When his fever spiked, he thought someone was setting him on fire. When orderlies slid him into an MRI, he thought he was being fed into an oven. Frequent catheter changes seemed like sexual abuse. Dialysis? He thought someone was taking blood out of a dead woman’s body and injecting it into his veins.The horrifying, violent hallucinations plagued David Jones, now 39, during a six-week stay in the intensive care unit at Chicago’s Northwestern Memorial Hospital — and for months after he was discharged. He thought he was going crazy and felt very alone.He wasn’t.Recognizing the prevalence of the problem, doctors and nurses across the country are now pushing an ambitious campaign to change practices in intensive care units to reduce cases of “ICU delirium” — a sudden and intense confusion that can include hallucinations, delusions, and paranoia.Anywhere from a third to more than 80 percent of ICU patients suffer from delirium during their hospital stay. And one-quarter of all ICU patients suffer from post-traumatic stress disorder once they leave, a rate that’s comparable to PTSD diagnoses among combat veterans and rape victims. Patients with ICU delirium are less likely to survive and more likely to suffer long-term cognitive damage if they do.