The fluctuation of circuit pressure parameters may reflect the severity of circuit clotting, but it is unclear yet which one has the highest precision for the prediction of filter clotting. Increased filter pressure drop (FPD) and transmembrane pressure (TMP) are associated with filter coagulation during continuous renal replacement therapy (CRRT). They are affected by blood flow velocity and ultrafiltration rate, which can lead to false coagulation alarms. To eliminate these effects, we proposed two parameters: blood flow resistance (BFR) and transmembrane flow Resistance (TFR), and explored their role in predicting filter clotting. We conducted a retrospective analysis of patients who underwent CRRT at Jinling Hospital between March and June 2025, and experienced at least one filter change due to clotting during CRRT. CRRT modes included continuous veno-venous hemofiltration (CVVH) and hemodialysis (CVVHD). The records of continuously monitored circuit pressure parameters were extracted. The calculated parameters, including filter pressure drop (FPD), blood flow rate-adjusted FPD(blood flow resistance, BFR), transmembrane pressure (TMP), and ultrafiltration rate-adjusted TMP(transmembrane flow resistance, TFR), were further analyzed for the association of their changes with filter clotting. To verify the necessity of adjusting FPD by blood flow rate and TMP by ultrafiltration rate, a prospective study was conducted to investigate the effect of variations in blood flow rate and ultrafiltration rate on 4 pressure parameters by intentionally stepwise modulating flow rate during the start period of the CRRT session. A total of 96 CRRT circuits (76 CVVHD and 20 CVVH) from 51 patients were included. In CVVHD mode, the efficacy of ΔBFR and ΔFPD was significantly higher than that of ΔTFR and ΔTMP (all p 0.05). A Combination of ΔBFR and ΔTFR by the parallel rule (positive if ΔBFR > 0.075 mmHg/(ml/min) or ΔTFR > 0.115 mmHg/(ml/h)) had yielded a sensitivity of 77.1% and a specificity of 62.9% for the prediction of 1-hour later filter clotting irrespective of CRRT mode. The prospective part of the study showed that FPD was blood flow rate-dependent but not BFR, and TMP was ultrafiltration rate-dependent but not TFR. BFR (Blood flow rate-adjusted FPD) and TFR (ultrafiltration rate-adjusted TMP) are potential predictors of filter clotting, warranting further studies to verify their value.
Hu et al. (Tue,) studied this question.