Is antimicrobial citrate lock therapy routinely used, and what precise standing order should I provide to the dialysis unit for catheter lock solution?

Antimicrobial Citrate Lock Therapy for Hemodialysis Catheters

Low-concentration citrate (<5%) is a reasonable and increasingly common catheter lock solution that you should consider using, particularly for preventing catheter-related bloodstream infections (CRBSI), though the choice between citrate and heparin remains at clinician discretion according to current guidelines. 1

Is Antimicrobial Citrate Lock Common Practice?

Antimicrobial citrate lock solutions are becoming more widely adopted in dialysis units, though practice varies significantly between facilities. 2, 3

• KDOQI 2019 guidelines state that the choice between citrate or heparin as a CVC locking solution is based on clinician discretion, as there is inadequate evidence to demonstrate a difference in CVC survival or complications between these solutions. 1

• However, KDOQI specifically suggests using low-concentration citrate (<5%) to help prevent CRBSI and catheter dysfunction when feasible. 1

• Evidence shows citrate lock solutions reduce CRBSI rates compared to heparin (0.28 vs 0.91 episodes per 1,000 catheter-days when combined with gentamicin), while maintaining similar catheter patency. 4

• Citrate offers several clinical advantages: eliminates heparin-associated bleeding complications, improves reliability of INR assays, and provides an effective alternative for patients with heparin-induced thrombocytopenia. 3

Exact Standing Order for Dialysis Unit

Standard Citrate Lock Protocol:

Concentration and Volume:

• Use 4% sodium citrate or 5% trisodium citrate as the locking solution 2, 3, 5
• Instill volume per lumen according to catheter manufacturer specifications (typically matching the internal catheter volume) 1

At Dialysis Disconnection (Post-Treatment):

1. Flush the catheter: After retransfusing patient's blood, close clamps on CVC lumens and bloodlines, then disconnect one bloodline from one CVC lumen 1

2. Saline flush: Attach a 5-10 mL syringe with 0.9% normal saline to CVC lumen, unclamp CVC, and flush lumen using turbulent flushing technique 1

3. Instill citrate lock: Remove normal saline syringe, attach syringe with citrate locking solution, and instill the prescribed volume per unit CVC care protocols 1

4. Secure the catheter: Close clamp on lumen, remove syringe, clean the hub using "scrub-the-hub" protocol with chlorhexidine, and apply sterile Luer lock cap 1

5. Repeat for second lumen 1

At Dialysis Connection (Pre-Treatment):

1. Ensure clamps closed: Remove Luer lock cap and clean the hub with chlorhexidine 1

2. Aspirate lock solution: Attach syringe, unclamp CVC, and aspirate 2-5 mL of blood and citrate locking solution from lumen, then reclamp 1

3. Optional saline flush: If no resistance felt with aspiration, attach 5-10 mL syringe of 0.9% normal saline and flush lumen using turbulent flushing technique 1

4. Connect to dialysis circuit and repeat with second port 1

Sample Standing Order Language:

"For all tunneled hemodialysis catheters: Use 4% sodium citrate lock solution at end of each dialysis session. Instill volume per catheter manufacturer specifications (typically 1.5-2 mL per lumen). Follow standard aseptic technique with hub disinfection using chlorhexidine. Aspirate and discard lock solution before initiating next dialysis treatment." 1, 3

Important Clinical Considerations

Antimicrobial lock solutions (including citrate) probably reduce CRBSI per 1,000 catheter-days (RR 0.38,95% CI 0.27-0.53), though evidence certainty is low. 6

• Non-antibiotic antimicrobial lock solutions like citrate reduce CRBSI for tunneled CVCs specifically (RR 0.60,95% CI 0.40-0.91) but show less benefit for non-tunneled catheters. 6

• Citrate and heparin demonstrate comparable catheter dysfunction rates (1.11 vs 1.73 per 1,000 catheter-days, not statistically significant). 5

• Cost savings with citrate are substantial—approximately 85% reduction in locking therapy costs compared to concentrated heparin. 3

Common Pitfall: Do not exceed the internal catheter volume when instilling lock solution, as systemic spillage can cause complications. 2 Always verify catheter-specific fill volumes from manufacturer specifications.

Additional measure for high-risk patients: Consider antimicrobial barrier caps to further reduce CRBSI in high-risk patients or facilities with elevated infection rates. 1, 7