Chest
Volume 132, Issue 2, August 2007, Pages 624-636
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Recent Advances in Chest Medicine
The Importance of Diagnosing and Managing ICU Delirium

https://doi.org/10.1378/chest.06-1795Get rights and content

ICU delirium represents a form of brain dysfunction that in many cohorts has been diagnosed in 60 to 85% of patients receiving mechanical ventilation. This organ dysfunction is grossly underrecognized because a majority of patients have hypoactive or “quiet” delirium characterized by “negative” symptoms (eg, inattention and a flat affect) not alarming the treating team. Hyperactive delirium, formerly called ICU psychosis, stands out because of symptoms such as agitation that may cause harm to self or staff, but is actually rare relative to hypoactive delirium and associated with a better prognosis. Delirium is often incorrectly thought to be transient and of little consequence. After adjusting for numerous covariates, delirium is a strong, independent predictor of prolonged length of stay, reintubation, higher mortality, and cost of care. Expanded work on patient safety and recommendations by professional societies have established the importance of delirium monitoring and recommended it as standard practice in ICUs all over the world. This evidence-based review for physicians, nurses, respiratory therapists, and pharmacists will outline why it is imperative that patients be routinely monitored for delirium. This review will discuss modifiable risk factors for delirium, such as metabolic disturbances or potent sedative and analgesic medications. Attention to mitigating risk factors, along with recommended pharmacologic approaches such as antipsychotic medications, may provide resolution of delirium in some patients, while others will persist with refractory brain dysfunction and long-term cognitive impairment following critical illness.

Section snippets

Why Should We Monitor for Delirium?

For many years, the critical care community has focused on assessing, preventing, and reversing multiorgan dysfunction syndrome. However, the brain has been subjected to relatively little formal study until recently. ICU patients, especially older persons, are among the most vulnerable hospitalized patients for the development of delirium. Studies234567 have found that delirium develops in 20 to 50% of lower-severity ICU patients or those not receiving mechanical ventilation, and in 60 to 80%

What Is Delirium?

Delirium is defined by the Diagnostic and Statistical Manual of Mental Disorders34 as a disturbance of consciousness with inattention accompanied by a change in cognition or perceptual disturbance that develops over a short period (hours to days) and fluctuates over time. Although there are many hypothesized pathophysiologic mechanisms involved in the development of delirium, most are thought related to imbalances in neurotransmitters that modulate cognition, behavior, and mood. Varied terms

How Do We Monitor for Delirium?

The Society of Critical Care Medicine (SCCM) guidelines47 recommend monitoring delirium routinely in patients receiving mechanical ventilation. There are currently two validated tools for monitoring delirium in ICU patients: the Intensive Care Delirium Screening Checklist48 and the Confusion Assessment Method for the ICU (CAM-ICU).47 The Intensive Care Delirium Screening Checklist (Table 1) is an eight-item checklist with a sensitivity of 99% and specificity of 64% and interrater reliability of

Risk Factors/Etiology: What Are the Modifiable Risk Factors?

One key strategy to prevent or diminish delirium is to identify and modify risk factors that lead to delirium. Inouye et al5455 developed a predictive model for delirium in the elderly non-ICU patients that classified risk factors into two categories: predisposing (baseline vulnerability) and precipitating (hospital related or iatrogenic).55 Numerous risk factors have been identified in non-ICU populations754555657 that fall into these categories, and ICU patients have an average of 11 ± 4

Nonpharmacologic Prevention and Treatment

In the non-ICU setting, risk factor modification has resulted in a 40% relative reduction in the development of delirium.64 Modifications include repeated reorientation of patients, repetitive provision of cognitively stimulating activities for the patients, nonpharmacologic sleep protocol, early mobilization, range-of-motion exercises, timely removal of catheters and physical restraints, use of eye glasses and magnifying lenses, hearing aids and earwax disimpaction, adequate hydration, use of

Conclusions

Although delirium research in critical care is rapidly maturing, the weight of evidence already demonstrates that critical care clinicians cannot afford to ignore this form of organ dysfunction in our patients (Table 5). If we are to be comprehensive in our approach to monitoring and managing organ dysfunction, the brain should be a very active component of our daily discussion at the bedside in the ICU. This article has outlined key reasons to “tip” delirium onto the physician's “radar screen”

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    Dr. Ely was supported by National Institutes of Health grants RO1 AG 072701A1 and AG 01023–01A1 and the VA Merit Review Clinical Science Research and Development, the Measuring the Incidence and Determining Risk Factors for Neuropsychological Dysfunction in ICU Survivors study.

    Ms. Pun has received honoraria from Hospira, Inc. and Cardinal Health and serves as a consultant on research project for Hospira, Inc. Dr. Ely has received grant support and honoraria from Hospira, Pfizer, and Eli Lilly.

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