A 60-Year-Old Woman Is Brought to the Hospital for Fever

A 60-year-old woman is brought to the hospital for fever, chills, productive cough, and worsening shortness of breath.  These symptoms began 3 days ago but have worsened over the last 24 hours.  Her other medical problems include type 2 diabetes, hypertension, and psoriatic arthritis.  Her medications include methotrexate, metformin, glyburide, lisinopril, and hydrochlorothiazide.  She has a 20-pack-year smoking history.
The patient's temperature is 39.3 C (102.7 F) , blood pressure is 110/70 mm Hg, pulse is 112/min, and respirations are 22/min.  Oxygen saturation is 90% on room air.  Examination shows mild respiratory discomfort with crackles over the right lower lung field.  The remainder of the examination shows no significant abnormalities.
The patient is admitted to the hospital and started on intravenous antibiotics and normal saline at 150 mL/hr.  Over the next 12 hours, she develops worsening shortness of breath and hypotension requiring transfer to the intensive care unit.  Her blood pressure is 80/50 mm Hg, respirations are 36/min, and oxygen saturation is 82% on 100% oxygen.  She is intubated emergently.  Repeat chest x-ray, in the image below, shows diffuse bilateral airspace disease.  Laboratory results are as follows: pH 7.38, PaCO₂ 39 mm Hg, and PaO₂ 61 mm Hg on FIO₂ of 100%.

Which of the following is most likely to improve this patient's prognosis?

A) High-frequency ventilation
B) Low positive end-expiratory pressure
C) Low tidal volume ventilation
D) Maintenance of low PaCO₂
E) Use of inotropic agents with invasive cardiac output monitoring