The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

A COMPARISON OF THE i-STAT SYSTEM AND CORNING 278 FOR THE MEASUREMENT OF ARTERIAL BLOOD GAS VALUES.

Wayne A. Smith, CRTT, David C. Shelledy, PhD, RRT, The University of Texas Health Science Center at San Antonio, Texas.

BACKGROUND: The i-STAT system (i-STAT Corp., Princeton, NJ) is a point- of-care blood analysis device allowing for measurement of arterial blood gas values at the bedside. We compared the performance of the i-STAT to the conventional Corning 278 blood gas analyzer (Ciba Corning Diagnostics Corp., Norwood, MA). METHOD: One hundred nineteen consecutive blood gas samples were analyzed using the i-STAT system and Corning 278 concomitantly. Mean pH, PaCO_{2} and pH values were compared using the t-test for dependent samples to determine if there were significant differences (p < .05). Pearson product moment correlations were calculated to determine if there were significant correlations (p < .05) between the two instruments. Results: Means, standard deviations, t and p values were as follows:

Corning 278 i-STAT t p

pH 7.4024 (.06) 7.4075 (.07) -2.47 .015

PaCO_{2} 42.9927 (9.9) 43.442 (10.2) -2.43 .017

PaO_{2} 107.85 (73.1) 109.73 (76.6) -1.88 .062

Regression equations were:

i-STAT pH = -.2174+1.0301 x Corning pH

i-STAT PaCO_{2} = -.1724+1.0145 x Corning PaCO_{2}

i-STAT PaO_{2} = -2.138+1.0373 x Corning PaO_{2}

There were small, but statistically significant differences between the two instruments for pH and PaCO_{2}. There was no significant difference for PaO_{2}. There were significant correlations between values obtained with the i-STAT when compared to the Corning 278 for pH (r = .9392; p < .01), PaCO_{2} (r = .9804, p < .01) and PaO_{2} (r = .9904, p < .01). Conclusions: Arterial blood gas results obtained via the i-STAT system correlated well with results obtained with the Corning 278. There were small, but statistically significant differences between the two instruments on pH and PaCO_{2}, however, these differences were probably not clinically significant.

Reference: OF-96-144

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