Delirium in critically ill patients: incidence, risk factors and outcomes

Abstract

Objective: To determine the incidence, and evaluate the risk factors and outcomes of delirium in general Intensive Care Unit (ICU).

Design: Prospective cross-sectional observational study.

Setting: Teaching hospital in Kuala Lumpur, Malaysia.

Patients and participants: Patients ages of 18 and above admitted for more than 24 hours in general ICU were recruited into the study.

Measurements and results:The demographic data, predisposing and precipitating factors, and environmental factors were collected. Confusional Assessment Method (CAM-ICU) was done daily to assess delirium, when the patient had a sedation score of above Richmond Agitation and Sedation Scale (RASS) -3. Patients were followed up till discharged from ICU. Length of mechanical ventilation and length of ICU stay were recorded.

A total of 139 patients were recruited with overall incidence of delirium was 42%. Among patients who had delirium, 68% were of hypoactive delirium, 25% of mixed delirium and 7% were hyperactive delirium. The significant predisposing risk factors for developing delirium were age, higher Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, visual or hearing impairment, smoking, renal impairment, diabetes, and hypertension. The factors detected precipitating delirium were sepsis, use of vasopressors, renal replacement therapies, and acute respiratory distress syndrome (ARDS). The presence of catheters, higher Sequential Organ Failure Assessment (SOFA) scores, and abnormal urea and bilirubin levels further significantly increased risk of delirium. Environmental conditions increasing the risk of delirium included absence of daylight exposure and visible clocks, and use of physical restraints. As a result of delirium, patients had longer length of mechanical ventilation and ICU stay.Conclusions: Recognizing predisposing factors and optimizing the modifiable risk factors will improve the length of mechanical ventilation and ICU stay.

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