A 26-year-old woman with a past history of seizure disorder is admitted to the medical ICU with status epilepticus. Due to continued seizures, she is placed in a barbiturate coma. As pa of suppoive measures, she is intubated, placed on a mechanical ventilator, and given IV fluids through a central line. She remains stable overnight. In the morning, however, the respiratory therapist repos that she has had excessive mucopurulent secretions throughout the night and that her peak and plateau airway pressures have risen 20 cm. She is febrile with a temperature of 100.2degF the next morning. CXR is shown.An impoant step in management of this patient would be