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Abstract: TH-PO259

Estimation of Pre-Dialysis Hemoglobin Concentration Using Intradialytic Crit-Line Monitor Readings

Session Information

Category: Anemia and Iron Metabolism

  • 202 Anemia and Iron Metabolism: Clinical

Authors

  • Thwin, Ohnmar, Renal Research Institute, New York, New York, United States
  • Preciado, Priscila, Renal Research Institute, New York, New York, United States
  • Tao, Xia, Renal Research Institute, New York, New York, United States
  • Patel, Samir D., Renal Research Institute, Weehawken, New Jersey, United States
  • Tapia, Mirell, Renal Research Institute, New York, New York, United States
  • Rivera, Lemuel, 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
Background

Anemia is a major complication in hemodialysis (HD) patients.The Crit-Line monitor (CLM) is widely use to determine oxygen saturation, hematocrit and hemoglobin (Hgb) levels.It would be desirable to use CLM to estimate pre-HD Hgb values to reduce blood draws.However,due to hemodilution by the priming fluid,the initial Hgb values at the HD start are consistently lower than pre-HD values.A high initial ultrafiltration rate (UFR) allows rapid removal of the priming fluid while limiting the impact associated with saline extravasation and vascular refill.Our goal was to implements a high initial UFR to evaluate the agreement between the two measurements.

Methods

Prospective,observational study in chronic HD patients.Subjects were studied 3 times.Two pre-HD blood samples were drawn, measured in triplicate by Spectra East Laboratories (Rockleigh, NJ, USA), and the average used for comparison to CLM. Initial UFR was set to 3 L/hr for 8 minutes and then returned to prescribed rate.Hgb was recorded continuously with CLM.Difference of CLM to lab Hgb value was calculated as CLM reading at each time point minus averaged lab value

Results

We included 27 subjects (56.4±15 years, 70% males, 63% African-Americans) and a total of 61 treatments.With rapid ultrafiltration, the difference between CLM and lab values decreased and reached minimal at approximately 6 minutes (Fig.1), and about 75% of subjects had CLM Hgb values that were within ±0.5 g/dL of the corresponding lab reference Hgb

Conclusion

With a high initial UFR, 75% of CLM Hgb values were within ±0.5 g/dL difference of the averaged lab measurement at minute 6.Of note, the lab values are afflicted with some degree of measurement variability contributing to the data spread.Next steps should include development of mixed effects models for prediction of an individualized time point at which to read CLM Hgb,to further increase the agreement between the two methods.

Fig.1. Delta of lab and CLM Hgb values at each time point for the first 20 minutes of HD