[Risk factors for delirium in intensive care unit and its duration].

Objective: To screen risk factors for delirium and its duration in intensive care unit (ICU) patients.

Methods: 1 200 patients admitted to ICU of the Second Hospital of Shanxi Medical University from May 2017 to May 2019 were enrolled. The gender, age, anesthesia mode, duration of mechanical ventilation and hypoxia, acute physiology and chronic health evaluation II (APACHE II) score, sedative drug use, and length of ICU stay were recorded. The occurrence and duration of ICU delirium were recorded. Multivariate Logistic regression analysis and multiple linear regression analysis were used to analyze the factors with statistical significance differences between the groups for screening the risk factors for delirium and its duration in ICU patients.

Results: 397 of 1 200 patients developed delirium, the incidence of ICU delirium was 33.1%. The duration of delirium in 189 patients (47.6%) was 1.0 day, and the duration of delirium in 397 delirium patients was 2.0 (1.5, 2.5) days. (1) Analysis of risk factors for delirium: univariate analysis showed that there was no significant difference in the incidence of ICU delirium among patients with different genders or ages. The incidence of ICU delirium in patients with duration of mechanical ventilation or hypoxia 4-9 days and ≥ 10 days was higher than that in patients with ≤ 3 days. The incidence of ICU delirium of general anesthesia and internal medicine patients was higher than that of patients with lumbar anesthesia. The incidence of ICU delirium in patients with APACHE II score ≥ 20 was higher than that in patients with ≤ 10 and 11-19. The patients with length of ICU stay > 9 days had a higher ICU delirium incidence than those ≤ 8 days. Increased incidence of ICU delirium in sedative patients was found as compared with those who did not use sedatives. Multivariate Logistic regression analysis showed that APACHE II score [odds ratio (OR) = 5.491, 95% confidence interval (95%CI) was 4.361-6.913, P < 0.001], the length of ICU stay (OR = 2.679, 95%CI was 1.822-3.941, P < 0.001) and the use of sedatives (OR = 2.479, 95%CI was 1.821-3.374, P < 0.001) were risk factors for ICU delirium. (2) Analysis of risk factors of ICU delirium duration: univariate analysis showed that there was no significant difference in ICU delirium duration in patients with different genders or ages. The duration of ICU delirium in patients with duration of mechanical ventilation or hypoxia ≥ 10 days was longer than that in patients with ≤ 3 days and 4-9 days. The duration of ICU delirium in general anesthesia and non-surgical patients was higher than that in patients with spinal anesthesia. The ICU delirium duration in patients with APACHE II score ≥ 20 was longer than that in patients with ≤ 10 and 11-19. The duration of ICU delirium in patients with the length of ICU stay > 9 days was longer than that in patients with ≤ 8 days. The duration of ICU delirium in patients on sedatives was longer than those not taking sedatives. Multiple linear regression analysis showed that the duration of ICU delirium increased by an average of 0.061 days (β = 0.061, 95%CI was 0.032-0.090, P < 0.001) for each additional day of hypoxia (hypoxia duration was divided into three grades of ≤ 3, 4-9 and ≥ 10 days). For every one increase in APACHE II score (APACHE II score was divided into three grades of ≤ 10, 11-19 and ≥ 20), duration of ICU delirium extended an average of 0.058 days (β = 0.058, 95%CI was 0.048-0.068, P < 0.001). ICU delirium duration increased by an average of 0.065 days in patients with length of ICU stay > 9 days as compared with those ≤ 8 days (β = 0.065, 95%CI was 0.056-0.075, P < 0.001). On average, the duration of ICU delirium was prolonged by 0.362 days in patients on sedatives as compared with those who did not use sedatives (β = 0.362, 95%CI was 0.234-0.490, P < 0.001).

Conclusions: APACHE II score, the length of ICU stay and the use of sedatives were common risk factors for ICU delirium and its duration. The hypoxic duration was risk factors for ICU delirium duration.