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Volume 1, Number 1 (2023)
Year Launched: 2023
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Construction of a Mathematical Model for Conventional Haemodialysis and Continuous Renal Replacement Therapy in Subjects with Hyponatraemia or Hypernatraemia and/or hyperkalaemia

Volume 1, Issue 1, January 2023     |     PP. 1-26      |     PDF (1187 K)    |     Pub. Date: December 5, 2023
DOI: 10.54647/ajnu1101002    54 Downloads     37383 Views  

Author(s)

Keng-Hee Koh, Medical Department, Miri Hospital, Ministry of Health, Malaysia.

Abstract
Background:
Dialysis in patients with dysnatraemia and hyperkalaemia is generally difficult because needing to minimize [Na] correction while ensure rapid [K] correction, and thus a need for mathematical model.
Methods:
A model was derived with 80 regular ESRD dialysis sessions and 10 acute dialysis (AD) sessions. Clinical audit was performed assessing error of this model with new set of 33 AD of HD and CRRT with [Na] <=130 or >=150mmol/L pre-dialysis.
Results:
Na prediction could be derived with dialysate flow rate (Qd) clearance calculation and solute transport, assuming that all plasma flow is changed to the dialysate Na concentration, i.e., Qd with limit by plasma flow rate. However, a refined calculation was for intracellular solute such as K and urea, for Qd being multiplied by the factor of: Blood water flow rate / (blood water flow rate + dialysate flow rate), i.e., BWFR/ (BWFR+Qd).
And, because of varying “volume of distribution”, the total body water (TBW) needs to be adjusted with fuzzy factor, namely fNa, fK, and furea, which were determined as 0.846, 1.931, and 1.128 respectively (of Watson TBW). Extracellular electrolyte has lower fuzzy factor than predominant intracellular electrolyte.
The errors in absolute number for serum Na, K, urea and osmolarity estimation prediction were 1.8 ±1.3, 0.32 ±0.34, 2.3 ±1.9 and 3.8 ±3.2 mmol/L, respectively. Good reliability and correlation were shown between predicted and measured parameters.
Conclusion:
Model substantiates fuzzy factor correction for TBW, and also dialysis clearance calculation with Qd limit by plasma flow rate for extracellular electrolyte, and in contrast, the need of Qd dilution by factor of (BWFR/(BWFR+Qd)) for intracellular electrolyte. Low errors in absolute number between predicted and actual electrolyte were shown.

Keywords
Haemodialysis, Continuous Renal Replacement Therapy, Hyponatraemia, Hypernatraemia, Hyperkalaemia, Acute Kidney Injury, End Stage Kidney Disease

Cite this paper
Keng-Hee Koh, Construction of a Mathematical Model for Conventional Haemodialysis and Continuous Renal Replacement Therapy in Subjects with Hyponatraemia or Hypernatraemia and/or hyperkalaemia , American Journal of Nephrology and Urology. Volume 1, Issue 1, January 2023 | PP. 1-26. 10.54647/ajnu1101002

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