Sedative and Analgesic Medications: Risk Factors for Delirium and Sleep Disturbances in the Critically Ill
Section snippets
Delirium: prevalence and subtypes
The prevalence of delirium in medical ICU cohort studies has been reported as 20% [19], 70% [20], or 80% [17] depending on the severity of illness and the delirium detection instrument used. Similarly, delirium is seen in approximately 70% of mechanically ventilated trauma and surgical ICU patients [21]. Its incidence is likely to increase in future years as older persons more frequently receive ICU care. Unfortunately, delirium remains unrecognized by the clinician in as many as 66% to 84% of
Prognostic significance of delirium
In non-ICU populations, the development of delirium in the hospital is associated with an in-hospital mortality rate of 25% to 33%, a prolonged hospital stay, and three times the likelihood of discharge to a nursing home [25], [26], [27]. In a three-site study of non-ICU medical patients, delirium was found to be an independent predictor of the combined outcome of death or nursing home placement [28]. McCusker and colleagues [29] reported an adjusted hazard of dying of 2.11 associated with the
Delirium: pathophysiology
The mechanisms of ICU delirium remain a promising area of study and likely overlap with those leading to long-term cognitive impairment. Long-term cognitive impairment refers to the development of dementia-like symptoms in patients after surviving their critical illness. This has been shown to occur in more than 30% of patients after mechanical ventilation for acute respiratory distress syndrome (ARDS), even a year after their ICU admission [9], [36]. From a neuroscience perspective, delirium
Risk factors for delirium
Although numerous risk factors for the development of delirium have been identified in non-ICU cohorts [25], only a few studies have examined these in the ICU population. Patients who are highly vulnerable to delirium may develop the disorder after only minor physiologic stressors, whereas those with low baseline vulnerability require a more noxious insult to become delirious [46]. It is possible to stratify patients into risk groups depending on the number of risk factors present [22], [46],
Summary
Sedatives and analgesics are routinely used in critically ill patients, although they have the potential for side effects, such as delirium and sleep architecture disruption. Although it should be emphasized that these medications are extremely important in providing patient comfort, health care professionals must also strive to achieve the right balance of sedative and analgesic administration through greater focus on reducing unnecessary or overzealous use. Ongoing clinical trials should help
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P. Pandharipande is a recipient of the Foundation of Anesthesia Education and Research's Mentored Research Grant. E.W. Ely is the Associate Director of Research for the Veterans Administration Tennessee Valley Geriatric Research and Education Clinical Center. He is a recipient of the Paul Beeson Faculty Scholar Award from the Alliance for Aging Research as well as a recipient of a K23 from the National Institutes of Health (grant AG01023-01A1).