Diagnostic value of mismatch-negativity and P3a event-related potentials for sepsis-associated encephalopathy in non-sedated patients: a pilot study

BACKGROUND: Although the Confusion Assessment Methods for the Intensive Care Unit (CAM-ICU) is a recommended tool for diagnosing sepsis-associated encephalopathy (SAE), it has several limitations. Mismatch-negativity (MMN) and P3a are components of event-related potentials (ERPs) used with electroencephalography (EEG) and are associated with cerebral function changes in critically ill patients. This study aimed to provide a quantitative, non-invasive method to guide SAE diagnosis in non-sedated patients. METHODS: From January 2022 to March 2023, sepsis patients without sedation were enrolled and assessed via the CAM-ICU, Glasgow Coma Scale (GCS), and ERP under standard procedures. Both MMN and P3a data were collected. The diagnostic value of MMN and P3a was assessed with processed ERP data. RESULTS: Thirty-six patients were included in this study, comprising 19 patients with SAE and 17 patients without SAE (NSAE). MMN and P3a amplitudes decreased, and only FzMMN amplitude significantly decreased in SAE patients (2.03 [1.08, 2.93] mV vs. 3.21 [1.92, 4.34] mV, P=0.040). After median dichotomization, low F3P3a and FzP3a amplitudes were associated with higher CAM-ICU positivity rates and APACHE II scores. Both amplitude in F3P3a (AUC=0.710, 95%CI: 0.527–0.893, P=0.034) and FzP3a (AUC=0.700, 95%CI: 0.519–0.881, P=0.041) exhibited moderate diagnostic efficacy for SAE, while FzMMN amplitude lacks effective diagnostic value. CONCLUSION: In this pilot study, ERP components F3P3a and FzP3a amplitudes demonstrated moderate diagnostic value for SAE. These exploratory findings require confirmation in larger and powered cohorts.