Risk factors associated with delirium in a general ICU: role of S-100 protein

Introduction

Delirium is an increasing complication of the ICU patient. We estimated the incidence of delirium using the Confusion Assessment Methods for the Intensive Care Unit (CAM-ICU) in a cohort of general ICU patients. We also investigated the value of S-100 protein to reflect this clinical condition.

Methods

Adult consecutive patients admitted to the ICU for more than 72 hours were entered in the study. The CAM-ICU was performed at admission and subsequently twice a day, by medical staff. Clinical data were evaluated in a univariate and multivariate analysis with STATA/10. S-100 protein in patients who experienced delirium was compared with patients not experiencing delirium.

Results

Twenty-two patients entered into the study. Delirium occurred in 36.4%. The risk of delirium was independently associated with sepsis and use of vasoactive drugs during the ICU stay, but not with age, sex, SAPS II, benzodiazepine or opiate use (Figure 1). Delirium was linked to a longer ICU stay (16.25 vs 6.28 days) and mechanical ventilation period (20.4 vs 8.4 days). Patients that experienced delirium showed a higher level of S-100 protein (0.19 ± 0.06 μg/l) than control (0.05 ± 0.03 μg/l) (Figure 1).

Figure 1

(abstract P513)

Conclusion

In our study, delirium increases the ICU stay and duration of mechanical ventilation. Perturbation of the thalamic filter associated with the use of vasoactive drugs with anticolinergic properties and hypotension seems to be a predisposing factor for the incidence of delirium. Delirium represents an early symptom of cerebral dysfunction, and an increased level of S-100 protein can be an early marker of brain injury in sepsis-associated encephalopathy.