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Hemodialysis.com | Hemofiltration Measurement of Vascular Access Flow by OCM | Dr. Tiranathanagul

Author Interview: Khajohn Tiranathanagul, MD

Division of Nephrology, Department of Medicine
King Chulalongkorn Memorial Hospital, Thai Red Cross Society and
Faculty of Medicine, Chulalongkorn University
Bangkok, Thailand

Author Interview: Khajohn Tiranathanagul, MD

Measurement of Vascular Access Flow by Online Clearance Monitor in Online Hemodiafiltration.

Tiranathanagul K, Susantitaphong P, Towannang P, Injan P, Praditpornsilpa K, Eiam-Ong S.

Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital

What are the main findings of the study?

The vascular access (VA) flow rate (Qa) determined by two measurements of ionic dialysance or online clearance in normal and reverse blood line positions was highly accurate and easy to perform in online HDF (OL-HDF) method. Although this technique has been proven the accuracy in hemodialysis method, it has never been reported in OL-HDF method. In addition, this study described the correct method of applying the OCM (online clearance monitoring) function which is integrated in Fresenius HDF machine for this Qa measurement and demonstrated that it was economical and could be used for vascular access surveillance in OL-HDF.

Were any of the findings unexpected?

No, they were not unexpected findings although the recent former study using OCM for Qa measurement in HD reported unreliable results [Eloot S, et al. Blood purification 2010;30:89-95]. Our present study could provide the reader the more accurate method for using OCM in Qa measurement that was not attained in the former negative study. 

What should clinicians and patients take away from this study?

Application of OCM for VA measurement in OL-HDF is highly accurate, easy to perform, and economical in OL-HDF therapy. Therefore, the OCM technique could be routinely used to determine and follow the Qa in a surveillance protocol as a reliable alternative to the ultrasound dilution technique (UDT).

What recommendations do you have for nephrology health care providers as a result of your study?

Regular measurement of the Qa by any accurate indirect Qa measurement techniques is the best way for surveillance and predicting failure of the access. Various practical and economical techniques beside the standard UDT were available. The best choice in each HDF and HD centers might be variable. This result of our study would ensure the clinicians who want to use the available OCM function in HDF machine for VA flow rate measurement in their VA surveillance program.


Background: Measurement of ionic dialysance has been shown to accurately determine urea dialyzer clearance and vascular access flow rate (Qa) in diffusive hemodialysis. Recently, online clearance monitoring (OCM) in an online hemodiafiltration (OL-HDF) machine could accurately measure urea dialyzer clearance.

In the present study, OCM was utilized to assess the Qa in OL-HDF. Methods: In 32 stable end-stage renal disease patients undergoing predilution OL-HDF, the values of Qa measured by the OCM technique (Qa(OCMT)) in a Fresenius 4008H HDF machine were compared with those determined by the standard ultrasound dilution technique (Qa(UDT)).

Results: The values of Qa(UDT) and Qa(OCMT) measured at the beginning of the HDF session were 800.5 ± 910.3 and 794.6 ± 895.4 ml/min (nonsignificant). There was a significant correlation between the two techniques (r = 0.95, p < 0.01). A Bland-Altman plot demonstrated a good agreement.

Conclusion: The vascular access flow determined by OCM, which is integrated mostly in the current HDF machine, is highly accurate, easy to perform, and economical and can be used for vascular access surveillance in OL-HDF.

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