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Abstract: FR-PO496

Discrepancy Between In Vivo and In Vitro (Dialyzer Mass Transfer-Area Coefficient) KoA in Patients on Chronic Intermittent Hemodialysis (IHD): A Retrospective Analysis

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Agarwal, Neil Kumar, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Plotskaya, Natalia, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Ahmed, Ziauddin, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Kelepouris, Ellie, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Goldman, Jesse M., Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Aggarwal, Sandeep, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
Background

KoA is a measure of the dialysis membranes clearance efficiency. Manufacturer KoA values are determined from in-vitro studies. The achieved in-vivo KoA using these membranes in IHD is not known.

Methods

We retrospectively reviewed measured hemodialysis kinetic results in 70 patients receiving IHD at an outpatient free-standing dialysis unit. Over a 2-month period, we reviewed 140 dialysis sessions. Age, Gender, Weight, Height, length of session, blood flow rate (Qb), dialysate flow rate (Qd), pre-BUN, post-BUN, urea reduction rate (URR), type of dialyzer and manufacture KoA, UF, pre-weight, post-weight and spKt/V were recorded. Specimens were obtained according to specifications of the dialysis unit. We then calculated the Kt/V using Daugirdas 2 equation (D2), body surface area (m2) calculated using Mostellar equation (M-BSA), and total body water (L) calculated using Watson’s formula (W-TBW). MS Excel® was used for mathematical calculations (“what if analysis”) and IBM SPSS® v22 was used for statistical analysis – correlations and t-tests. In-vivo KoA was back calculated from D2 using AS Michaels equation:
Clearance (K) = Qb ((exp(KoA(1-Qb/Qd)/Qb) -1)/(exp(KoA(1-Qb/Qd)/Qb) -1)-b/Qd))

Results

There were 70 patients, 39 females, mean age 58.9±13.4 years, mean time on HD 233±18 minutes, mean Qb 404±44.8 mL/min, mean Qd 800±0 mL/min, mean pre-BUN 53.7±21.3 mg/dL, mean post-BUN 14.6±7.2 mg/dL. Of the 140 IHD sessions, 2 were excluded for incomplete data. When comparing Kt/V, calculated using manufacture KoA with Michaels equation, we found a moderate correlation to UKM (r = 0.5646, p=0.0001). When comparing D2 to UKM, we found a strong positive correlation (r=0.97, p=0.0001). When compared, the in vitro KoA (1231±116ml/min) was 72.8% lower than in vivo KoA (340±156ml/min), mean difference 891±17mL/min (p=0.0001). The reduction in KoA (rKoA) was calculated using equation: 1-(in-vivo KoA/ in vitro KoA). rKoa had a strong positive correlation to body surface area (r=0.8, p=0.0001) and W-TBW (r=0.83, p=0.0001), but no other significant correlations could be discovered.

Conclusion

Our study showed a significantly lower in vivo KoA as compared to in vitro KoA. Larger studies are needed to further evaluate the variables affecting the in-vivo KoA.