INTRODUCTION: We compared the performance of a point-of-care measurement system to that of a conventional blood gas analyzer. METHODS: One hundred nineteen arterial blood gas samples from 2 hospitals were analyzed using the i-STAT system and Corning 278 concomitantly. Values were compared using the t test for dependent samples and the Pearson product moment correlations (p < 0.05), and regression equations were calculated to determine the slope and intercept of the regression line for paired values of pH, PaCO2, and PaO2. Mean and standard deviations (SD) were also calculated for the difference between the paired results for each variable. RESULTS: Means and SD for the Corning 278 versus the i-STAT for pH were 7.40 (0.06) versus 7.41 (0.07), for PaCO2 43.0 (9.9) torr versus 43.4 (10.2) torr and for PaO2 107.9 (73.1) versus 109.7 (76.6) torr. Regression equations were:
i-STAT pH = -0.2174 + 1.0301 × Corning pH
i-STAT PaCO2 = -0.1724 + 1.0145 × Corning PaCO2
i-STAT PaO2 = -2.138 + 1.0373 × Corning PaO2.
Small, but statistically significant differences between the 2 instruments for pH (p = 0.015) and PaCO2 (p = 0.017) were obtained but no significant difference for PaO2 (p = 0.062). Significant correlations between values were obtained with the i-STAT when compared to the Corning 278 for pH (r = 0.9392; p < 0.001), PaCO2 (r = 0.9804, p < 0.001), and PaO2 (r = 0.9904, p < 0.001). Mean (SD) differences for the paired results between the 2 systems were -0.005 (0.02) for pH; -0.449 (2.02) torr for PaCO2, and -1.88 (10.9) for PaO2. CONCLUSIONS: Results obtained via the i-STAT system correlated well with results obtained with the Corning 278. Small, but statistically significant differences between the 2 instruments on pH and PaCO2 are probably not clinically important.
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