On April 15 the Infusion Nurse's Society (INS) sponsored an on-line Webinar entitled "Current Guidelines for Flushing Vascular Access Devices."  This was a live presentation by Lynn Hadaway M.Ed., RN, BC, CRNI.  Lynn is a well known expert in infusion related topics and has an informative website www.hadawayassociates.com.  The Webinar was accessed via personal computer and slides could be viewed while Lynn lectured.  E-mailed questions were addressed following the presentation.  What a great way to to attend an informative seminar from your home or office!  

Lynn identified three patency problems seen with vascular access devices.  The first is thrombus or clot material that forms near, within, or around the catheter tip and lumen.  Diagnosis for this is sometimes difficult, and requires contrast injection and fluoroscopy.  Negative displacement needleless devices and compression of the rubber plunger gasket at the completion of flush can contribute to reflux of blood into the lumen increasing risk of thrombus formation.

In addition, excessive coughing, vomiting and heaving, straining, or heavy lifting can cause blood reflux.  Reflux can be reduced by use of a neutral needleless end adapter, or postive pressure flushing technique.  This is achieved by maintaining pressure on the plunger near the end of flush, clamping the device, then removing the syringe.  Leaving a small amount of fluid in the syringe helps to prevent compression of the rubber plunger gasket into the empty syringe.

The second  patency problem identified is drug or lipid precipitate formation.  It is very important to notify your infusion pharmacy to check compatibilities of prescribed intravenous medications and TPN solution.  Very few drugs can be given simultaneously with TPN.  Flushing with 10 ml of sodium chloride between IV medications can help reduce or prevent precipitate.  Alcohol flush has been sucessfully used to clear suspected lipid precipitate.

Mechnical causes can affect patency also.  These can include kinking, tight sutures, pinch-off syndrome, ballooning, and malpositioned central venous catheters and ports.  Each of these problems needs to be assessed and treated individually depending upon the circumstances.

Unfortunaltely there is a lack of solid research supporting flushing practices to prevent or decrease patency complications.  We do know that flushing is necessary at the completion of infusions, between and after IV medication administration, and after blood sampling.  Sodium chloride is used to flush out medication, blood, or infusion solution residue from catheters.  It can be used alone in valved devices or with approved needleless end adapters.  Heparin flush is used as a lock to prevent clot formation in the catheter tip.  Heparin is available in 10 Unit to 100 Unit concentrations and is usually given in 3-5 ml amounts depending upon the type of catheter used.  Several concerns to consider with heparin usage are drug incompatibilities, recent recalls of contaminated heparin vials and syringes, and heparin induced thrombocytopenia.  Multiple dose vials for sodium chloride and heparin flushing should be avoided because of their potential for bacterial contamination.

Any of the above three complications will cause resistance when flushing is attempted.  Excessive pressure and force may cause catheter ballooning or rupture.  A 10 ml syringe should be used for flushing because it generates the least amount of pressure on the catheter wall.  Smaller syringes produce a greater flushing force and should be used cautiously.