Is Regional Citrate Anticoagulation With Fixed Citrate Blood Concentration More Effective and Easy-to-handle Than Adjusted-dose Protocol in Adult Critically Ill Patients? A Cohort Study

Design: This study was conducted as a single-centre, cohort study. All patients older than 18 years of age who required veno-venous hemofiltration (CVVH) were consecutively screened forward (prospective) or backward (retrospective) from August, 2015 and until the expected sample size was reached.

Study protocol: Before and after implementation of a new protocol, apart from the flow rate of any supplementation (Anticoagulant-citrate-dextrose solution, 5% sodium bicarbonate injection and 10% calcium gluconate injection), CVVH was performed using same standards, including devices (Aquarius or Diapact® CRRT), venous catheter (a double lumen 12-F catheter, Arrow International Inc., USA), haemofilter (DIACAP Acute L, 2.0 m2, B. Braun Melsungen AG, Germany), commercial replacement fluids (Na+113, Cl-118, Mg++0.797, Ca++1.60, glucose 10.6mmo/l and zero bicarbonate; Qing-shan-li-kang pharmaceutical Co.,Ltd. Cheng-du, China) and Anticoagulant-citrate-dextrose solution-A (ACD-A) (Na+ 224, citrate 113, bicarbonate 203mmol/l, Fresenius Kabi, Italy) as well as monitoring algorithm. The first sample of postfilter and systemic ionized calcium was done two hours after initiation of CVVH and every six to eight hours during the first 24 hours. Afterwards, these measurements were done according to clinical needs for maintaining normal ionized calcium levels and blood pH value.

The group of fixed citrate concentration: ACD-A was administered in the prefilter ahead of the blood pump and the infusion rate was fixed and set to meet a circuit citrate concentration of 4 mmol/l. Calcium Gluconate 10% Injection was infused through the return line of the circuit and the substitution flow was initiated with 0.8 mmol calcium per liter total effluent flow and then be adjusted to obtain systemic ionized calcium levels between 0.90 and 1.2 mmol/l. Sodium bicarbonate 5% injection was infused through the return line of the circuit and the substitution flow was initiated with 3.3% of replacement fluid flow and then be adjusted to obtain blood pH value in the normal range (7.35 to 7.45)

The group of adjusted citrate doses:ACD-A was administered in the prefilter ahead of the blood pump and the starting infusion rate was 2.5 % of blood flow and then be adjusted to obtain postfilter ionized calcium levels of less than 0.40 mmol/l. Calcium Gluconate 10% Injection was infused through the return line of the circuit and the substitution flow was initiated with 7.3% of ACD-A flow, and then be adjusted to obtain systemic ionized calcium levels between 0.90 and 1.2 mmol/l. Sodium bicarbonate 5% injection was infused through the return line of the circuit and the starting infusion rate was 4% of replacement fluid flow,and then be adjusted to obtain blood pH value in the normal range (7.35 to 7.45)

Statistical analyses: groups were compared by using Fisher's exact test, Student's t test or Mann-Whitney rank-sum test as appropriate. Circuit lifetime was evaluated with Kaplan-Meier survival analysis and survival curves distribution was compared with the Log Rank test. Univariate and multivariate analysis were used to identify factors associated with mean filter lifetime in all group patients.