ABSTRACT
Objective:To investigate the difference between the concentration of the peripheral ionized calcium (iCa) monitored at different blood collection points and the target concentration of anticoagulant efficacy in patients with continuous renal replacement therapy (CRRT), so as to provide scientific basis for the best blood collection point in clinical practice.Methods:Taking patients of department of critical care medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology receiving CRRT therapy with 4% citrate anticoagulation as research objects. Type of Prisma-FlexV8CRRT as well as department self-made substituate and dialyzate were adopted for all patients receiving CRRT therapy. Patients were divided into continuous veno- venous hemofiltration (CVVH) group ( n=10) and continuous veno- venous hemodialysis (CVVHD) group ( n=30) depending on their actual conditions and treatment needs. Blood collection was conducted at specific sites for extracorporeal peripheral ionized calcium concentration determination before and after the filter at the time of 2, 4, 8, 14, 20 hours following CRRT therapy for patients from both groups. Target concentration of extracorporeal peripheral ionized calcium was set as 0.2-0.4mmol/L for ensuring the efficacy of extracorporeal citrate anticoagulation. Results:Totally 400 testing results were obtained from 40 included patients during their treatment. In CVVH group, 100 testing results were obtained at the time of 2, 4, 8, 14, 20 hours following CRRT therapy and no significant statistical difference was shown ( P>0.05). In CVVHD group, 300 testing results were obtained at the time of 2, 4, 8, 14, 20 hours following CRRT therapy. The iCa concentration before the filter were (0.53±0.01), (0.50±0.01), (0.52±0.01), (0.53±0.01), (0.53±0.02) mmol/L while the iCa concentration after the filter were (0.41±0.01), (0.40±0.01), (0.39±0.02), (0.41±0.01), (0.40±0.01) mmol/L accordingly, and the difference was statistically significant ( t values were 75.24-103.41, P<0.01). Conclusions:For patients receiving CRRT treatment with citrate anticoagulation in different CRRT mode, testing results obtained from blood collection sites before and after the filter could not reflect the efficacy of citrate anticoagulation correctly and simultaneously to ensure the secure use of the extracorporeal pipelines and filter. In CVVH mode, iCa concentration determined from blood samples collected from sites before and after the filter could refelct the efficacy of citrate anticoagulation equally, while in CVVHD mode, blood collection and determination are suggested to conduct at the site before the filter to faciliate the assessment of the citrate anticoagulation efficacy.