Preliminary clinical trial of an ex vivo arterial blood gas monitor.

PURPOSE

The purpose of this study was to test the analytical performance of a new ex vivo arterial blood gas (ABG) monitor based on fiberoptic sensor technology (SensiCath; Optical Sensors, Inc., Minneapolis, MN) when operated by critical care practitioners in intensive care environments.

MATERIALS AND METHODS

Arterial blood analyses using a new ex vivo ABG monitor and standard clinical laboratory bench top analyzers were compared according to an institutionally approved protocol. The subjects were adult intensive care unit (ICU) patients (n = 20) with an arterial cannula for pressure monitoring, expectation of ICU stay > 72 hours, need for > or = 2 ABG analyses per day, and written informed consent. The clinical setting was two ICUs, a shock trauma ICU, and a neurological ICU in a metropolitan area trauma center.

RESULTS

One hundred seventy-five paired ABG analyses were obtained over 1,146 hours of monitor use (52 +/- 20 hours per patient). Comparison of ABG monitor and laboratory analyses of blood samples obtained at the time of measurement by the monitor provided the following results: For pH, the range of laboratory measurements was 7.197-7.512, accuracy (mean difference between the monitor and laboratory measurement) was +0.010, precision (standard deviation of the difference between monitor and laboratory measurements) was +/- 0.027, and the correlation coefficient (r) = 0.913. For PCO2, the range of laboratory measurements was 24.5-61.5 mm Hg, accuracy was +1.4 mm Hg, precision was +/- 3.3 mm Hg, and r = 0.942. For PO2, the range of laboratory measurements was 47.3-163.3 mm Hg, accuracy was +4.0 mm Hg, precision was +/- 7.9 mm Hg, and r = 0.970. No adverse events occurred associated with the monitor.

CONCLUSION

A practical ex vivo ABG monitor has been developed that offers accurate data and potential advantages to the critical care practitioner and the critically ill patient over other ABG analysis systems: one 10-minute calibration procedure; 1-minute analysis time; no permanent blood removal from the patient; and a closed arterial monitoring system. Precision performance is comparable to standard laboratory ABG analysis. The ABG monitor offers reliability and ease of use, and the ability of the critical care practitioner (nurse, respiratory therapist, or physician) to obtain accurate ABG analyses as needed at bedside.