SO WHAT CAUSES HOSPITAL DELIRIUM?

POST-OPERATIVE or ICU delirium is most common among the over 60s who already have some kind of cognitive impairment, but it can affect younger people as well.

‘It happens more often than people think,’ says Dawne Garrett, professional lead for older people and dementia care at the Royal College of Nursing. ‘It is marked by usually reversible memory disturbances, confusion and hallucinations.’

Some people may become incoherent, others paranoid. The symptoms tend to develop in the days immediately following an operation and may fluctuate in severity depending on the time of day, often deteriorating at night.

People with existing lung or heart conditions may be at greater risk as they may have less oxygen flow to the brain and the type of surgery also makes a difference. ‘Those undergoing major surgery — particularly cardiac surgery — are at higher risk,’ says Dr William Harrop-Griffiths, chair of the clinical quality and research board at the Royal College of Anaesthetists. Why is unclear, but may relate to the anaesthetic.

A study in the U.S. by researchers at Johns Hopkins Hospital found post-operative delirium was far more common among those who had a general anaesthetic than those who had a local. One theory is that a general anaesthetic leads to more surgery-induced stress inside brain cells.

Post-op delirium is associated with longer hospitalisation, loss of function and higher mortality, according to a study in the Journal of the American Geriatric Society.

‘Almost everyone who suffers from postoperative delirium will get better, but it can take days or weeks,’ says Dr HarropGriffiths. ‘There is no specific treatment.’