The RCA group CRRT were performed with Prisma flex or (Baxter Healthcare/Gambro Spain) or Informed machine with citrate pump. The function mode was continuous venovenous hemodiafiltration (CVVHDF) in postdilution mode with ST 150 filter sets. The substitution fluid was Accusol or Prismocal B22 .The dose of dialysis was 20-25 ml/kg/hr with blood flow 150-200 ml/min. Trisodium citrate solution (4%,136mmol/L) was infused into the arterial line prior to the blood pump at a dose of 4 mmol/L of plasma flow. Calcium chloride (5% 340 mmol/L elemental calcium) was infused into the venous return to maintain systemic ionized calcium in the normal range (0.99-1.30 mmol/L) and the targets values for ionized calcium (iCa2+) after the dialysis membrane were 0.25-0.35 mmol/L. The rale of calcium infusion was adjusted in a timely manner based on repeated measurements of calcium concentration

The heparin- free group The circuit was periodically flushed with 50 ml saline via access limb every 30 minutes .When pre-filter pressure started to rise, additional saline flushes would be given.

The investigators collected patient's plasma at study start (day 0) and at day 3, 5, 7, 14, 28) .Samples were used to measure inflammatory markers (Il 6, IL 8, IL 10 and TNFα) .

. Markers of dialysis efficiency (BUN, creatinine) and other parameters related to AKI (acid base status, calcium, phosphorus, hemoglobin). The recorded variables also included adverse events, dialysis clotting, hemodynamic status, duration of mechanical ventilation, inotropic support. The hemodynamic parameters were monitored by EV 1000 clinical platform .The investigators measured cardiac performance data, which includes cardiac output (CO), cardiac index (CI), stroke volume (SV), and stroke volume indexes (SVI). Moreover, it also provides information about systemic vascular resistance (SVR). Thus, patient hemodynamic parameters as mentioned above were measured at the following 6 time-point: after the initiation of CRRT (T1), every 6 hours later for 24 hours (T2, T3, T4, T5), and at hour-72 (T6).

cm3/min

L/min/m2

mmHg⋅min⋅mL-1

dynes · sec/cm5/m2

Hours of filter use

Unit/ml