Dealing with ICU Delirium
Abstract & Commentary
By David J. Pierson, Editor, Professor, Pulmonary and Critical Care Medicine, Harborview Medical Center, University of Washington. Dr. Pierson reports no financial relationships relevant to this field of study.
This article originally appeared in the March 2007 issue of Critical Care Alert. It was peer reviewed by William Thompson, MD. Dr. Thompson is Staff Pulmonologist, VA Medical Center; Associate Professor of Medicine, University of Washington. Dr. Thompson reports no financial relationships relevant to this field of study.
Synopsis: Delirium occurred in about one-third of patients in this study of a mixed medical-surgical ICU population. It was more frequent in more seriously ill patients, and also in those with hypertension, alcoholism, and the effects of sedative and analgesic drugs.
Source: Ouimet S, et al. Incidence, risk factors and consequences of ICU delirium. Intensive Care Med. 2007;33:66-73.
Ouimet and colleagues at Maisonneuve-Rosemont Hospital in Montreal studied 820 consecutive patients admitted to their mixed medical-surgical ICU to determine the incidence of delirium, factors associated with it, and its clinical consequences. The patients were adults who stayed in the ICU more than 24 hours and survived for at least one day. The mean APACHE II score on admission was 16.5, and 79% of the patients were mechanically ventilated. Delirium was assessed daily using the Intensive Care Delirium Screening Checklist (ICDSC), as previously reported by the same group1 and as summarized in Table 1. Patients were considered to have delirium if the score on the 8-point assessment screen was 4 or higher.
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After patients who remained comatose throughout their ICU stay (n = 56) were excluded, delirium occurred in 243 of 764 patients (31.8%), during a mean of 5.7 ± 7 days of data collection per patient. Patients who developed delirium had an ICDSC score of 4 or higher for a mean of 38% of their ICU stay, and 10% of them remained delirious at ICU discharge.
Comparing patients with delirium with those who did not, initial APACHE scores were higher (mean 18 vs 14, respectively; P < 0.0001), but there were no differences in age, sex, or diagnosis, according to the ICDSC. Delirium occurred with equal frequency in medical and surgical patients, and was not more frequent in those with previous neurologic illness. However, it was statistically more frequent in patients with hypertension (odd ratio, 1.88, 95% confidence interval, 1.3-2.6) and alcoholism (OR 2.03, 95%; CI, 1.26-3.25). Delirium was more likely in patients who received sedatives and analgesics, when used to induce coma (OR 3.2, 95%; CI, 1.5-6.8) for procedures, but not when these drugs were used in other circumstances. Patients who developed delirium while in the ICU experienced higher ICU mortality (19.7% vs 10.3%) and overall hospital mortality (26.7% vs 21.4%), as well as longer average stays in both the ICU (11.5 vs 4.4 days) and in the hospital (18.2 vs 13.2 days).
Commentary
Evidence is accumulating that delirium in ICU patients is an important and detrimental phenomenon. A number of studies have found associations between the development of delirium and increased morbidity and mortality, as well as increased lengths of stay in both the ICU and the hospital.2 It stands to reason that sicker patients, and those with longer ICU stays, would be more likely to develop delirium — just as they are more likely to develop nosocomial infections and dysfunction in other organ systems — but multivariate analyses in several studies have documented that the adverse effects of delirium persist when these things are accounted for. Thus the prevention, prompt diagnosis, and treatment of delirium in the ICU should be prominent in the clinician's mind during the management of patients' primary illnesses.
Two assessment schemes are available for diagnosing and monitoring delirium: the ICDSC, as used in the present study,1 and the Confusion Assessment Method for the ICU (CAM-ICU), introduced by Ely and colleagues.3 The incidence of delirium among patients in the ICU in different studies, using these techniques for diagnosis, has ranged from about 10%, to more than 80%, likely reflecting differences in severity of illness, case mix, and management, in addition to any differences between the methods themselves. The incidence of 32% in the present study, which excluded relatively few patients and included a broad mix of medical and surgical ICU patients, seems reasonable, considering all the variables in published reports. In any event, ICU delirium is clearly both common and important, making its recognition and management high priority for all critical care clinicians.
Several other important points are brought out by the Ouimet study and its accompanying editorial. ICU delirium occurs in both "hyperactive" and "hypoactive" forms. While the former is easier to recognize and poses the obvious threats of unintended extubation and dislodgement of vascular lines, studies have shown that delirium in patients lying motionless in bed is also associated with adverse outcomes. Delirium should not be treated with sedatives and narcotics. These agents can mask its manifestations but they do not treat the underlying disorder and, in fact, may make it worse. The current treatment of choice is haloperidol.
Table 2, adapted in part from the editorial by Polderman,2 lists steps clinicians can take to reduce the likelihood that their patients will develop delirium in the ICU.
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While few would argue with the importance of preventing a phenomenon so strongly associated with adverse patient outcomes, at present there is little evidence that treating delirium, once it is recognized, improves those outcomes. Common sense tells us that treatment should help, but well-designed studies of this important aspect of ICU management are sorely needed.
References
1. Bergeron N, et al. Intensive care delirium screening checklist: Evaluation of a new screening tool. Intensive Care Med. 2001;27:859-864.
2. Polderman KH. Screening methods for delirium: Don't get confused! Intensive Care Med. 2007;33:3-5.
3. Ely EW, et al. Delirium in mechanically ventilated patients: Validity and reliability of the confusion assessment method for the intensive care unit (CAM-ICU). JAMA. 2001;286:2703-2710.
Delirium occurred in about one-third of patients in this study of a mixed medical-surgical ICU population. It was more frequent in more seriously ill patients, and also in those with hypertension, alcoholism, and the effects of sedative and analgesic drugs.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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