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Abstract: PO0930

Intradialytic and Interdialytic Urea Dynamics in Blood and Cerebrospinal Fluid in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Tao, Xia, Renal Research Institute, New York, New York, United States
  • Wang, Lin-Chun, Renal Research Institute, New York, New York, United States
  • Wang, Xin, Renal Research Institute, New York, New York, United States
  • Thwin, Ohnmar, Renal Research Institute, New York, New York, United States
  • Grobe, Nadja, Renal Research Institute, New York, New York, United States
  • Patel, Amrish U., Renal Research Institute, New York, New York, United States
  • Thijssen, Stephan, Renal Research Institute, New York, New York, United States
  • Chao, Joshua Emmanuel, Renal Research Institute, New York, New York, United States
  • Debure, Ludovic, NYU School of Medicine, New York, New York, United States
  • Wisniewski, Thomas, NYU School of Medicine, New York, New York, United States
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
Background

Modern,highly efficient hemodialysis (HD) results in rapid decline of blood urea. Urea gradients across the blood-brain barrier (BBB) can drive water movements. A positive urea gradient, i.e. brain urea to plasma urea, can result in brain swelling and impair brain function. We explored the dialytic changes of urea in blood and cerebrospinal fluid (CSF) to better understand intradialytic osmotic gradients across the BBB and provide insights that support the development of brain-protective HD.

Methods

Two HD patients (39 and 26 years old) with ventriculo-peritoneal (VP) shunts were enrolled into this one-week IRB-approved study with a Monday/Wednesday/Friday dialysis schedule. CSF was collected via VP shunt tap 2 hrs before and 2 hrs after HD (Wednesday and Friday), and Tuesday and Thursday. Plasma samples were collected concurrently with CSF and during HD. In addition, the patients underwent test of executive function (Trail Making Test Part B; TMT B) and global cognitive function (Montreal Cognitive Assessment; MoCA) on Monday.

Results

Urea was removed efficiently from patients’ blood by HD. While patient A showed a small post-HD plasma-to-CSF urea gradient, it was highly positive (~ 60 mg/dL) in patient B (Fig. 1). TMT B and MoCA score were normal for patient A but not patient B (TMT B 415 sec; TMT B error count: 2; MoCA score: 11).

Conclusion

Our patients showed very different post-HD plasma-to-CSF gradients. Theoretically, the positive gradient in patient B would favor intradialytic brain swelling. Patient B showed impaired neurological testing results which are not related to patient’s pre-existing neurological conditions. We can only speculate if and to what extent trans-BBB water movements driven by dialytic urea dynamics may have impacted the patient’s cognitive functions.We believe that patient-specific levels of osmotic stress need to be considered when developing neuro-protective HD technologies.