Delirium in ICU patients a predictor of mortality

Apr 16 2004

There are an estimated 6,000 intensive care units in the United States caring for approximately 55,000 patients daily.

Between 60 percent to 80 percent of these patients develop a brain dysfunction known as delirium, which according to a group of physicians at Vanderbilt Medical Center is an independent predictor of mortality.

In Wednesday’s issue of The Journal of the American Medical Association, E. Wesley Ely, M.D., associate professor of Medicine and Research, and his team provided the first documented study to include daily measurements of delirium in the Intensive Care Unit, pointing to longer hospital stays and a three-fold increase in death.

“The dilemma in critical care is that people often develop brain dysfunction or delirium in the ICU setting which is thought to be of no real importance to survival or long-term quality of life,” Ely said. “Frankly, it’s been overlooked by medical teams for years and is simply called ‘ICU psychosis.’”

“Five years ago, we began studying delirium in the ICU at Vanderbilt, after realizing that older people are more frequently going to ICUs and the added risk of developing brain dysfunction was present.”

The JAMA piece titled “Delirium as a Predictor of Mortality in Mechanically-Ventilated Patients in the Intensive Care Unit” is a culmination of the work to date, Ely said.

“We have found that using the most robust statistical methods available to adjust for the severity of illness, age, coma and drugs used for sedation, the development of delirium presents the patients with a 300 percent increased likelihood of dying by six months as compared to similar patients who didn’t develop delirium,” Ely said.

“All of this work is ultimately leading us down the path of delirium prevention and treatment,” he said. “Right now there are no data from randomized trials proving the best treatment. Secondly, delirium is grossly under-recognized so even if we knew how to treat it, nurses and doctors miss it most of the time.”

Ely and his team have been responsible for developing protocols for identifying delirium as well as measuring and validating a patient’s stage of brain dysfunction.

These methods of measuring and validating delirium were recently documented in two other JAMA manuscripts. They have also been translated into seven languages and are recommended as a standard of care by the Society for Critical Care Medicine for all patients treated with mechanical ventilation.

Thousands of institutions worldwide have contracted Ely’s team to implement delirium monitoring, and many more have likely downloaded the materials from their Web site at www.icudelirium.org.

For several decades, medical teams have known that organ failures in ICUs were frequent and they have been studying how to prevent the kidneys and lungs from shutting down during a critical illness and what treatment is appropriate.

“But since we didn’t recognize that brain failure was a problem, those studies haven’t been done yet for the brain. It is ironic because the brain is arguably the most important organ of all. We are currently planning two trials and are already conducting another interventional trial.”

Currently, there are pharmaceutical and pharmacological interventions as well as interventions directed toward changing the practice patterns of physicians and nurses.

“The next stage is to learn what percentage of patients with delirium can have the complications either prevented or treated in order to lessen morbidity and/or mortality associated with critical illness,” he said. “That’s where we are in the overall scope of our discovery process.”

Ely said the first problem with delirium is the mortality rate. The second is cost. The estimated cost of treating delirium in the ICU ranges from $4 billion to more than $20 billion nationwide. Third, Ely and his team assert, is the impact the duration and severity of delirium will likely have on the neuropsychological deficits of these patients.

“These deficits are the types that prevent people from going back to work, helping their children with their homework and from finding their car in the parking lot,” Ely said. “In general, it prevents them from obtaining the type of quality of life they had prior to their critical illness. These are problems seen in not only the elderly, but in younger patients as well.

“With nearly 40,000 patients estimated to develop delirium daily in the United States alone, you can imagine the magnitude of this problem worldwide,” he said.

Delirium in ICU patients has many potental causes, Ely said, some of them overlapping and combining in some patients. They include: underlying dementia, sleep deprivation, the patient receiving psychoactive drugs, metabolic abnormalities and periods of hypoxemia, disregulation of blood flow, and inflammatory disturbances due to sepsis. Treatments may address any of these potential causes that are modifiable in the ICU setting, he said.