Managing occlusions by negative pressure

How to break those blockages

By Nancy Moureau, BSN, CRNI

President, PICC Excellence

Orange Park, FL

Occlusion is a common complication with central venous catheters (CVCs). There currently is a diverse number of CVCs being used, including peripherally inserted central catheters (PICCs), non-tunneled subclavian devices, tunneled, Hickman, Broviac or Groshong chest lines, subcutaneous implanted ports, and dialysis catheters.

Management of these lines is based on the policy of the facility and the specific manufacturer's recommendations for that product. All medical professionals should be familiar with the product information specific to the CVC being used. Complications with CVCs, such as catheter occlusion, catheter breakage/fracture/emboli, resistance to removal, thrombosis, infection/sepsis, malpositioning/migration, phlebitis, hemorrhage, and air emboli can cause missed doses, increased cost with replacement, and patient risk. Therefore, for each of the above CVCs, home infusion professionals should have in-depth knowledge of techniques used to maintain devices administering intravenous therapies, particularly avoiding and troubleshooting occluded catheters.

Turbulent positive pressure flushing can help avoid sluggish or occluded catheters, with turbulence created by a pushing and pausing action on the plunger of the syringe which removes blood cells from the internal lumen of the catheter, thereby reducing the incidence of intraluminal clots. Positive pressure is used at the end of the flush by maintaining pressure while the clamp is engaged, thereby keeping blood from refluxing into the tip of the catheter.

Obstructions occur for a variety of reasons. Troubleshooting a supposed occlusion should consist of checking for mechanical obstruction within the tubing, pump, catheter, clamps, catheter insertion site, or sutures, as well as identifying the last medication infusion and the type of flushing that was used. Precipitates can be caused by many drugs and lipid solutions, and must be cleared by agents specific to that type of occlusion. Methods to clear non-thrombotic occlusions are 70% ethanol for lipid occlusions, 0.1N Hydrochloric Acid (HCl) for medication precipitates with low pH, or one mEq/ml sodium bicarbonate for high pH precipitates. Thrombotic occlusions can be cleared with urokinase using Abbokinase Open-Cath (Abbott Laboratories) 5000 IU/ml in 1ml and 1.8ml single-dose packages.

Heparin does not assist in clot lysis

Time is a factor in the success of catheter clearance. The longer a catheter remains occluded, the less chance for clearance. For example, urokinase is most effective for clots less than seven days old, while heparin is used within many facilities to reduce clotting with central lines. Urokinase is a naturally occurring enzyme, directly activating plasminogen to convert to plasmin, resulting in the lysis of a clot. The serum half-life of urokinase is approximately 20 minutes. Urokinase has been shown in studies to be 98.6% effective in restoring patency to catheters occluded by thrombotic occlusions. Heparin activates anti-thrombin III, which inhibits coagulation. But heparin does not assist in the lysis of formed clots, and only reduces their occurrence.

Concern exists over the pressure needed to instill the solutions when using catheter-clearing agents. A negative-pressure approach can be used, reducing the risk of catheter breakage. The negative-pressure technique can use a stopcock or simply a clamping catheter/extension and syringe.

To perform the negative-pressure procedure with a stopcock you will need two 10cc syringes, a sterile stopcock, urokinase or another agent, and normal saline and heparin for completion as applicable. The stopcock method for urokinase is as follows:

1. Assess the catheter and tubing for kinks, clamps, or other potential occlusions.

2. Supine positioning may be best (for PICCs have arm below the level of the heart).

3. Prepare the site by sterile central line dressing procedure. Include hub prep and secure the catheter.

4. Apply a sterile stopcock to the catheter hub, turned off to the catheter. Attach an empty 10cc syringe to stopcock.

5. Draw up a urokinase single dose into a 10cc syringe (approximately 1.0 ml or 1.8 ml) and attach to the other side of stopcock.

6. Turn stopcock off to urokinase.

7. Aspirate empty syringe back 8cc to 9cc and hold to create negative pressure in catheter. (If blood return is achieved, stop and flush per policy.)

