Bedside monitoring of anticoagulation in chronic haemodialysis patients treated with tinzaparin

Abstract

BACKGROUND: During haemodialysis, anticoagulants are required to prevent clotting in the extracorporeal circuit. Low-molecular weight heparins (LMWH) are frequently used because of the ease of a single injection at the start of dialysis. Disadvantages of LMWH include the lack of a reliable bedside assay for measuring their anticoagulant effect. METHODS: We investigated a bedside test for LMWH activity. The relationship between anti-Xa (chromogenic assay) and Hemonox point-of-care assay was evaluated in 21 dialysis patients (12 men and 9 women) with a median age of 71 years, receiving tinzaparin at the start of a haemodiafiltration session. RESULTS: At the start, before tinzaparin administration, median (interquartile ranges) of Hemonox values were 74 (67-82) s. Thirty minutes after tinzaparin administration, Hemonox values were increased to 496 (360-736) s, followed by a decrease to 149 (135-301) s after 120 min, 102 (97-144) s after 180 min and 92 (83-100) s after 240 min. Corresponding anti-Xa activities were 0 (0-0), 1.12 (0.9-1.29), 0.74 (0.57-0.96), 0.47 (0.31-0.7) and 0.31(0.16-0.49) IU/mL. Hemonox values showed an exponential relation to anti-Xa levels. Interchangeability of tests was shown by Bland-Altman plot. CONCLUSION: Point-of-care Hemonox test is a valuable bedside method for monitoring anti-Xa activity in dialysis patients anticoagulated with tinzaparin.