I'm guessing from the content she was dealing with ICU psychosis - phenomenon that happens causing hallucinations, temporary irrational behavior, etc. From my reading, the understanding is that occurs due to constant stimulation environment and no distinct sleep/wake cycles. In an ICU it is always daytime, but for some bizarre reason, similar to sundowning in elderly patients, it gets worse at night.
http://www.emedicinehealth.com/script/main/art.asp?articlekey=7769
There are also some physical reasons that are non psychiatric that patients can indeed see visions (temporal lobe epilepsy is known to produce religious visions - such as case of Emily Rose). Dehydration, hypoxia (the general explanation for the visions people see when dying), etc.
Very interesting though - thanks for posting !