Pradhan J, Harding AM, Taylor SE, Lam Q. Implications of differences between point-of-care blood gas analyser and laboratory analyser potassium results on hyperkalaemia diagnosis & treatment.
Intern Med J 2023;
53:2035-2041. [PMID:
36645311 DOI:
10.1111/imj.16020]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/08/2023] [Indexed: 01/17/2023]
Abstract
BACKGROUND
Hyperkalaemia is managed in the emergency department (ED) following measurement of potassium results by blood gas analysers (BGA) or laboratory analysers (LAB).
AIMS
To determine the prevalence of clinically significant differences between BGA and LAB potassium results and the impact on ED hyperkalaemia management.
METHODS
Retrospective analysis of time-matched ED BGA and LAB potassium samples from 2019 to 2020 (taken within 15 min, one or both results ≥6.0 mmol/L). Mean differences and 95% limits of agreement (LoA) were determined for pairs with one or both results ≥6.0 mmol/L and a separate 500 consecutive sample pairs.
RESULTS
Four hundred eighty-eight matched BGA and LAB samples met the inclusion criteria. Of these, 201 (41.2%) differed by ≤0.5 mmol/L, 169 (34.6%) included a haemolysed LAB sample, and 12 (2.5%) had an unreportable BGA sample. One hundred six (21.7%) pairs differed by >0.5 mmol/L, and 60/106 (57%) had normal LAB potassium results, but BGA indicated moderate/severe hyperkalaemia (two of these pairs received hyperkalaemia treatment). Of patients with a haemolysed LAB sample, or where pairs differed by >0.5 mmol, 48 were treated with insulin and five (10.4%) experienced hypoglycaemia. Mean differences and LoA for pairs with LAB results <6.0 mmol/L but BGA ≥6.0 mmol/L demonstrated unacceptable agreement, with 18 (25.7%) BGA results exceeding 8.0 mmol/L.
CONCLUSIONS
Potentially significant discordance may occur between BGA and LAB potassium results. Clinicians need to be aware of factors impacting both analytical methods' accuracy (such as poor venepuncture or sample handling, (K) EDTA interference) and undetectable haemolysis with BGA measurements. We recommend BGA hyperkalaemia be confirmed with LAB results using a non-haemolysed sample where time permits.
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