ACCURACY AND PRECISION OF A NEW, PORTABLE, HAND-HELD BLOOD-GAS ANALYZER, THE IRMA(R)

Objective. The accuracy and precision of the new IRMA(R) (Immediate Re sponse Mobile Analysis System, Diametrics, Inc.(R), St. Paul, MN) hand held blood gas analyzer was compared with that of two benchtop blood g as analyzers. The IRMA consists of a notebook-sized machine and dispos able cartridges, each containing a pH, a CO2 and an O-2 electrode, and provides bedside (point-of-care) blood gas analysis. Methods. A total of 172 samples (arterial and mixed venous) were obtained from 25 info rmed, consenting patients undergoing cardiopulmonary bypass. The pH, P CO2 and PO2 of each sample was determined on four blood gas analyzers: NOVA Statlabs Profile 5 (NOVA Biomedical, Waltham, MA), the ABL-50 (R adiometer, West Lake, OH), and two IRMA machines. Linear regression an d bias +/- precision were determined, comparing each of the analyzers with the NOVA. Results. All three machines showed a similar, high degr ee of correlation with the NOVA for pH, PCO2, and PO2. The bias and pr ecision of the IRMA machines compared with the NOVA was similar to tha t of the ABL compared with the NOVA for pH (NOVA:ABL -0.005 +/- 0.011; NOVA:IRMA 1 = 0.0026 +/- 0.025; NOVA:IRMA 2 = 0.0021 +/- 0.025), for PCO2 (NOVA:ABL = -1.4 +/- 1.3 mmHg; NOVA:IRMA 1 = -1.3 +/- 1.9 mmHg; N OVA:IRMA 2 = -1.2 +/- 2.1 mmHg) and PO2 (NOVA:ABL = 3.6 +/- 21.1 mmHg; NOVA:IRMA 1 = 3.4 +/- 19.9 mmHg; NOVA:IRMA 2 = 6.3 +/- 20.9 mmHg). Th e bias found for pH, PCO2, and PO2 was not affected by extremes of tem perature (range 25.5-40 degrees C) or hematocrit (range 11-44%) for an y machine. Conclusions. The new technology incorporated in the IRMA bl ood gas analyzer provides results with an accuracy that is similar to that of benchtop analyzers, but with all of the advantages of point-of -care analysis.