Which of the Following Patients Has the Most Serious Problem

Short Answer

Which of the following patients has the most serious problem with the adequacy of oxygenation?
$\begin{array}{lll}\text { Patient }&\mathrm{FIO}_{2}&\underline{\mathrm{PaO}_{2}}\\\text { A. } & 0.70 & 90 \\\text { B. } & 0.40 & 95 \\\text { C. } & 1.00 & 85 \\\text { D. } & 0.28 & 65\end{array}$