Postoperative Delirium Severity and Recovery Correlate with Electroencephalogram Spectral Features

Christian S. Guay, Mohammadmehdi Kafashan, Emma R. Huels, Ying Jiang, Bora Beyoglu, James W. Spencer, Kristin Geczi, Ginika Apakama, Yo El S. Ju, Troy S. Wildes, Michael S. Avidan, Ben Julian A. Palanca

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


BACKGROUND: Delirium is an acute syndrome characterized by inattention, disorganized thinking, and an altered level of consciousness. A reliable biomarker for tracking delirium does not exist, but oscillations in the electroencephalogram (EEG) could address this need. We evaluated whether the frequencies of EEG oscillations are associated with delirium onset, severity, and recovery in the postoperative period. METHODS: Twenty-six adults enrolled in the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES; NCT02241655) study underwent major surgery requiring general anesthesia, and provided longitudinal postoperative EEG recordings for this prespecified substudy. The presence and severity of delirium were evaluated with the confusion assessment method (CAM) or the CAM-intensive care unit. EEG data obtained during awake eyes-open and eyes-closed states yielded relative power in the delta (1-4 Hz), theta (4-8 Hz), and alpha (8-13 Hz) bands. Discriminability for delirium presence was evaluated with c-statistics. To account for correlation among repeated measures within patients, mixed-effects models were generated to assess relationships between: (1) delirium severity and EEG relative power (ordinal), and (2) EEG relative power and time (linear). Slopes of ordinal and linear mixed-effects models are reported as the change in delirium severity score/change in EEG relative power, and the change in EEG relative power/time (days), respectively. Bonferroni correction was applied to confidence intervals (CIs) to account for multiple comparisons. RESULTS: Occipital alpha relative power during eyes-closed states offered moderate discriminability (c-statistic, 0.75; 98% CI, 0.58-0.87), varying inversely with delirium severity (slope, -0.67; 98% CI, -1.36 to -0.01; P =.01) and with severity of inattention (slope, -1.44; 98% CI, -2.30 to -0.58; P =.002). Occipital theta relative power during eyes-open states correlated directly with severity of delirium (slope, 1.28; 98% CI, 0.12-2.44; P =.007), inattention (slope, 2.00; 98% CI, 0.48-3.54; P =.01), and disorganized thinking (slope, 3.15; 98% CI, 0.66-5.65; P =.01). Corresponding frontal EEG measures recapitulated these relationships to varying degrees. Severity of altered level of consciousness correlated with frontal theta relative power during eyes-open states (slope, 11.52; 98% CI, 6.33-16.71; P <.001). Frontal theta relative power during eyes-open states correlated inversely with time (slope, -0.05; 98% CI, -0.12 to -0.04; P =.002). CONCLUSIONS: Presence, severity, and core features of postoperative delirium covary with spectral features of the EEG. The cost and accessibility of EEG facilitate the translation of these findings to future mechanistic and interventional trials.

Original languageEnglish (US)
Pages (from-to)140-151
Number of pages12
JournalAnesthesia and analgesia
Issue number1
StatePublished - Jan 1 2023
Externally publishedYes

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine


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