CVAD maintenance of lumen integrity

Section Recommendation statement Grading of recommendations
30. How frequently a CVAD lumen should be flushed to maintain lumen patency remains unclear. It is suggested that a CVAD lumen that is used intermittently should be flushed no more frequently than every eight hours.  Consensus
31. The recommended solution for flushing a CVAD lumen is 0.9% saline (1-5). Grade B
32. To reduce the risk of thrombosis and intraluminal occlusion in large bore catheter lumens (e.g. dialysis catheters), an anticoagulant lock may be used when the lumen is not in use (2, 3, 6). Consensus
33. Unused lumens are to be managed to prevent air emboli and backflow of blood, protein or lipid solutions depending on the connector used. (Refer to Table 4 on 'Adjuncts to IV administration sets'. Consensus
34. It is recommended that syringes with a capacity of ≥ 10mL be used to access a CVAD for flushing. Smaller syringes exert higher pressure and may cause possible catheter rupture or dislodged an occlusion if excessive force is used. Consensus
35. When flushing a CVAD lumen use a pulsatile positive pressure flushing technique to create turbulence within the device lumen. Grade B
36. If attempting to flush a CVAD lumen due to a blockage, force should never be used because of the risk of catheter rupture. Consensus
37. Use of a solution other than 0.9% saline to unblock a CVAD lumen has been shown to be effective in restoring lumen patency. Use of agents such as urokinase and alteplase require a medical prescription and must be discussed with the Medical Officer or a Vascular Access specialist/team before use (7, 8). Grade B
The evidence review for these recommendations was current to December 2012. Clinicians are advised to check the literature as research may have been published that change these recommendations.

The evidence for maintaining catheter patency and reducing thrombotic risk indicates that 0.9% saline is equivalent to heparin solutions and safer in the context of risk associated with administration of heparin (1, 3) including bleeding complications. One study comparing 100 iU/kg continuous heparin infusion with 50mL of 0.9% saline/day showed the intervention group had a lower rate of infections (9). In a prospective randomised trial of heparin and saline flushed through a PICC using positive pressure Luer activated devices, there was no significant difference in occlusion rates, but there were occlusions reported in the saline group that had a significant cost implication for PICC replacement (2). More recently, studies have compared citrate as a lock solution not only for maintaining catheter patency but also to reduce the risk of infection (4, 10). Citrate is a safer option than heparin, but its availability in Australia is limited. At this time the pragmatic approach of instilling low concentrations of heparin (50 iU/mL or lower doses) or citrate-locking solutions may be considered for locking unused lumen in large bore catheters. Using a pulsatile flushing technique no more frequently than every eight hours and locking the unused lumens of the catheter, no more than twice weekly, was considered acceptable.

Grading of recommendations

Grade of recommendation Description
A Body of evidence can be trusted to guide evidence
B Body of evidence can be trusted to guide practice in most situations
C Body of evidence provides some support for recommendation/s but care should be taken in its application
D Body of evidence is weak and recommendation must be applied with caution
Consensus Consensus was set as a median of ≥ 7
Grades A–D are based on NHMRC grades (11)


  1. Schallom ME, Prentice D, Sona C, Micek ST, Skrupky LP. Heparin or 0.9% sodium chloride to maintain central venous catheter patency: a randomized trial. Critical Care Medicine. 2012;40(6):1820-6. PubMed PMID: 22488006.
  2. Bowers L, Speroni KG, Jones L, Atherton M. Comparison of occlusion rates by flushing solutions for peripherally inserted central catheters with positive pressure Luer-activated devices. Journal of Infusion Nursing. 2008;31(1):22-7. PubMed PMID: 18202556.
  3. de Neef M, Heijboer H, van Woensel JBM, de Haan RJ. The efficacy of heparinization in prolonging patency of arterial and central venous catheters in children: a randomized double-blind trial. Pediatric Hematology & Oncology. 2002;19(8):553-60. PubMed PMID: 12487830.
  4. Hermite L, Quenot J-P, Nadji A, Barbar SD, Charles P-E, Hamet M, et al. Sodium citrate versus saline catheter locks for non-tunneled hemodialysis central venous catheters in critically ill adults: a randomized controlled trial. Intensive Care Medicine. 2012;38(2):279-85. PubMed PMID: 22124771.
  5. Rabe C, Gramann T, Sons X, Berna M, Gonzalez-Carmona MA, Klehr H-U, et al. Keeping central venous lines open: a prospective comparison of heparin, vitamin C and sodium chloride sealing solutions in medical patients. Intensive Care Medicine. 2002;28(8):1172-6. PubMed PMID: 12185445.
  6. Hall KFM, Bennetts TM, Whitta RKS, Welman L, Rawlins P. Effect of heparin in arterial line flushing solutions on platelet count: a randomised double-blind study. Critical Care & Resuscitation. 2006;8(4):294-6. PubMed PMID: 17227264.
  7. Gabrail N, Sandler E, Charu V, Anas N, Lim E, Blaney M, et al. TROPICS 1: a phase III, randomized, double-blind, placebo-controlled study of tenecteplase for restoration of function in dysfunctional central venous catheters. Journal of Vascular & Interventional Radiology. 2010;21(12):1852-8. PubMed PMID: 21111365.
  8. Haire WD, Deitcher SR, Mullane KM, Jaff MR, Firszt CM, Schulz GA, et al. Recombinant urokinase for restoration of patency in occluded central venous access devices. A double-blind, placebo-controlled trial. Thrombosis & Haemostasis. 2004;92(3):575-82. PubMed PMID: 15351854.
  9. Abdelkefi A, Torjman L, Ladeb S, Othman TB, Achour W, Lakhal A, et al. Randomized trial of prevention of catheter-related bloodstream infection by continuous infusion of low-dose unfractionated heparin in patients with hematologic and oncologic disease. Journal of Clinical Oncology. 2005;23(31):7864-70. PubMed PMID: 16258088.
  10. Power A, Duncan N, Singh SK, Brown W, Dalby E, Edwards C, et al. Sodium citrate versus heparin catheter locks for cuffed central venous catheters: a single-center randomized controlled trial. American Journal of Kidney Diseases. 2009;53(6):1034-41. PubMed PMID: 19394731.
  11. Hillier S, Grimmer-Somers K, Merlin T, Middleton P, Salisbury J, Tooher R, et al. FORM: an Australian method for formulating and grading recommendations in evidence-based clinical guidelines. BMC Medical Research Methodology. 2011;11:23. PubMed PMID: 21356039.


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