Occlusion may result from fibrin sheath formation, catheter thrombosis, medication precipitate or external compression.


  • Check for incompatible medications prior to simultaneous or sequential infusion of two or more medications
  • Flush the line with a compatible IV solution between medication infusions
  • Always use positive pressure when “locking up” the catheter to prevent reflux of blood into the catheter tip


  • Assess for catheter patency by withdrawing 2.5mL of blood into a 10mL syringe. Discard

If blood does not return:

  • Have the patient change positions, raise arms and/or cough repeatedly in order to shift the position of the catheter from the vein wall
  • Attempt a “pull-push” Manoeuvre using a normal saline-filled syringe, 20-30mL (avoid using force or high pressure)
  • If the infusion continues to be impeded after performing the above, a fluoroscopy should be ordered to determine the presence of a fibrin sheath.  Always suspect a fibrin sheath if fluid flows in easily but blood return is impaired
  • Fibrin or blood clots may be dissolved using Urokinase or TPA which converts plasminogen to plasmin and acts directly on the clot.  Urokinase ([500 IU/mL]) is instilled into the catheter.  The amount is calculated according to the internal diameter or the total volume of the catheter.  After instillation the drug is allowed to act for 5 minutes. After 5 minutes, an attempt to aspirate is made every 5 minutes for 30 minutes.  After 30 minutes the device is clamped and another attempt may be made in 30 minutes.  If this is unsuccessful then a second instillation is done.
  • If the occlusion is caused by a precipitate then other agents can be used to alter the pH.