Clinical research of hemodialysis adequacy evaluation with Kt/V by on-line clearance monitoring and by blood sampling calculation

Objective To evaluate the value of on-line clearance monitoring (OCM) in hemodialysis adequacy evaluation. Methods 135 maintenance hemodialysis patients were investigated by using OCM appliance, including 66 males and 69 females, with the mean SD age of (63.3±15.9) years old. Meanwhile, blood urea nitrogen (BUN) in pre-and post-dialysis periods was examined to calculate Kt/V based on the equation of Daugirdas Ⅱ. We then evaluated the correlation between the two methods, and analyzed the clinical factors influencing the OCM. Results Kt/V value by OCM (Kt/Vocm) and by calculation (Kt/VD) was (1.25±0.33) and (1.44±0.30), respectively, and the correlation coefficient was 0.512 (P<0.001). Height, body weight and blood flow were independent factors of Kt/Vocm. Body weight and height were negatively correlated with Kt/VocmOR=-0.412 (P<0.001), 95%CI (-0.015, -0.006); OR=-0.240 (P=0.01), 95%CI (-0.015,-0.002), respectively, while blood flow was positively correlated with Kt/VocmOR=0.349 (P<0.001), 95%CI (0.003, 0.008). According to whether Kt/Vocm was more than 1.2, the patients were divided into two groups, and the differences in clinical data between them were compared. The sex, urea reduction ratio (URR), body weight, fasting blood glucose, body surface area, and hemodialysis blood flow were significantly different between the two groups. Conclusions Kt/Vocm is significantly related with that by calculation. Kt/Vocm is lower than that by calculation, which is affected by height, body weight and blood flow. Therefore, OCM can reflect the urea clearance of patients on single dialysis, and can be used as a simple and reliable indicator of clinical adequacy of hemodialysis.