Nearly half of non-ventilated patients in intensive care units experience delirium

May 31 2005

A study published today in the open access journal Critical Care reveals for the first time that nearly half of non-ventilated patients in intensive care units (ICU) experience delirium, which is also an independent predictor of longer hospital stay. It was previously though that this was only an issue for mechanically-ventilated ICU patients.

Researchers recommend regular monitoring of all ICU patients to prevent and treat delirium, which is both harmful to patients and costly to hospitals.

Delirium occurs in 60 to 80% of mechanically ventilated patients and is independently associated with more deaths, longer stays in hospital and higher costs: every day spent in delirium is associated with a 10% higher risk of death and decreased long-term cognitive function.

E.Wesley Ely, from Vanderbilt University Medical Centre, USA, and colleagues followed a total of 261 individuals who were patients in the medical centre's intensive care unit for longer than 24 hours and did not require invasive mechanical ventilation. The patients were followed from their admission to either death or discharge from the hospital. Delirium, or a state of changing mental status, inattention and disorganised thinking, was monitored by the nursing staff and assessed using the Confusion Assessment Method for the Intensive Care Unit every 12 hours.

The results show that 48% of patients experienced delirium. This group of patients had a higher mortality rate: 19% of them died, compared to just 6% of patients who hadn't experienced delirium. Patients who experienced delirium at least once also had a 29% greater risk of remaining in the ICU and a 41% greater risk of remaining in the hospital. Overall, delirium was associated with a one day longer stay in the ICU and two days longer in the hospital.

"Considering the rising overall resource use and economic burden of caring for critically ill patients, our finding that ICU delirium is an independent predictor of longer stay in the hospital is of particular relevance" write the authors.

These results call for routine delirium monitoring of all ventilated and non-ventilated patients in ICU's, a recommendation that is in line with the Society of Critical Care Medicine's Clinical Practice Guidelines.

The authors' findings "should stimulate future research in the field of delirium prevention and treatment". They add that if tools to stratify the severity of delirium were available, doctors could be better able to "recognize patients who are at the highest risk for negative outcomes". This would enable prevention and early treatment of delirium, avoiding debilitating after- effects in patients and unnecessary strains on hospital resources.