Analytical Agreement Between ABL90 FLEX and GEM Premier 5000 Blood Gas Analyzers in Arterial Whole Blood Samples

Objectives: Point-of-care blood gas analyzers are essential in acute care settings because of their rapid turnaround time and integrated quality control. However, analytical variability between platforms may influence clinical interpretation. This study aimed to evaluate the analytical agreement between the ABL90 FLEX and GEM Premier 5000 blood gas analyzers in arterial whole blood samples.
Methods: A total of 433 arterial samples were collected at Zonguldak Bulent Ecevit University Hospital; 406 samples met the inclusion criteria and were analyzed consecutively on the ABL90 FLEX and GEM Premier 5000 within 2 minutes. Parameters included blood gases, electrolytes, co-oximetry fractions, metabolic analytes, and calculated values. Statistical analysis was performed using Pearson correlation, Passing–Bablok regression, and Bland–Altman analysis.
Results: pH and pCO₂ showed strong agreement (r=0.880 and 0.957, respectively), with minimal bias (−0.003 and −1.34, respectively) and no significant difference (p>0.05). No significant differences were observed for ionized calcium, chloride, methemoglobin, total bilirubin, or lactate (p>0.05). Significant differences were detected for pO₂, SO₂, sodium, potassium, glucose, bicarbonate, osmolality, and co-oximetry parameters (p<0.05). Bland–Altman analysis showed narrow limits of agreement for acid–base parameters but wider bias for pO₂ (1.63) and SO₂ (1.24). Passing–Bablok regression demonstrated proportional bias for oxygenation indices, sodium, and O₂Hb, with significant deviation from linearity in several parameters, indicating limited interchangeability between analyzers for oxygenation and derived measurements. Conclusion: The ABL90 FLEX and GEM Premier 5000 provide comparable results for key acid–base and selected metabolic parameters, whereas oxygenation indices, sodium, and some co-oximetry fractions require cautious interpretation and consistent platform use for serial monitoring.

Keywords: ABL90 FLEX, GEM Premier 5000, pCO₂,, pH, pO₂