ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005


The Latest on Twitter

Kidney Week

Abstract: TH-PO339

A Noninvasive Method for Assessing Arteriovenous Access Recirculation Using the Crit-Line® Monitor in Hemodialysis Patients: An In Silico Analysis

Session Information

  • Vascular Access - I
    November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

  • 704 Dialysis: Vascular Access


  • Maheshwari, Vaibhav, Renal Research Institute , New York, New York, United States
  • Thijssen, Stephan, Renal Research Institute , New York, New York, United States
  • Kotanko, Peter, Renal Research Institute , New York, New York, United States

Group or Team Name

  • RRI

The arteriovenous vascular access is the Achilles' heel of hemodialysis (HD). Access malfunction, often caused by stenosis or thrombosis, results in reduced access flow, increased access recirculation (AR), and lower Kt/Vurea. Measurement of access recirculation is a common method to detect fistula problems; however, existing methods are either invasive, costly, or labor intensive. We propose a novel method to measure AR using the Crit-Line® Monitor (CLM), which is non-invasive and free for existing CLM users.


The proposed method is based on an abrupt increase in ultrafiltration rate (UFR) for a brief period, which will increase the hemoglobin (Hgb) concentration at the dialyzer outlet. When a fraction of this venous return recirculates in the access, we will observe increased Hgb concentration on the CLM. We developed a mathematical model of an extracorporeal dialysis circuit. We perturb the UFR from 10 mL/min (assumed baseline) to 50 mL/min during HD. In the simulations, we start with a known AR and observe the effect of UFR perturbation on CLM-reported Hgb.


At the baseline UFR of 10 mL/min and assumed AR of 10%, when systemic Hgb concentration is 10 g/dL, the CLM Hgb concentration will be 10.04 g/dL. An increase in UFR to 50 mL/min increases the CLM Hgb concentration to 10.23 g/dL. If AR is 20%, the CLM Hgb concentration will be 10.52 g/dL (Figure 1). Per our model, the time required to observe the change in Hgb concentration is less than 3 min. These changes in Hgb concentration can be discerned by the CLM. Systemic Hgb concentration is assumed constant during the simulation period. Based on the described principle, the mathematical expression in Figure 1 can be used to calculate AR.


With a simple UFR perturbation, AR may be measured in every HD session. Our simulation results warrant validation in a clinical study.