By James E. McFeely, MD
Medical Director, Critical Care Units, Alta Bates Summit Medical Center, Berkeley, CA
Dr. McFeely reports no financial relationships relevant to this field of study.
The Society of Critical Care Medicine (SCCM) published a clinical practice guideline for the management of pain, agitation, and delirium in adult patients in the intensive care unit (ICU) as part of an overall program aimed at liberating patients from the ventilator (and from the ICU in general).1
Delirium is a syndrome characterized by the acute onset of central nervous system dysfunction identified by the following four features: 1) a change or fluctuation in baseline mental status, 2) inattention, and either 3) disorganized thinking or 4) an altered level of consciousness. Delirium affects 60-80% of those on mechanical ventilation and a lesser number of ICU patients who are not ventilated. Delirium is an important predictor of negative outcomes in ICU patients. Even after adjusting for age, severity of illness, coma, and other relevant covariates, patients with delirium have a three-fold higher mortality rate at 6 and 12 months, have a longer hospital length of stay, and may develop long-term cognitive impairment resembling a dementia-like state.2 Many studies have shown that ICU delirium cannot be accurately diagnosed unless a valid and reliable assessment tool is used. Yet the use of such tools is still limited in clinical practice, as is the use of a safe and effective strategy to ensure patient comfort while maintaining a light level of sedation.3
At least four risk factors have been associated with the development of delirium in the ICU: pre-existing dementia, hypertension, alcoholism, and severity of illness. Other factors that may play a role include age, neurologic illness (such as coma), and use of medications (sedatives, antipsychotics, analgesics). Delirium develops rapidly in the ICU, often over hours to days, and is commonly reversible. There are three subtypes of delirium: hyperactive, hypoactive, and mixed. Most ICU patients have a mixed type.
ASSESSMENT
The most commonly recommended bedside tool for identifying delirium in the ICU is the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). The CAM-ICU tool is adapted for use at the bedside to identify the four diagnostic features of delirium. It has been shown to be a valid instrument in the ICU patient population, is easily and quickly applied at the bedside, and has good inter-rater reliability.4
The CAM-ICU tool consists of four tests (see Table 1). For the diagnosis of delirium to be made, the patient must have both elements 1 and 2 and at least element 3 or 4. The tool requires use of the Richmond Agitation-Sedation Scale (RASS), an objective measure of level of consciousness (LOC). Other LOC scales can be used and translated into the RASS for this purpose. This tool should be applied to all ICU patients at least once a shift, or as often as every 2 hours for a patient with fluctuating mental status. Patients deemed CAM-ICU positive are considered to have delirium.
Table 1: CAM-ICU Diagnostic Criteria (Must have features 1 and 2, and either 3 or 4) |
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1. Patient’s mental status is different than his/her baseline OR fluctuation in mental status in the previous 24 hrs identified based on an objective rating scale (such as RASS) or a previous delirium assessment |
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2. Inattention as evidenced by inability to identify letters or pictures when asked to do so |
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3. Altered level of consciousness (any RASS score other than 0) |
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4. Disorganized thinking evidenced by inability to answer questions |
PREVENTION
Delirium occurs at some point in most ICU patients. There are some actions that can be taken that will help minimize the likelihood of development of delirium and can help speed its resolution (see Table 2). Most of these are non-pharmacologic and involve environment of care. They include maintaining a normal sleep wake cycle and intellectual engagement between the patient and his/her family and care team.
