Figure 4.

Model simulations and measured data for six patients selected to represent typical cases. Model fitted simulations (curves) and measured data (crosses) describing (i) inspired oxygen fraction (FiO₂) versus arterial oxygen saturation (SaO₂) and (ii) FiO₂ versus the partial pressure of oxygen in arterial blood (PaO₂)/FiO₂ ratio. (a) Normal subject [14], (b) cardiac incompensation patient [14], (c) gynaecological laparotomy patient [14], (d) cardiac surgery patient [15], (e) intensive care patient [14], and (f) previously unpublished intensive care data. Curves, parameter values and fitting residuals (root mean square (RMS)) for the 'effective shunt' model (dashed lines, 'effective shunt' parameter) and for the two-parameter model (solid lines, shunt and ΔPO₂ parameters). Thick lines, range of FiO₂ giving a SaO₂ of 92–98%.