Abstract: 【Abstract】Objective To investigate the effect of heparin concentration for catheter lock on conventional coagulation functions and thromboelastograph (TEG). Methods Fifty patients treated with continuous renal replacement therapy (CRRT) using local citrate anticoagulation were randomly divided into two groups according to lock heparin concentration: group A (6,250U/ml) and group B (3,125U/ml). Blood routine tests, conventional coagulation tests and TEG were performed before CRRT, after CRRT and before catheter lock, and after catheter lock for 30 min. TEG disposable heparinase cups and pins were measured 30 min after lock. The incidences of bleeding and thrombosis in 24 hours were recorded. Results ① There were no significant differences in PLT, prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) between before CRRT and after CRRT (P＞0.05). PT, APTT and TT were significantly prolonged after lock for 30 min in both groups (P＜0.05), and APTT and TT were longer in group A than in group B (P＜ 0.05). ②There were no significant differences in TEG R values before CRRT and after CRRT in both groups (P＞0.05). The R values were significantly extended after lock for 30 min in both groups, especially in group A (P＜0.05). No blood clot was found in 9 cases in group A and 5 cases in group B. After neutralization with heparinase, the R values returned to normal in both groups. ③There was no thrombosis in both groups, but bleeding episodes were found in both groups especially in group A (P＜0.05). In 7 cases with remarkable bleeding, bleeding ceased after protamine treatment through monitoring TEG. Conclusions CRRT patients are at high risk of bleeding after catheter lock with 6,250U/ml or 3,125U/ml heparin. TEG can be used to analyze the cause of bleeding and to guide protamine therapy in case of coagulation dysfunction.

Key words: Heparin, Catheter Lock, Thromboelastograph