Table 2: Tips To Prevent the Development of Delirium |
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Repeated reorientation of patients |
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Minimization of unnecessary noise/stimuli |
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Cognitively stimulate patients multiple times daily |
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A non-pharmacologic sleep protocol |
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Use of a scheduled pain management |
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Early mobilization |
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Regular assessment of the need for catheters and physical and chemical restraints |
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Use of eye glasses and magnifying lenses, hearing aids |
TREATMENT
Once a patient is identified as having delirium, initiation of a management protocol is appropriate (see Tables 3 and 4). Many non-pharmacologic interventions can both prevent and treat delirium. Pharmacologic therapy remains controversial. There are no data indicating the use of haloperidol reduces the duration of delirium in ICU patients. Atypical antipsychotics may reduce delirium duration.5 Development of torsades is always a concern. No recommendations were made in the most recent guidelines for use of any class of antipsychotics to treat delirium. Dexmedetomidine is preferred over benzodiazepines as a sedative for treatment of non-alcohol or benzodiazepine withdrawal delirium. It is also preferred over benzodiazepines for ventilated patients with delirium.6,7
Table 3: Treatment of Delirium (CAM-ICU Positive) Patients |
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1. Consider differential diagnosis (sepsis, medications, CHF, etc). |
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2. Consider removing drugs that promote delirium (metoclopramide, H2 blockers, promethazine, diphenhydramine, steroids, etc) |
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3. Begin non-pharmacologic protocol (See Table 4) |
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4. If patient is agitated (RASS +2 to +4), assess and treat pain if present. If not, use minimum (non-benzodiazepine) sedative needed for comfort. Consider typical or atypical antipsychotics. |
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5. If patient is calm (RASS 0 to +1), assure pain control. Consider typical or atypical antipsychotics. |
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6. If patient is sedate (RASS -1 to -3), reassess sedation goal or perform spontaneous awakening trial. |
Table 4: Non-Pharmacological Protocol |
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Orientation Provide visual and hearing aids Encourage communication and reorient patient repetitively Have familiar objects from patient’s home in the room Attempt consistency in nursing staff Allow television during day with daily news Non-verbal music |
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Environment Sleep hygiene: Lights off at night, on during day. Sleep aids (zolpidem, mirtazipine) Control excess noise (staff, equipment, visitors) at night Ambulate or mobilize patient early and often |
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Clinical parameters Maintain systolic blood pressure > 90 mmHg Maintain oxygen saturations > 90% Treat underlying metabolic derangements and infections |
Ultimately, identification and treatment of delirium is part of the overall goal of early liberation from the ventilator and the ICU in general. Incorporating the preventive measures listed here and routine use of a validated assessment tool such as CAM-ICU will minimize development of delirium, as well as allow early initiation of pharmacologic and non-pharmacologic treatments when it does occur. Vanderbilt University has developed an excellent website (icudelirium.org) that provides resources and educational materials for delirium assessment. There you will find a training manual, worksheets, pocket cards for bedside providers, and patient education materials, as well as information on the other elements of the liberation bundle. More information on delirium and additional free tools to facilitate implementation of the guidelines in your facility can be found at iculiberation.org.
REFERENCES
- Barr J, et al. Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit. Crit Care Med 2013;41:263-306.
- Pandharipande P, et al. Prevalence and risk factors for development of delirium in surgical and trauma intensive care unit patients. J Trauma 2008;65:34-41.
- Tanios MA, et al. Perceived barriers to the use of sedation protocols and daily sedation interruption: A multidisciplinary survey. J Crit Care 2009;24:66-73.
- Neto AS, et al. Delirium screening in critically ill patients: A systematic review and meta-analysis. Crit Care Med2012;40:1946-1951.
- Devlin JW, et al. Efficacy and safety of quetiapine in critically ill patients with delirium: A prospective, multicenter, randomized, double-blind, placebo-controlled pilot study. Crit Care Med 2010;38:419-427.
- Riker RR, et al. SEDCOM (Safety and Efficacy of Dexmedetomidine Compared With Midazolam) study group: Dexmedetomidine vs midazolam for sedation of critically ill patients: A randomized trial. JAMA 2009;301:489-499.
- Jakob SM, et al, Dexmedetomidine for Long-Term Sedation Investigators. Dexmedetomidine vs midazolam or propofol for sedation during prolonged mechanical ventilation: Two randomized controlled trials. JAMA 2012; 307:1151-1160.
A review of the latest Society of Critical Care Medicine clinical practice guidelines.
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