Catheter Port Reversal in Citrate Continuous Veno-Venous Hemofiltration

Introduction: Knowledge of effects of catheter port reversal (CathPR), when blood is withdrawn from the venous port and returned via the arterial port, often used in dysfunctional catheters in renal replacement therapy, is limited in the setting of citrate continuous veno-venous hemofiltration (CVVH). Methods: In this open trial, post-filter ionized calcium (PfiCa), post-filter citrate concentration (PfCC), catheter recirculation, and solute clearance were measured before, during, and after 6 hours of CathPR, in well-functioning catheters. All other settings, including citrate settings, were left constant during the study. Results: Twenty-three patients were included. Mean PfiCa before CathPR of 0.36 mmol/L (SD 0.06) decreased to 0.31 (0.04) after 2 hours (P = 0.002), 0.31 (0.04) (P = 0.002) at 4 hours, and 0.31 (0.04) at 6 hours (P = 0.001). Return to normal increased mean PfiCa to 0.34 (0.06) (P = 0.006). Mean PfCC rose from 592 mg/L (SD 164) before CathPR to 649 mg/L (190) after 2 hours (P = 0.045), to 696 mg/L (192) after 4 hours (P < 0.001), and to 657 mg/L (214) after 6 hours (P = 0.018). Return to normal decreased mean PfCC to 598 mg/L (184) (P = 0.024). Mean recirculation increased during CathPR (from 4.3% [0-8.7] before to 13.8% [9.7-22.2], P < 0.001). Urea, potassium, and creatinine clearances dropped significantly, but calcium clearance was unaffected. Conclusion: CathPR caused a significant decrease in PfiCA and increase in PfCC. Calcium handling differs from other solutes because of increases caused in citrate concentration and subsequent effects on calcium chelation. In citrate CVVH, CathPR in dysfunctional catheters should be limited in time, with intensive follow-up.