An 18-year-old, 5'6", 125 lb female patient was admitted to the hospital 2 days ago for spinal meningitis

She developed sepsis and suffered hypercapnic respiratory failure. The patient was intubated and placed on volume-controlled continuous mandatory ventilation (VC-CMV), respiratory frequen-cy (f) 12 breaths/min, tidal volume (VT) 600 mL, positive end-expiratory pressure (PEEP) 5 cm H2O, fractional inspired oxygen (FIO2) 0.40. Twenty-four hours later, the patient's oxygen re-quirements have dramatically increased and her lung compliance has dramatically dropped, while her chest X-ray showed development of bilateral fluffy infiltrates. The most appropriate actions to take include which of the following?
a. Keep VT the same, increase f to 25 breaths/min, increase PEEP to 12 cm H2O.
b. Decrease VT to 250 mL, increase f to 15 breaths/min, increase PEEP to 15 cm H2O.
c. Increase VT to 550 mL, decrease f to 8 breaths/min, increase PEEP to 10 cm H2O.
d. Decrease VT to 400 mL, decrease f to 8 breaths/min, decrease PEEP to 3 cm H2O.

ANS: B
During the acute phase of the disease, adequate ventilation should be provided using a tidal volume (VT) in the range of 4-6 mL/kg while plateau pressure (Pplateau) is maintained at <30 cm H2O with rates of 15-25 breaths/min. For this patient the VT range should be between 244 and 488 mL with a rate between 15 and 25 breaths/min. Answer "B" fits into this guideline.