[Investigation of intracranial pressure in intensive care unit patients with delirium assessed by bedside ultrasound]

Abstract

Objective: To explore the changes of intracranial pressure in intensive care unit (ICU) patients during the occurrence and evolution of delirium by using bedside ultrasound to measure the optic nerve sheath diameter (ONSD) to evaluate intracranial pressure.

Methods: A retrospective observational study was conducted. Adult patients who developed delirium during hospitalization in the general ICU of Beihai People's Hospital from October 2020 to November 2021 were enrolled, and patients who did not have ultrasonographic ONSD records within 24 hours after the diagnosis of delirium were excluded. The ONSD measured before delirium was recorded as ONSD₀, the ONSD measured within 24 hours of the onset of delirium recorded as ONSD₁, and the ONSD reexamined after ONSD₁ recorded as ONSD₂. Patients were divided into intracranial hypertension group (ONSD₁ > 5 mm) and normal intracranial pressure group (ONSD₁ ≤ 5 mm) according to the size of ONSD₁. According to the outcome of delirium, the patients were divided into cured, improved, and non-improved groups. The reduction ratio of ONSD₂ to ONSD₁ in the three groups were calculated and compared. Pearson correlation test was used to analyze the correlation between fluid balance and ONSD changes after delirium.

Results: There were 43 patients, including 40 cases in the intracranial hypertension group (the incidence rate was 93.0%), 3 cases in the normal intracranial pressure group, 23 cases were cured, 13 cases were improved, and 7 cases were not improved. In the intracranial hypertension group, 11 cases had ONSD₀ and ONSD₁ records, and ONSD₁ was significantly higher than ONSD₀ [mm: 5.88±0.61 vs. 5.34±0.57, 95% confidence interval (95%CI) -0.85 to -0.23, P = 0.003]. The reduction ratio of ONSD₂ to ONSD₁ in the cured group was significantly higher than that in the improved group and the non-improved group [(12.04±6.20)% vs. (5.68±4.10)%, (0.17±3.96)%; 95%CI were 2.37 to 10.33, 6.41 to 17.31, P values were 0.003 and 0.000, respectively]. The correlation analysis showed that the reduction ratio of ONSD₂ to ONSD₁ was negatively correlated with fluid balance (r = -0.42, 95%CI was -0.66 to -0.10, P = 0.012).

Conclusions: The incidence of intracranial hypertension in ICU delirium patients is high. A more pronounced decrease in intracranial pressure predicts a better delirium outcome. Dynamic ONSD measurement can provide valuable information for the prevention and treatment of delirium.