that will automatically close when the fluid runs down into the tubing - TKO from Nexus Medical and Neutron from ICU Medical. All the others remain an open conduit for blood to reflux and clot before the set is disconnected.

Another factor is the design of the syringe. Are you using prefilled syringes or is pharmacy or nursing filling traditional syringes? If using prefilled, is your brand one of several designed to prevent syringe-induced reflux? When all fluid is flushed out of the syringe, the rubber gasket on the plunger rod is compressed. Releasing this pressure is required to disconnect the sryinge from the NC. This causes the gasket to expand and draw blood back into the catheter lumen. Even if you are using heparin lock, there would be thrombotic occlusion with a traditional syringe because the blood and heparin are not mixing in the lumen. If using a traditional syringe, leave a small amount of fluid in the syringe to prevent compression of the gasket.

Catheter occlusion can also be caused by what is happening inside the vein around the catheter tip - fibrin sheath, vein thrombosis at the tip. Where is the exact tip location of these PICCs?

Then there could be occlusion from drug precipitate, lipid accummulation from IVFE, and other mechanical issues such as muscle contraction if the patient is doing heavy lifting with these PICCs. Muscle contraction in the arm is one major factor that moves blood back to the heart. Arm muscles contract compressing the vein and could also compress the catheter forcing the lock solution out of the catheter and allowing blood to reflux into the lumen.

Finally, the evidence supporting the use of normal saline for locking any CVAD is simply not sufficient. There are several studies showing that heparin is better than saline, but we still need more evidence on this issue. The INS standards stated that saline is sufficient for locking a peripheral catheter but not for a CVAD and recommended that heparin be used, 10 units per mL. References can be found in the INS Standards document.

Lynn