METHODS: We consulted the specification sheet of the Radical-7 to determine the accuracy of that device. Then, we generated an SaO2 figure for paO2 values that were allowed to vary between forty and one hundred torr, in one-torr increments, for this alkalemic data set using a polynomial equation originally described by G. Richard Kelman (Kelman GR. Digital computer subroutine for the conversion of oxygen tension into saturation. J Appl Physiol 1966; 21: 1375-1376). Next, we implemented the on-board algorithm incorporated within the i-STAT for this profoundly alkalemic blood gas data set, reasoning that the device and its’ algorithm would be maximally challenged by ABGs that elicit appreciable shifts in the oxyhemoglobin dissociation curve (OHDC). The OHDC for the Kelman algorithm and the i-STAT algorithm were plotted on the same grid, using Numbers® spreadsheet software (Apple, Inc., Cupertino, CA), providing us with a digital and a diagrammatic comparison of their respective results. Finally, we determined the upper and lower limits of the uncertainty intervals for both the pulse oximeter and the Point-of-Care analyzer and scribed these elements on the single composite image.