RCA and CRRT

Q: Describe few conditions where Regional Citrate Anticoagulation (RCA) should be used with high caution during Continuous Renal Replacement Therapy (CRRT)?

Answer:

RCA is commonly used with CRRT to avoid clotting of filters but there are few situations where RCA should be either on hold or use with caution.

• Liver insufficiency particularly when transaminases  >1000 IU/L. Patients with such level of insufficiency can not metabolize citrate appropriately, causing severe acidosis.
• Severe cardiogenic shock when blood lactate values >8 mmol/L. These patients also can not metabolize citrate adequately.
• Any worsening metabolic acidosis with increasing anion gap 
• Decreasing ionized calcium requiring escalating calcium infusion rates 
• Increasing total calcium 
• A ratio of total calcium to ionized calcium >2.5

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References:

1. Apsner R, Schwarzenhofer M, Derfler K, et al. Impairment of citrate metabolism in acute hepatic failure. Wien Klin Wochenschr 1997; 109:123. 

2. Kramer L, Bauer E, Joukhadar C, et al. Citrate pharmacokinetics and metabolism in cirrhotic and noncirrhotic critically ill patients. Crit Care Med 2003; 31:2450. 

3. Meier-Kriesche HU, Gitomer J, Finkel K, DuBose T. Increased total to ionized calcium ratio during continuous venovenous hemodialysis with regional citrate anticoagulation. Crit Care Med 2001; 29:748. 

4. Bakker AJ, Boerma EC, Keidel H, et al. Detection of citrate overdose in critically ill patients on citrate-anticoagulated venovenous haemofiltration: use of ionised and total/ionised calcium. Clin Chem Lab Med 2006; 44:962.