I V infiltration: Not just a peripheral problem

Nursing, Sep 1999 by Hadaway, Lynn C

Checking catheter patency

A traditional way to assess catheter function is to attach a syringe and slowly draw back to obtain a blood return. You should obtain a blood return before giving any medication-- especially a vesicant. First, gently flush the catheter with 0.9% sodium chloride solution and check for any resistance to flushing, changes at the insertion site (such as edema or leaking), and patient complaints of discomfort. If you encounter no problems gently aspirate for blood.

Keep in mind, however, that this method can also be misleading. You can't assume that a free-flowing blood return rules out infiltration. You could obtain a free-flowing blood return even when infiltration is present under these circumstances:

the catheter tip has eroded through the vessel wall, yet the tip remains partially inside the lumen

blood flow is obstructed, forcing blood to flow out of the vein

the inflammatory process is occurring, causing endothelial cells to retract and fluid to leak.

Similarly, the absence of blood return doesn't necessarily confirm infiltration. A blood return is usually absent when:

fibrin occludes the catheter tip

the tip is pressed against the vein wall

you attempt to aspirate too aggressively (pulling back on the syringe plunger too quickly and forcefully can cause soft catheters, such as peripherally inserted central catheters, to temporarily collapse)

blood flow is impeded by a large catheter in a small vein.

Another way to check for patency of a gravity-flow peripheral I.V line is by using the tourniquet test. While the I.V. solution is infusing, place the tourniquet on the arm well above the site. Then observe the gravity drip of the fluid. If the drip rate isn't affected by venous constriction from the tourniquet, the test is positive for infiltration. If the infusion were running properly, the venous compression from the tourniquet would dramatically slow the drip rate. Keep in mind, however, that because obstruction of blood and fluid flow is a cause of infiltration, the tourniquet test could contribute to problems. If you use it, apply the tourniquet gently and for only a brief time.

Central-line considerations

When a central venous catheter doesn't yield a blood return, you may attempt to salvage the line by instilling a thrombolytic agent to dissolve fibrin inside the lumen or initiating a thrombolytic infusion to dissolve a fibrin sheath around the outside of the catheter. Or the physician may order a cathetergram to determine the fluid pathway through the catheter. Performed under fluoroscopy, the procedure involves injecting a dye through the catheter and watching to see if it flows into the vein or backflows along a fibrin sheath and out the insertion site.

If a fibrin sheath has formed outside the catheter and thrombolytic therapy won't clear the obstruction, an interventional radiologist may use a stripping procedure to pull the sheath off the catheter and preserve the line.

With a subclavian line another possible reason for obstruction of fluid flow is that the catheter is pinched between the clavicle and first rib, a situation that can lead to catheter fracture, emboli, and fluid escaping into the tissue from the fractured section.