Fig. 4.

A Bland-Altman plot of $\mathrm{S}{\mathrm{a}}_{{\mathrm{O}}_{\mathrm{2}}}$ and $\mathrm{S}{\mathrm{p}}_{\mathrm{O}}{}_{{}_{\mathrm{2}}}$ at the end of a maximal apnea. This figure demonstrates an overestimation of $\mathrm{S}{\mathrm{a}}_{{\mathrm{O}}_{\mathrm{2}}}$ (radial blood draw) by $\mathrm{S}{\mathrm{p}}_{\mathrm{O}}{}_{{}_{\mathrm{2}}}$ (finger pulse-oximetry) at the end of apnea in elite breath-hold divers using data from our previous study (4). Dotted line represents the mean difference (5.3), whereas the dashed lines represent the upper and lower limits of agreement (16.1 and −5.6, respectively). Of note is that the overestimation of $\mathrm{S}{\mathrm{a}}_{{\mathrm{O}}_{\mathrm{2}}}$ by $\mathrm{S}{\mathrm{p}}_{\mathrm{O}}{}_{{}_{\mathrm{2}}}$ is most evident below a $\mathrm{S}{\mathrm{a}}_{{\mathrm{O}}_{\mathrm{2}}}$ of 70%. Each data point represents an individual subject; n = 14.