Marino The ICU Book 4e, IE

802 Nervous System Disorders

DELIRIUM

Attention Deficits Difficulty focusing or maintaining attention

(and)

Disordered Thinking Disorganized, illogical, or incoherent responses

(with)

Fluctuating Changes in Behavior Behavioral changes fluctuate over a 24-hour period

Hyperactive Form Patient is agitated

Hypoactive Form* Patient is agitated

*Most common form of delirium in ICU patients.

FIGURE 44.2 The clinical features of delirium

Subtypes The following subtypes of delirium are recognized:

1. Hyperactive delirium is characterized by restless agitation. While this form of delirium is common in alcohol withdrawal, it is rare in hos- pital-acquired delirium , accounting for ≤ 2% of cases (6). 2. Hypoactive delirium is characterized by lethargy and somnolence. This is the most common form of hospital-acquired delirium , and is responsible for 45 – 64% of cases (6). 3. Mixed delirium is characterized by episodes of delirium that alternate between hyperactive and hypoactive forms of the illness. This type of delirium is reported in 6 – 55% of patients with hospital-acquired delirium (6). As indicated, the popular perception of delirium as a state of agitated confusion does not apply to hospital-acquired delirium, where the most