Comparison of the Potassium Concentrations Measured by Using Blood Gas Analyzers and Automated Chemical Analyzers

ABSTRACT

PURPOSE: Critically ill patients frequently require rapid measurements of serum potassium. Analyses of serum samples take some time, but the results of blood gas analyses are often available more promptly. This study aims to determine the correlation between potassium concentrations measured by blood gas analyzer and automated chemical analyzer with a view to identifying whether the plasma potassium level can be used as an alternative to the serum values in the clinical management of selected patients in the Emergency Department (ED). METHODS: This prospective study of patients who were deemed by their treating doctor to require a blood gas analysis and chemistry analysis compared the potassium concentrations obtained from plasma and serum taken simultaneously. Data were analyzed using a Pearson correlation and a linear regression. RESULTS: Four hundred ninety-six patients were entered into the study. The potassium concentrations measured using two blood gas analyzers and two automated chemical analyzers were relatively highly correlated (coefficient=0.871), with an average difference between two methods of 0.449 mmol/L. There was also a high level of agreement between the methods with the 95% limits of agreement being -0.2 to 1.2 mmol/L. CONCLUSION: Compared with data from other previous test, our data were unsatisfactory. However our trial makes it possible in our ED to obtain serum potassium level from the plasma level. In addition, hypokalemia obtained by blood gas analyzer should be made an exception in treating it.