A 86-year-old woman is admitted to the elderly care ward. She has dementia and her 4AT on admission is 2 (no delirium). On day 3, the nursing staff note she is 'a bit more confused' but do not formally reassess. On day 5, she is found pulling at her catheter, distressed, and unresponsive to verbal reassurance. A 4AT is now 10. What system failure does this scenario MOST clearly illustrate?