The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

I-STAT (tm) IS NOT ACCURATE AT ESTIMATING OXYGEN TENSIONS GREATER THAN 350 TORR.

SMITH R, BROVIAK A, FAIRBANKS B, HARRINGTON J, POGULIS M, TENG E, WARD J. RRT, HELMHOLZ H, MD, FINDLAY J, MD, PLEVAK D, MD. ROCHESTER COMMUNITY AND TECHNICAL COLLEGE-MAYO FOUNDATION, ROCHESTER, MN.

Background: The i-STAT (tm) Portable Clinical Analyzer (i-STAT Corp, Princeton, NJ) is being used to estimate arterial oxygen tension (PaO_{2}). A previous study demonstrated acceptable accuracy when PaO_{2} values were < = 200 torr (Shelledy DC, Smith WA. Respir Care 1997; 42(7):693-697). We performed this investigation to determine if the i-STAT was accurate in measuring PaO_{2} at high oxygen tensions.

Methods: To be clinically useful at high PaO_{2}, we felt that the i-STAT values should be within 75 torr of those measured by a conventional IL-1306 blood gas analyzer (Instrumentation Industries, Lexington, MA). We used bias and precision data as previously described (Shelledy & Smith) to determine study sample size. An IL-237 tonometer (Instrumentation Industries, Lexington, MA) was used to increase oxygen tensions of twenty-two 2ml discarded human blood samples. The samples were split to be analyzed simultaneously in the i-STAT and IL 1306. Values for both readings were recorded and plotted using a Bland-Altman plot (see Fig. 1).

Results: Mean bias was + 48 torr. Data variability was large (± standard deviation -80 to + 120 torr) and exceeded the limits we had previously set (± 75 torr).

Conclusion: The i-STAT portable analyzer may not be accurate when measuring high oxygen tensions. Underestimations in PaO_{2} which averaged 48 torr and exceeded 120 torr could effect clinical care.

(See Original for Figure)

The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.

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