Reliability of Point-of-Care Venous Blood Gas Testing for Potassium and Sodium Compared to Central Laboratory Results in Emergency Patients: A Clinical Audit.

Background Point-of-care testing (POCT) is widely employed in emergency departments (EDs) for rapid clinical decision-making. However, the reliability of POCT for assessing critical electrolytes like potassium (K⁺) and sodium (Na⁺), compared to central laboratory methods, remains under scrutiny. Objective This quality improvement (QI) study aimed to evaluate and improve the reliability of POC venous blood gas (VBG) testing for K⁺ and Na⁺ by comparing results with central laboratory values. Structured within a Plan-Do-Study-Act (PDSA) cycle, the objectives included quantifying the analytical concordance using Pearson correlation and Bland-Altman methods, identifying systematic bias or clinical outliers, and assessing turnaround time (TAT) to inform iterative improvements in POCT protocol integration within the ED. Methods A retrospective audit was conducted on 120 patients (N = 120, 100%) at Fakeeh University Hospital, Dubai, from March to May 2023. Paired K⁺ and Na⁺ values from POCT VBG analyzers and laboratory reports were compared. Statistical analysis included scatter plots, Pearson correlation, and Bland-Altman agreement. Results Of the 120 patients, 65 (54.2%) were male and 55 (45.8%) were female, with a mean age of 47.3 years (SD = 16.1). Chief presentations included chest pain (N = 38, 31.7%), dyspnea (N = 32, 26.7%), vomiting (N = 23, 19.2%), and signs of dehydration (N = 27, 22.5%). POCT K⁺ and Na⁺ values showed strong correlation with laboratory values (r = 0.91 and r = 0.88, respectively). The mean bias for K⁺ was +0.12 mmol/L, and for Na⁺ it was -1.2 mmol/L. TAT was significantly shorter for POCT (mean = 2.4 minutes) versus laboratory results (mean = 12.3 minutes), with a median delay of 10 minutes. Conclusion POCT demonstrated high reliability for K⁺ and Na⁺ evaluation in EDs. However, caution is advised when interpreting extreme values, especially hyperkalemia (> 5.5 mmol/L). Central laboratory confirmation should be considered in borderline or critical cases.