A Study to Find Out Any Difference Between Sodium and Potassium Values on Arterial Blood Gas Analysis and Those on Serum Electrolyte Measurement

Abstract

Background: Electrolyte abnormalities, particularly sodium and potassium disturbances, are common in critically ill patients and require rapid and accurate assessment for timely management. Although central laboratory auto-analysers are considered the standard method, their longer turnaround time may delay treatment, whereas arterial blood gas (ABG) analysers provide quick results. This study compared electrolyte values obtained by these two methods to determine whether ABG values could be used for rapid clinical decision-making in emergency settings. Methodology: A hospital-based cross-sectional, observational study was conducted in the Department of Respiratory Medicine, Gouri Devi Institute of Medical Sciences and Hospital over a period of 3 months. A total of 102 patients admitted to the ICU or emergency and who fulfilled the inclusion and exclusion criteria were enrolled. Venous blood samples for sodium and potassium were collected before administration of any fluids or electrolyte correction and analysed using the Acculab Enlite Fully Automated Electrolyte Analyzer (Accurex Biomedical Pvt. Ltd., Mumbai, India). Simultaneously, arterial blood samples were analysed using the i-SmartCare 10 ABG analyser (i-SENS Inc., South Korea). Values obtained by both methods were recorded and tabulated in MS-Excel and analysed by IBM SPSS Statistics version 29.0 (IBM Corp., Armonk, NY, USA). Results: A total of 102 patients (68 males, 34 females; with a mean age of 52.47 ± 18.12 years) were studied. The mean serum sodium concentration was significantly higher than the ABG sodium concentration (136.92 ± 5.61 mmol/L versus 131.96 ± 7.19 mmol/L; p < 0.001). Similarly, the mean serum potassium concentration was significantly higher than the ABG potassium concentration (4.06 ± 0.73 mmol/L versus 3.85 ± 0.76 mmol/L; p < 0.001). Sodium showed a moderate correlation (r = 0.625) with poor agreement, whereas potassium demonstrated a strong correlation (r = 0.841) and good agreement. Thus, ABG sodium cannot replace laboratory measurements, while ABG potassium may be usable for rapid bedside assessment. Conclusion: ABG sodium measurements should not be considered interchangeable with conventional serum electrolyte measurements. Laboratory serum sodium estimation remains the preferred method for accurate clinical assessment. ABG potassium estimation is a reliable alternative for rapid assessment in emergency, life-threatening situations but should not replace laboratory testing. Key words: Arterial blood gas analyser, sodium, potassium, Laboratory Auto-analyser