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

Stephan Lang, Robert Herold, Alexander Kraft, Volker Harth, Alexandra M.

PLoS ONE 13(12):e0207648.

Spiroergometric measurements of persons who require oxygen insufflation due to illness
can be performed under conditions of increased inspiratory oxygen concentration (FIO2).
This increase in FIO2, however, often leads to errors in the calculation of oxygen consumption
(V_ O2). These inconsistencies are due to the application of the Haldane Transformation
(HT), an otherwise indispensable correction factor in the calculation of V_ O2 that becomes
inaccurate at higher FIO2 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 FIO2 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 (FIO2 =
20.9%), as well as at FIO2 = 40% and 80%. When compared with the predicted values of
V_ O2, 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 FIO2 of 40%. At FIO2
concentrations of 80%, however, the V_ O2 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 FIO2 allows a reliable
evaluation of stress tests in patients requiring high doses of supplemental oxygen.