How Quickly Does Pulmonary Fibrosis Progress?

My 66 year old nephew, who has a hx of heart trouble blue with multiple stents, went into the hospital and after a CT scan, was dx with pneumonia. Two days later, they put him on a vent to help his body to nosy work so hard. Two days later, they repeated the CT scan and said it now showed widespread bilateral fibrosis. Is it really possible to get that bad, that quickly? I am a nurse, and always thought pulmonary fibrosis was a chronic disease that progressed over time.