Seems like Tom has dosged the bullet with the ICU delirium, biut it is a VERY SERIOUS matter and you need to do what it takes to reuce the chance of it recurring.

There is a good recent survey article in New Scientist which unfortunately you have to pay for:

Delirium in hospital can be a killer for the elderly

Similar content scattered across a few issues of Science Daily, follow links from here:

http://www.sciencedaily.com/releases/2011/12/111212144234.htm

The main point is that it isn't accidental, there are risk factors that hospital staff can do something about.

Clinicians should also take extra care to monitor medications and try not to interrupt patients' sleep patterns. In addition, isolation rooms should have clocks, calendars, and other orienting objects to help avoid sensory deprivation.