Delirium in ICU

Delirium in Intensive Care Unit

The acute cerebral dysfunction (delirium) is extremely frequent in the Intensive Care Units patients, ranging from 11% to 80% depending on the populations of critical patients studied, and it's an independent predictive factor of:

- Increase in hospital morbidity and mortality of three times circa;
- Increase in duration of mechanic ventilation and in Intensive Care Unit hospitalization;
- Increase in hospital costs;
- Worsening of long term neurological recovery (dementia induced by Intensive Care Unit)
The typical features of delirium are: quick onset, distraction, fluctuating alteration of the mental state, disorientation, worsening in the night hours.

There are three types of delirium: the hyperactive delirium is characterized by agitation, restlessness, actual risk of invasive devices removal. The hypoactive delirium is characterized by alienation, emotional flattening, apathy, lethargy, responsiveness decrease. A Mixed delirium arises when the patient's symptoms vary between the two patterns described above. The mixed delirium and the hypoactive one are the most frequent in the Intensive Care Units, and they are often misdiagnosed if there isn't a daily monitoring. Few patients of Intensive Care Units (< 5%) have a pure hyperactive delirium.

The evaluation of delirium is an peremptory part of the daily neurological monitoring and it's made up of two stages.

The first stage consists in the evaluation of consciousness level with a validated scale: the Richmond Agitation-Sedation Scale (RASS). The second stage is the evaluation of cognitive functioning; it is impossible to estimate this issue at deep sedation levels (RASS= -4 or -5), because the patient isn't responsive. These levels are defined as coma state; the CAM-ICU cannot be used in these cases and the patient must be described as "not valuable". At more superficial sedation levels (RASS ≥ -3) patients show signs of responsiveness that alloud to evaluate the lucidity of their thoughts and, in case, the presence of delirium.

It must be underlined that to diagnose the actual presence of delirium with DSM-IV criteria it must be present an etiological cause, such as sepsis, cerebral hypoperfusion, hypo-/hyperglycaemia, hypoxya, fever, dyselectrolytemias, withdrawal, hepatic encephalopathy, acidosis/alkalosis, psychoactive substances administration. If these causes aren't present, the acute cerebral dysfunction cannot be defined as delirium.

The international literature makes everyone clearly understand that it's not only important to diagnose the presence/absence of delirium, but also to estimate the duration of delirium: every further day of delirium determines a considerable increase in mortality!

Therefore it's clear that a good Intensive Care Unit provides:

- The prevention of delirium (non pharmacological protocol);
- The monitoring of delirium, at least once every nursing shift
- The immediate resolution of the underlying organic/metabolic causes ;
- The eventual antipsychotic therapy once all the amendable causes are sorted out

Age&Agening 2010 Clegg - Medications to avoid if risk of delirium

ARJCCM 2009 Pisani - Days of delirium and 1 year·mortality in older·ICU patients

CC 2007 Chevrolet - Review on agitation and delirium in ICU

CC 2009 VandenBoogaard - Delirium assessment in ICU and Haloperidol use··

CC 2010 Salluh - Delirium epidemiology in ICU - DECCA study

CCM 2001 Ely - Validation of CAM-ICU for delirium in ICU critically ill patients

CCM 2007 Devlin - Use of ICDSC improves delirium identification

CCM 2009 Lat - The impcat of delirium on clinical outcomes in mechanically ventilated patients

CCM 2009 Pisani - Benzodiazepine and opioid correlates with duration of delirium in ICU

CCM 2010 Luetz - Different assessment tools for ICU delirium

CHEST 2007 Pun - Delirium diagnosis

ICM 2007 Devlin - Delirium assessment in critically ill patients