Accuracy of the i-STAT (TM) bedside blood gas analyser

The performance of the i-STAT portable clinical analyser for measuring bloo d gases and pH was evaluated,vith reference to a conventional blood gas ana lyser (ABL520 Radiometer). Ninety-two samples from the routine blood gas analysis laboratory were chos en according to a wide distribution of partial pressure of carbon dioxide ( Pa,CO2), partial pressure oxygen (Pa,O-2) and pH and then analysed. All mea surements were performed in duplicate by trained technicians from the centr al hospital laboratory. Differences between duplicate measurements were computed for Pa,CO2: (1.2 v ersus 0.4%), Pa,O-2 (1.7 versus 1.1%) and pH (0.06 versus 0.02%), for the i -STAT and ABL520, respectively. pH and Pa,CO2 values measured with the i-ST AT were very close to those obtained with the ABL520, the difference (mean/-sD) being 0.006+/-0.018 and -0.13+/-0.17 kPa, respectively. Statistical a nalysis showed that the differences between analysers did not depend on val ues of pH or Pa,CO2 The performance of the analysers depended on the level of PO2. Below 15 kPa (n=48), the two systems gave nearly identical values, the mean difference was 0.01+/-0.37 kPa. Between 16 and 55 kPa (n=44), ther e was a systematic but small (-0.69+0.67 kPa) underestimation of Pa,O-2 mea sured with the i-STAT (p<10(-8)). In conclusion, this study shows that blood gas analysis using the i-STAT po rtable device is comparable,vith that performed by a conventional laborator y blood gas analyser.