Concordance of the analysis of basic biochemical and hematological parameters using a blood gas analyzer compared to laboratory analyses: a retrospective method-comparison study from a tertiary center in Morocco

Abstract

Introduction: the use of "point-of-care" (POC) monitoring, like blood gas analysis, allows clinicians to measure important variables in real-time, allowing for immediate results to be provided to make rapid decisions. However, the reliability of basic biochemistry and hematology parameters in arterial blood conducted at the point of care (blood gas analyzer) compared to a laboratory-based analyzer using venous blood is often unknown. Methods: this is a retrospective, analytical, quantitative, and cross-sectional study (n=53/200) aimed at evaluating the concordance between results obtained from a point-of-care blood gas analyser using arterial blood in an intensive care setting and laboratory-based testing using venous blood for sodium, potassium, hemoglobin and hematocrit measurements. Collected data were entered using Microsoft Excel for statistical processing. Analysis and interpretation of the results were performed using GraphPad Prism. Results: the comparative analysis indicates that measurements for sodium, potassium, and hematocrit differ significantly between the two methods, whereas hemoglobin values demonstrate relative concordance. Specifically, sodium measurements evaluated via blood gas analysis revealed a significant negative mean bias of -7.30 +/-7.13 mmol/L (p < 0.001) with wide limits of agreement ranging from -21.28 to 6.67 mmol/L, reflecting marked variability. Conversely, potassium exhibited a positive mean bias of 0.55 +/- 0.73 mmol/L (p < 0.0001) with limits of agreement spanning from -1.99 to 0.88 mmol/L. Regarding hematocrit, a significant difference was observed (p = 0.0079) with a mean bias of -2.55 +/- 6 and limits of agreement between -14.33 and 9.22%. In contrast, hemoglobin measurements showed no statistically significant divergence (p = 0.562), displaying a minimal mean bias of 0.30 +/-1.95 g/dL and limits of agreement from -4.14 to 3.52 g/dL. Conclusion: although the blood gas analysis offers the advantage of speed and immediate availability at the patient's bedside, its use should be considered with caution. These discrepancies, particularly concerning electrolytes and hematocrit, can mislead clinical reasoning as well as therapeutic management if POC results are used alone to guide treatment decisions.