Postoperative delirium screening: Delirium observation screening scale versus single-channel EEG after cardiac surgery

Introduction / Purpose: Delirium in elderly patients following cardiac surgery is associated with increased complications and prolonged hospitalization. Early identification of delirium in high-risk patients is essential and is supported by an ERAS 1B recommendation. Although various screening tools are available, hypoactive delirium is frequently missed by nurse-reported assessments. In this study, we compared single-channel electroencephalography (SC-EEG) with the nurse-reported Delirium Observation Screening Scale (DOSS) for detecting postoperative delirium and assessing its impact on length of hospital stay after cardiac surgery.

Materials and Method: In a prospective, quasi-experimental study conducted at the nursing ward, we compared DOSS screening (442 patients) and SC-EEG screening (462 patients) to identify postoperative delirium in cardiac surgery patients aged over 70 years. Definitive delirium diagnosis was made according to DSM-5 criteria, and analyses were adjusted for baseline differences using multivariable regression models. 

Findings
The SC-EEG group demonstrated a higher delirium detection rate (20%) compared
to the DOSS group (14%) (p = 0.016) as determined with segmented linear regression. In unadjusted analyses, delirious patients identified via SC-EEG had a significantly shorter median hospital stay (p = 0.002). However, multivariable analysis showed that pneumonia and extended cardiopulmonary bypass time, rather than the screening method, were responsible for this difference (p = 0.54). In all patients, the SC-EEG-screened group had a 0.11-day shorter hospital stay (95% CI:-0.18 to -0.04) compared to the DOSS group (p = 0.002).

Discussion / Conclusion
This new screening instrument SC-EEG screening showed an improved delirium detection rate following cardiac surgery. Although, it did not led to a reduction in length of stay among patients diagnosed with delirium, a modest reduction in length of stay for all patients with and without delirium in the SC-EEG cohort was found. These findings hightllight the potential value of objective delirium screening. The impact for clinical relevance should be further explored.