8. Turn off stopcock to empty the syringe, allowing urokinase to flow into catheter.

9. Turn off the stopcock to patient.

10. Allow urokinase to remain in catheter per your policy, or for 30 to 60 minutes. Note: PICCs have a longer effective length than other central lines and may require urokinase to remain longer than average rates for port, Hickman, or Groshong catheters.

11. Repeat step seven at the allotted time. If blood return is achieved, draw off waste blood 3cc to 5cc and flush vigorously with saline 10cc to 20cc, then heparin per policy.

12. If no blood return, then continue through steps eight and nine, leaving urokinase in the catheter a longer period the second and third times. In cases where the line does not clear by the third check, urokinase can be left instilled in the catheter overnight, with aspiration in the morning. Secure catheter.

13. Avoid forceful or excessive aspiration of syringe.

14. Note: Clearance of lipid precipitate may require the use of ethyl alcohol. Certain medications may be cleared with sodium bicarbonate or dilute hydrochloric acid instead of urokinase. Urokinase works best on occlusions with blood clots.

For the negative-pressure approach without stopcock using the two-syringe method, proceed using the following steps:

1. Prepare site according to sterile central line dressing procedure. Include hub prep and secure the catheter.

2. Apply an empty sterile 10cc syringe to the catheter hub.

3. Draw up a urokinase single dose into another 10cc syringe (approximately 1.8cc).

4. Aspirate the empty syringe back 8cc to 9cc and hold to create negative pressure in the catheter. (If blood return is achieved, stop and flush per policy.) Clamp catheter or extension set.

5. Change syringes. Attach the syringe with urokinase. Unclamp the catheter, allowing the solution to flow into the catheter.

6. Reclamp the catheter.

7. Allow the solution to remain in the catheter per your agency's policy.

8. Repeat steps four through six at the allotted time. If blood return is achieved, draw off waste blood 3cc to 5cc, then attach the saline flushing with turbulent positive pressure 10cc to 20cc, then heparin, as applicable, per your policy.

9. Avoid forceful or excessive aspiration of syringe.

When an occlusion will not clear, or is due to precipitates, other solutions can be substituted for urokinase, which can also be used for extraluminal occlusions that prevent blood aspiration, as with a fibrin tail or sleeve. In this case the CVC can be flushed. You must know the intraluminal volume of the catheter to proceed with an instillation for aspiration occlusion. Once the volume of the catheter is known, instill the equal amount of urokinase, allowing it to remain 12 hours or overnight. Aspirate the CVC after the allotted time, and blood should be present. Draw off 3cc to 5cc of waste blood and flush per the policy.

Upon resolution of a complication, consideration should be given to the means of preventing future complications. Strategies may include changing the flushing technique or protocol, instituting heparin, using higher concentrations of heparin, increasing the frequency of flushing, or providing more thorough patient/nursing education. Solutions should be instituted after a problem has been identified. Complication reduction not only reduces the cost in the delivery of infusion therapy, but also the risk to the patient.

[Editor's note: Nancy Moureau, BSN, CRNI, is president of PICC Excellence Inc. PICC Excellence provides basic and advanced insertion training for PICCs and midlines across the country. PICC Excellence also provides a new training video for PICCs. For information on class locations, setting up your own class, or the video tape call (888) 714-1951 or (904) 264-9385.]

Related Readings

Lawson M, et al. The use of Urokinase to restore the patency of occluded central venous catheters. American Journal of Infusion Therapy 1982; 1:29-32.

Cunliffe M, Polomano R. How to clear catheter clots with Urokinase. Nursing 1986; 3:40-43.

Bjeletich J, Hickman R. Declotting central venous catheters with Urokinase in the home by nurse clinicians. NITA 1987; 17:428-430.

Bonstell R, Brown J. Declotting peripherally inserted central catheters with a new technique using Urokinase. JVAN 1992; 2:10-14.

Weiner ES, et al. The CCSG prospective study of venous access devices: an analysis of insertions and causes for removal. J Ped Surg 1992; 27:155-164.