Spiroergometric measurements under increased inspiratory oxygen concentration (FIO2)—Putting the Haldane transformation to the test

Spiroergometric measurements of persons who require oxygen insufflation due to illness can be performed under conditions of increased inspiratory oxygen concentration (FIO(2)). This increase in FIO(2), however, often leads to errors in the calculation of oxygen consumption ([Image: see text] ). These inconsistencies are due to the application of the Haldane Transformation (HT), an otherwise indispensable correction factor in the calculation of [Image: see text] that becomes inaccurate at higher FIO(2) concentrations. A possible solution to this problem could be the use of the ‘Eschenbacher transformation’ (ET) as an alternative correction factor. This study examines the concentration of FIO(2) at which the HT and the ET are valid, providing plausible data of oxygen consumption corresponding to the wattage achieved during cycle ergometry. Ten healthy volunteers underwent spiroergometric testing under standard conditions (FIO(2) = 20.9%), as well as at FIO(2) = 40% and 80%. When compared with the predicted values of [Image: see text] , as calculated according to Wasserman et al. (2012), the data obtained show that both the HT and ET are valid under normal conditions and at an increased FIO(2) of 40%. At FIO(2) concentrations of 80%, however, the [Image: see text] values provided by the HT begin to lose plausibility, whereas the ET continues to provide credible results. We conclude that the use of the ET in place of the HT in spiroergometric measurements with increased FIO(2) allows a reliable evaluation of stress tests in patients requiring high doses of supplemental oxygen.