Thirty minutes after intubation and initiation of mechanical ventilation,a patient's PₐO₂ = 55 mm Hg and the FɪO₂ = 0.5.To what should the FɪO₂ be set to obtain a PₐO₂ of 80 mm Hg?
A) 0.65
B) 0.75
C) 0.85
D) 0.95

Question

Quizplus · Accepted Answer

To calculate the necessary FɪO₂ level to increase the PₐO₂ from 55 mm Hg to 80 mm Hg, we can use the following formula: 
(PaO₂desired ÷ FɪO₂new) = (PaO₂current ÷ FɪO₂current)
Substituting the known values, we get:
(80 ÷ FɪO₂new) = (55 ÷ 0.5)
Solving for FɪO₂new, we get:
FɪO₂new = (80 ÷ 55) × 0.5 = 0.727
Rounding up to the nearest 0.05 increments, the best choice is 0.75 (B).

Thirty Minutes After Intubation and Initiation of Mechanical Ventilation,a Patient's