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Abstract: SA-PO427

Feasibility of Crit-Line®-Based Estimation of Pre-Dialysis Hemoglobin in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Thwin, Ohnmar, Renal Research Institute, New York, New York, United States
  • Wang, Lin-Chun, Renal Research Institute, New York, New York, United States
  • Tao, Xia, Renal Research Institute, New York, New York, United States
  • Haq, Zahin Sultana, Renal Research Institute, New York, New York, United States
  • Wang, Xin, Renal Research Institute, New York, New York, United States
  • Wang, Xiaoling, Renal Research Institute, New York, New York, United States
  • Zhang, Hanjie, Renal Research Institute, New York, New York, United States
  • Rivera Fuentes, Lemuel, Renal Research Institute, New York, New York, United States
  • Grobe, Nadja, 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

Most patients on hemodialysis (HD) have renal anemia. Anemia management involves periodic collection of pre-dialysis blood samples for measurement of hemoglobin (Hgb) concentration. Replacing these blood draws by non-invasive measurements with the Crit-Line® Monitor (CLM) would be desirable but requires adjusting the measurements to reflect the customary pre-HD laboratory values. We explored whether such an adjustment is feasible.

Methods

Chronic HD patients were studied on up to 3 occasions each. Pre-HD blood was collected, and the mean of 20 repeated Hgb measurements was used as a highly accurate estimate of true Hgb concentration. CLM hematocrit was obtained 3.5 min into HD, converted into Hgb using a conversion factor of 0.322, and adjusted as per Equation 1 (patent app. WO2015/179523 A1). Bood volume was estimated using the Nadler equation, and the saline half-life was estimated to be 25 min.

Results

We studied 14 subjects (age 56.7 ± 16 years, 50% males) during a total of 27 HD treatments. The difference between adjusted CLM Hgb and pre-HD laboratory Hgb was −0.05 ± 0.55 g/dL (Figure 1; N = 25; CLM data unavailable for 2 visits).

Conclusion

Infusion of the extracorporeal priming fluid into the patient causes initial hemodilution. Equation 1 yields adjusted CLM Hgb values that are on average virtually identical to pre-HD laboratory measurements of Hgb. The observed variability may be due to inaccuracies in anthropometric blood volume assessment and variability in saline extravasation rate.