Question: Is there a standard concentration of Heparin to use for flushes?

I know of 2 different facilities. One uses 10 u / ml and one uses 100 u / ml. In the Infusion Therapy Standards of Practice, it says “Lock CVADs with either heparin 10 units per mL or preservative-free 0.9 % sodium chloride (USP), according to the directions for use for the VAD and needleless connector.” (p. S78 / I) Our facility has been using the 100 u / ml and administering 5 ml for years. We want to know what the standard is. D.H. Pennsylvania 6/4/19


There is no standard for heparin. Recommendations and guidelines state there is insufficient evidence to support the use of heparin flushes. Research has demonstrated success with normal saline locking solutions. Why use heparin if it is not necessary and there are issues associated with HIT/contamination/compatibility?

Here is an excerpt from a book that will be published open access and become available within the next month (VHP, Moureau 2019):

Flushing and Locking Solutions – Heparin versus Saline

The use of heparinized solution to maintain CVAD function has been accepted practice for decades (Anderson 2010) despite the lack of definitive, high quality evidence to support its continued use (Lopez-Britz 2014, Hadaway 2006a). More emphasis is being placed on risk associated with heparin use from contamination issues or other disorders and newer guidelines are reflecting the change to saline only with elimination of heparin as a flushing agent for general use (Gorji 2015). Heparin can result in serious side effects (Lopez-Briz, 2014) such as heparin-induced thrombocytopenia (HIT), heparin induced thrombosis and thrombocytopenia syndrome (HITTS), allergic reaction, drug incompatibility and possible iatrogenic hemorrhage (Jonker, 2010). Despite heparin induced disorders being uncommon (Anderson, 2010), it has been estimated that they can develop in up to 30% of patients with the possibility of occurrence 40 days after the cessation of heparin (Gorji, 2015). Even small concentrations of heparin can induce HIT in susceptible patients (Musliamani, 2007), often with serious and life-threatening consequences (Anderson, 2010).    

Given potential safety concerns with the use of heparin, 0.9% sodium chloride may be the preferred flushing and locking solution for short term CVAD maintenance (RCN, 2016, Loveday, 2014, NICE, 2012). There is a growing body of evidence to suggest that flushing with 0.9% saline is equally as effective in preserving catheter patency (Pittiruti 2009, Mitchell 2009, Anderson 2010, Jonker 2010, Shallom 2012, Lopez-Britz 2014, NICE 2015, Gorji 2015, Hoffer 1999). Current guidelines recommend that short peripheral catheters be locked with preservative-free 0.9% sodium chloride following each catheter use in adults and children (Gorski et al, 2016). The ESPEN guidelines (2009) advocate sterile sodium chloride to flush and lock CVAD catheter lumens that are in frequent use for administration of parenteral nutrition (PN), warning that heparin may facilitate the precipitation of lipids within the catheter lumen (Pittiruti 2009).

The current evidence reported in the literature is of poor to moderate quality (Lopez-Briz 2014), however the most recent study by Gorji (2015) is a high quality double blind RCT with a moderate cohort of 84 patients who were randomly assigned to 2 groups, to receive either heparin saline (3ml) or 0.9% saline (10ml). Results are consistent with an earlier, similar trial by Shallom (2012) demonstrating that heparinized saline did not have a statistically significant effect on improved patency and survival of CVADs compared with 0.9% sodium chloride (Gorji 2015). More RCTs are needed to ensure National and International guidelines can be developed based on the best available scientific evidence (Anderson 2010) to help organizations ensure the best possible experience and outcomes for patients.    

A recent Cochrane Report (2014) comparing heparin with 0.9% saline flushes to prevent CVAD occlusion in adults analyzed six studies with a combined total of 1,433 participants. This systematic review found no compelling evidence to suggest that heparinized solutions were more effective than saline in reducing CVAD occlusion or associated complications such as thrombosis or infection (Lopez-Britz 2014). The implications for practice section of the review acknowledges that heparin flushing, and locking is currently a recommended practice in many guidelines and clinical settings. Lack of conclusive evidence combined with higher cost and potential side effects resulted in heparin not being recommended for use (Lopez-Briz 2014).  

NICE guidelines (2017) have developed this Cochrane Quality and Productivity topic and support its view that there is insufficient evidence to support heparin-based flushes. Recommendations are made to flush and lock CVADs catheter lumens with sterile 0.9% sodium chloride (NICE 2017). However, NICE guidelines also advise that when recommended by the manufacturer, implanted ports or open-ended catheter lumens should be flushed and locked with heparin sodium flush solutions (NICE, 2017).  

Guidelines such as EPIC 3 (Loveday 2014), ESPEN (Pittiruti 2009) and CDC HICPAC (O’Grady et al., 2011) also recommend using sterile normal saline for injection to flush and lock catheter lumens that are accessed frequently, stating that manufacturers may recommend heparin flushes for implanted ports or open-ended CVADs that are accessed infrequently. Adherence to manufacturer’s instructions is echoed in the guidelines published by NICE (2017), and the Infusion Standards of Practice (INS/Gorski et al, 2016). Flushing with a heparin solution is recommended potentially useful for CVADs that are infrequently accessed or for patients receiving home PN or for ports (Pittiruti, 2009).

I hope this information is helpful to you!

Warm wishes, Nancy

Nancy Moureau, PhD, RN, CRNI, CPUI, VA-BC

Chief Executive Officer – PICC Excellence, Inc, Hartwell, GA, USA

Vascular Access Specialist, Adjunct Associate Professor, Griffith University, Brisbane, Australia

Alliance for Vascular Access Teaching and Research (AVATAR) Group, Queensland, Griffith University, Brisbane, Australia

Office 706-377-3360

Cell 706-614-8021

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