A male patient (83-kg IBW) is intubated and ventilated with…

A male patient (83-kg IBW) is intubated and ventilated with PC-CMV, f = 12/min, set PIP = 28 cm H2O, resulting in a VT of 430 mL. The ABG results on this setting are: pH 7.35, PaCO2 45 mm Hg, and HCO3- 23 mEq/L. Forty-eight hours later on the same settings, the ABG results are: pH 7.54, PaCO2 27 mm Hg, and HCO3- 21 mEq/L with an exhaled VT of 800 mL. The most appropriate action at this time is which of the following?