Original scientific paper

https://doi.org/10.11613/BM.2020.030702

A method comparison study of a point-of-care blood gas analyser with a laboratory auto-analyser for the determination of potassium concentrations during hyperkalaemia in patients with kidney disease

Mogamat-Yazied Chothia orcid.org/0000-0002-9801-1300 ; Division of Nephrology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
Patricia Kassum ; Division of Nephrology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
Annalise Zemlin ; Division of Chemical Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University and National Health Laboratory Service (NHLS), Tygerberg Hospital, Cape Town, South Africa

Abstract

Introduction: Hyperkalaemia is a common electrolyte disorder that may cause life-threatening cardiac arrythmias. We aimed to determine the
agreement of potassium concentrations between GEM premier 3500 point-of-care blood gas analyser (POC-BGA) and Roche Cobas 6000 c501 autoanalyser
in patients with hyperkalaemia.
Methods: A prospective, cross-sectional study of all consecutive adult patients referred to the Renal Unit with a serum potassium concentration ≥
5.5 mmol/L was performed. A total of 59 paired venous blood samples were included in the final statistical analysis. Passing-Bablok regression and
Bland Altman analysis were used to compare the two methods.
Results: The median laboratory auto-analyser potassium concentration was 6.1 (5.9-7.1) mmol/L as compared to the POC-BGA potassium concentration
of 5.7 (5.5-6.8) mmol/L with a mean difference of - 0.43 mmol/L and 95% upper and lower limits of agreement of 0.35 mmol/L and - 1.21
mmol/L, respectively. Regression analysis revealed proportional systematic error. Test for linearity did not indicate significant deviation (P = 0.297).
Conclusion: Although regression analysis indicated proportional systematic error, on Bland Altman analysis, the mean difference appeared to remain
relatively constant across the potassium range that was evaluated. Therefore, in patients presenting to the emergency department with a
clinical suspicion of hyperkalaemia, POC-BGA potassium concentrations may be considered a surrogate for laboratory auto-analyser measurements
once clinicians have been cautioned about this difference.

Keywords

point-of-care; emergency department; potassium concentrations; hyperkalaemia

Hrčak ID:

244726

URI

https://hrcak.srce.hr/244726

Publication date:

15.10.2020.

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