Motoric subtypes of delirium in mechanically ventilated surgical and trauma intensive care unit patients

Acute brain dysfunction or delirium occurs in the majority of mechanically ventilated (MV) medical intensive care unit (ICU) patients and is associated with increased mortality. Unfortunately delirium often goes undiagnosed as health care providers fail to recognize in particular the hypoactive form that is characterized by depressed consciousness without the positive symptoms such as agitation. Recently, clinical tools have been developed that help to diagnose delirium and determine the subtypes. Their use, however, has not been reported in surgical and trauma patients. The objective of this study was to identify the prevalence of the motoric subtypes of delirium in surgical and trauma ICU patients.

Adult surgical and trauma ICU patients requiring MV longer than 24 h were prospectively evaluated for arousal and delirium using well validated instruments. Sedation and delirium were assessed using the Richmond Agitation Sedation Scale (RASS) and the Confusion Assessment Method in the ICU (CAM-ICU), respectively. Patients were monitored for delirium for a maximum of 10[Symbol: see text]days or until ICU discharge.

A total of 100 ICU patients (46 surgical and 54 trauma) were enrolled in this study. Three patients were excluded from the final analysis because they stayed persistently comatose prior to their death.

Prevalence of delirium was 70% for the entire study population with 73% surgical and 67% trauma ICU patients having delirium. Evaluation of the subtypes of delirium revealed that in surgical and trauma patients, hypoactive delirium (64% and 60%, respectively) was significantly more prevalent than the mixed (9% and 6%) and the pure hyperactive delirium (0% and 1%).

The prevalence of the hypoactive or "quiet" subtype of delirium in surgical and trauma ICU patients appears similar to that of previously published data in medical ICU patients. In the absence of active monitoring with a validated clinical instrument (CAM-ICU), however, this subtype of delirium goes undiagnosed and the prevalence of delirium in surgical and trauma ICU patients remains greatly underestimated.