Until recently I had never heard of hospital-acquired delirium before. From UCLA Health:
“(T)he type of confusion you describe isn’t unusual in older adults who have been hospitalized. Sometimes referred to as hospital-acquired delirium, it’s a temporary but severe form of mental impairment that affects up to one-third of patients over the age of 70, particularly those undergoing surgery or those in intensive care. The condition is marked by periods of confused thinking, jumbled memory, difficulty understanding speech, agitation, disorientation and even hallucinations.
“The duration of hospital-acquired delirium can be as brief as a few hours or…can continue for several days.”
Bredemarket 