Risk factors for occurrence of delirium in critically ill patients include: age (OR = 1.04; p < 0.001), age > 65 (OR = 2.62; p = 0.008), dementia (OR = 19.21; p = 0.006), APACHE II score (OR = 1.13; p < 0.001), invasive mechanical ventilation (OR = 3.77; p = 0.001), intubation (OR = 3.68; p = 0.002), re-intubation (OR = 5.43; p = 0.040), surgery (OR = 4, 02; p = 0.003), catheter insertion for resuscitation (OR = 2.76; p = 0.015), patient restraint (OR = 9.50; p < 0.001), CRP level (OR = 1.005; p = 0.009), hypoxia (OR = 2.22; p = 0.043), use of fentanyl (OR = 3.06; p < 0.001) and midazolam (OR = 4.39; p < 0.001).