A male patient (76-kg IBW) with no history of pulmonary disease is brought to the emergency department for treatment of a drug overdose. He is intubated and placed on mechanical ventila-tion with VC-CMV, f = 12/min, VT = 450 mL

The resulting arterial blood gas values are: pH 7.32, PaCO2 53 mm Hg, and HCO3? 25 mEq/L. The most appropriate action to correct the acid-base disturbance is which of the following?
a. Increase VT to 595 mL.
b. Increase VT to 760 mL.
c. Increase frequency to 16/min.
d. Decrease frequency to 10/min.

ANS: A
Desired VT ??Known PaCO2 ⋅?Known VT / Desired PaCO2
The desired target for VT for this patient is 5-8 mL/kg IBW. Because the set VT of 450 mL is at 5.9 mL/kg, there is room to increase the VT. After calculating the desired VT using the formula, the new volume is at 7.8 mL/kg. A VT of 760 mL would be at 10 mL/kg IBW.