Complex older patients represent about half of all acute public hospital admissions in Australia. People with dementia are a classic example of complex older patients, and have been identified to have higher rates of hospital-acquired complications. Complications contribute to poorer patient outcomes, and increase length of stay and cost to hospitals. The care for older people with dementia is complex, and this has been attributed to: their cognitive response to being hospitalised; their limited ability to self-care; and lack of nursing engagement with the family caregiver. Registered nurses can offer simultaneous assessment and intervention to prevent or mitigate hospital-acquired complications. However, it is known that when demand for nursing care exceeds supply, care is prioritised according to acute medical need. Consequently some basic but essential nursing care activities such as patient mobility, communication, skin care, hydration and nutrition are implicitly rationed. This paper offers a theoretical proposition of ‘Failure to Maintain’ as a conceptual framework to indicate implicit care rationing by nurses. Care rationing contributes to functional and cognitive decline of complex older patients, which then contributes to higher rates of hospital acquired complications. Four key hospital acquired complications: pressure injuries, pneumonia, urinary tract infections and delirium are proposed as measurable indicators of ‘Failure to Maintain’. Hospital focus on throughput constrains nurses to privilege predictable, solvable and medically-related procedures and processes that will lead to efficient discharge over patient mobility, communication, skin care, hydration and nutrition. This privileging, also known as implicit rationing, is theoretically and physiologically associated with a rise in the incidence of complications such as pressure injuries, pneumonia, urinary tract infection, and delirium. Complex older patients, including those with dementia, are at higher risk of the complications, therefore should have higher delivery of prophylactic intervention (ie have higher care needs). ‘Failure to Maintain’ offers a conceptual framework that is inclusive of, and sensitive to, this vulnerable population. Implicit rationing is occurring and it likely contributes to functional and cognitive decline in complex older patients and hospital-acquired complications. However, the lack of patient functional ability data at admission and discharge for hospitalised patients, and lack of usable ward and hospital level nurse staffing and workload data makes it difficult to monitor, understand and improve quality of care. Current research in the fields of acute geriatrics and nursing work environments show promise through enabling multidisciplinary team communication, and facilitating clinical autonomy to provide patient focussed care, and avoid ‘Failing to Maintain’. The research field of acute geriatrics can understand and act on the risk modification role of nurses, including controlling for nurse staffing and work environment variables in intervention studies. The research field of nurse sensitive outcomes should incorporate the different profile of complex older patients, by including age brackets and functional ability as variables in their studies. Clinically, nursing work environments can be designed to recognise the different profile of complex older patients by adapting practices to privilege mobility, hydration, nutrition, skin care and communication in the midst of acute care interventions.