For the first time, this document includes a definition of “blood return” in the glossary, stating this is a component of VAD patency assessment and that the blood should be the color and consistency of whole blood. Blood return from peripheral catheters is included in standards on documentation, flushing and locking, VAD assessment, VAD removal, infiltration and extravasation, and antineoplastic agents.
Many old nursing references state that reliance on blood return is not adequate to determine if the catheter is infiltrating fluid. The nurse can not rely exclusively on the presence of absence of a blood return before using the peripheral catheter. There could easily be a second puncture in the posterior vein wall and still get a blood return OR there could be a small catheter occluded by aspiration technique. For these reasons, the assessment must also include observing the appearance of the site, including comparison to the opposite extremity; palpating for change in temperature or induration; and patient complaints about the site.
Other reasons for a lack of blood return could be damage to the endothelial vein lining producing edema or small thrombi that occlude the back flow of blood. Fluid may not be escaping from the vein – yet. But this damage can lead to infiltration or extravasation and continued use will only exacerbate the current complication. Complications are seen more frequently when venous sites in the hand, wrist, and antecubital fossa are used.
The 2016 Standards now call for obtaining a blood sample from a peripheral catheter during the dwell time instead of during the insertion procedure. Studies are showing that this is a successful practice. If the peripheral catheter will yield a blood sample, it can easily produce a blood return for patency assessment.
As I mentioned, technique can be the cause of failure to obtain a blood return. First and foremost, use a slow and gentle technique to aspirate from the catheter. Pulling hard and fast on the syringe plunger can pull the vein wall over the catheter lumen. Next, change to a smaller syringe as aspiration with a smaller syringe produces less pressure and better results. That is opposite from what happens with injection where a larger syringe is recommended. Finally, put a tourniquet on the arm above the catheter tip to see if there is a blood return. If all of these techniques fail to produce a blood return, do NOT use the catheter.