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Up to 85% of patients who are treated in the ICU experience ICU delirium, an often overlooked cognitive dysfunction that occurs when the brain is subjected to a critical illness and subsequent medical treatment. Patients with ICU delirium appear lethargic, confused, or may be unresponsive to loved ones, nurses, and doctors—these symptoms frequently go unnoticed in busy hospital settings. Although ICU delirium can sometimes be benign, emerging research has demonstrated that it’s often a dangerous situation; it’s been associated with a higher risk for long-term neurocognitive impairment in ICU survivors. In addition, ICU delirium appears to be an independent predictor of increased hospital stay and of a threefold increased risk of death within 6 months.

Although ICU delirium typically resolves in most patients, some may experience permanent brain dysfunction in the form of an acquired dementia-like illness. This can affect memory and executive function, which significantly interferes with quality of life. Most strikingly, ICU delirium may be reduced in some patients by identifying it early and changing certain risky medications in critically ill patients or modifying other risk factors.

Spotting Patient Risk Factors

Advanced age and severe sepsis may increase patients’ risk for ICU delirium. When sepsis occurs, the body’s organs don’t receive sufficient blood flow and nutrients, which in turn can cause delirium. Other risk factors include the unintended excessive use of sedatives and narcotics. Although these drugs are typically safe for short-term use in the general population, using them for too long and in too high a dose when managing patients with a critical illness increases the risk of delirium. Sleep deprivation is also very likely to play a role in ICU delirium; the absence of sleep creates a catabolic condition that we believe adversely affects the brain over time and increases the risk for developing delirium. Patients in the ICU often obtain only 1 or 2 hours of “real” sleep per day. Even though they may appear to be unconscious, it’s important to recognize that sedative use can actually suppress sleep. A relatively new sedative—dexmedetomidine—was recently found in two double-blind randomized controlled trials to be associated with less acute brain dysfunction (delirium and coma) than benzodiazepines, but it should be noted that further research is needed to more clearly determine its role in ICU delirium.

Monitoring & Measuring Are Key

The Confusion Assessment Method for the ICU (CAM-ICU) is one simple and quick tool that has been developed to measure and monitor ICU delirium. The CAM-ICU criteria determine the presence of inattention in patients—inattention is the pivotal feature of delirium. Physicians and nurses can use this tool in less than 60 seconds to detect delirium with about 95% accuracy (as measured against a 30-minute neuropsychiatric examination). Once ICU-delirium is identified, the ICU team must review the treatment strategy, electrolyte levels, and fluid status; identify the presence of new or ongoing infections; and then follow a delirium management algorithm. This should include correcting sleep-wake cycles (lights on during the day, lights out and quiet and asleep at night), removing restraints and practicing early mobilization, and giving patients their eye glasses and hearing aids, if need be, so that they can be reoriented to their surroundings. Additionally, offending drugs, such as sedatives, should be removed from the treatment protocol.

The duration of delirium is one of the strongest predictors of death and long-term cognitive problems, which is why current guidelines recommend routine monitoring of all ICU patients daily. Delirium monitoring should be a priority, and the ICU team must work collaboratively to resolve delirium by reducing modifiable risk factors.

E. Wesley Ely, MD, MPH has indicated to Physician’s Weekly that he has received grants for clinical research and educational activities from Lilly, Pfizer, Hospira, and Aspect Medical, and GlaxoSmithKline. He has also served as an advisor or consultant to Lilly, Hospira, and Healthways.