Analytical Performances of the Novel i-STAT Alinity Point-of-Care Analyzer

Abstract

Many Point-of-Care devices have been released over the past decade. However, data regarding their analytical performances in real-world situations remains scarce. Herein, we aimed to assess the analytical performances of the i-STAT Alinity system. We conducted an analytical performances study with the i-STAT Alinity device using cartridges CG4+ (pH, Pco2, Po2, lactate, bicarbonate and base excess); CHEM8+ (Na, K, Cl, ionized Ca, urea, creatinine, glucose, hematocrit and hemoglobin) and PT/INR (prothrombin time and international normalized ratio). We assessed the imprecision and compared the results to those obtained on existing instruments in the central laboratory. We found that the within-lab coefficients of variation (CV) were very low (<2%) or low (2−5%), except for creatinine and PT (CV = 5.2% and CV = 6.3%, respectively). For almost all the parameters, the results were strongly (R2 = 90−95%) or very strongly (R2 > 95%) correlated with those of the existing laboratory instruments, and the biases were very low (<2%) or low (2−5%). However, correlations of the PT and INR measurements with existing instruments were lower (R2 = 86.0% and 89.7%), and biases in the Po2 (7.9%), creatinine (5.4%) and PT (−6.6%) measurements were higher. The i-STAT Alinity appeared as a convenient device for measurements of numerous parameters. However, clinicians should interpret Po2, creatinine and PT results with caution.

Keywords: Point-of-Care Analyzer; analytical performance; blood gas; chemistry; coagulation; creatinine; hematology; i-STAT Alinity; lactate; urea.

Figure 1

Passing–Bablok regressions of pH, partial pressure of oxygen (Po2), bicarbonate, lactate, glucose, sodium (Na), potassium (K), chloride (Cl) and ionized calcium (iCa), hematocrit and hemoglobin on the iSTAT Alinity (y axis) and ABL 90 Flex Plus (x axis) analyzers; creatinine, estimated glomerular filtration rate (eGFR) and urea on the iSTAT Alinity (y axis) and Cobas 8000 (x axis) analyzers and prothrombin time (PT) and international normalized ratio (INR) on the iSTAT Alinity (y axis) and ACL TOP analyzers (x axis). Bland–Altman plots of differences against means for patient samples (N = 49, except for creatinine and urea: N = 45, and PT and INR: N = 46) measurements with the iSTAT Alinity and central laboratories’ analyzers represented with the mean (dashed green line) and limits of agreement (dashed red lines) of the bias.