Continuous Renal Replacement Therapy

This prospective observational study will evaluate changes in intra-abdominal pressure in critically ill adult patients receiving continuous renal replacement therapy in the intensive care unit. Intra-abdominal pressure will be measured through the urinary bladder at predefined time points during therapy. The study will also assess the relationship between intra-abdominal pressure changes and clinical variables, including fluid balance, hemodynamic parameters, vasopressor requirement, urine output, severity scores, duration of renal replacement therapy, intensive care unit and hospital length of stay, and 30-day survival. No additional treatment or therapeutic intervention will be administered for research purposes.

In patients requiring renal replacement therapy (RRT) in the intensive care unit (ICU), continuous techniques are predominantly using due to better hemodynamic tolerance. The most employed techniques in ICU are continuous venovenous hemodiafiltration (CVVHDF) and continuous venovenous hemodialysis (CVVHD). To our knowledge, there are no prospective studies comparing the efficiency of these two techniques with the same dose of dialysis (and the same filter). In the CompEER study, we aim to compare the efficiency of CVVHD and CVVHDF on urea reduction rate in intensive care patients with acute kidney injury. The research hypothesis is that CVVHD citrate technique is as effective as CVVHDF heparin technique for urea reduction and provides prolonged and stable clearance, facilitating antibiotic management during RRT.

Filter clotting is a major complication of continuous renal replacement therapy (CRRT), resulting in blood loss, reduced treatment efficacy, and increased cost. One modifiable factor associated with filter clotting is filtration fraction (FF), or the proportion of plasma water being removed from the blood over the course of the filter. In convention, a cutoff of FF\<20-30% has been used to prevent hemofilter clotting, but no evidence correlating FF with hemofilter clotting has been documented. Some experts have proposed that post-filter hematocrit (Hct) could be a more direct marker for determining hemofilter clotting risk, but evidence supporting clinical utility of this marker is lacking. HCTpost=HCTpre/(FF(HCTpre-1)+1) In our proposed validation study, we hope to determine whether our formula for post-filter Hct provides accurate results when compared to measured values. The information obtained from this study will potentially justify the use of utilizing the formula in future studies. The procedure of this study is collecting blood samples from the post-filter lines of patients on CRRT at different time points and different flow rates. This will be considered the "measured post-filter hematocrit" which will then be compared to the calculated formula above, using the other values obtained from daily labs (for pre-filter hematocrit) and CRRT machine settings.

It is unclear whether different modes of continuous renal replacement therapy (CRRT) impact post-filter ionized calcium concentrations during regional citrate anticoagulation (RCA) when using calcium-containing replacement fluid. This prospective, single-center, observational cohort study will screen all patients receiving CRRT for eligibility. General clinical information will be collected before commencing CRRT treatment. Patients will be randomly assigned to either the veno-venous hemofiltration (CVVH) or continuous veno-venous hemodialysis (CVVHD) group and switch to the alternative mode in the subsequent treatment session. Pre-filter and post-filter ionized calcium, systemic total and ionized calcium, and effluent total and ionized calcium will be measured 2 hours after the initiation of CRRT. Electrolyte levels, arterial blood gases, hourly citrate dose, and total citrate dose will be recorded every 6 hours until the end of CRRT. The primary outcome is the difference in ionized calcium concentrations at each site over time between the two modes.

The only supportive therapy for patients with AKI is renal replacement therapy (RRT). In the ICU setting, continuous RRT (CRRT) is mostly favored. In a post-hoc analysis of the RICH trial (regional citrate versus systemic heparin anticoagulation for CRRT in critically ill patient with AKI), it was shown that the filter life span is associated with an increased rate of new infection and that the type of anticoagulants did not directly affect infection rate. The mechanisms of this infection rate is unknown.