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Intra-operative electroencephalogram frontal alpha-band spectral analysis and postoperative delirium in cardiac
Céline Khalifa1, Cédric Lenoir, Annie Robert
1From the Department of Anaesthesiology, Cliniques universitaires Saint-Luc, Université catholique de Louvain (UCLouvain) (CK, CW, DK, MM), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCLouvain) (CK, AR, CW, DK, SM, GA, MM), Institute of Neuroscience (IoNS), Université catholique de Louvain (UCLouvain) (CK, CL, CW, AI, AM, MM), Department of Epidemiology and Biostatistics, Université catholique de Louvain (UCLouvain) (AR), Department of Cardiothoracic and Vascular Surgery, Cliniques universitaires Saint-Luc, Université catholique de Louvain (UCLouvain) (SM, GA), Department of Neurology, Cliniques universitaires Saint-Luc, Université catholique de Louvain (UCLouvain), Brussels (AI), Department of Anaesthesia and Intensive Care Medicine, Liège University Hospital (VB) and Anaesthesia and Peri-operative Neuroscience Laboratory, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium (VB).
Background:
Postoperative delirium (POD) remains a frequent complication after cardiac surgery, with pre-operative cognitive status being one of the main predisposing factors. However, performing complete pre-operative neuropsychological testing is challenging. The magnitude of frontal electroencephalographic (EEG) α oscillations during general anaesthesia has been related to pre-operative cognition and could constitute a functional marker for brain vulnerability.
Objective:
We hypothesised that features of intra-operative α-band activity could predict the occurrence of POD.
Design:
Single-centre prospective observational study.
Setting:
University hospital, from 15 May 2019 to 15 December 2021.
Patients:
Adult patients undergoing elective cardiac surgery.
Main Outcome Measures:
Pre-operative cognitive status was assessed by neuropsychological tests and scored as a global z score. A 5-min EEG recording was obtained 30 min after induction of anaesthesia. Anaesthesia was maintained with sevoflurane. Power and peak frequency in the α-band were extracted from the frequency spectra. POD was assessed using the Confusion Assessment Method for Intensive Care Unit, the Confusion Assessment Method and a chart review.
Results:
Sixty-five (29.5%) of 220 patients developed POD. Delirious patients were significantly older with median [IQR] ages of 74 [64 to 79] years vs. 67 [59 to 74] years; P < 0.001) and had lower pre-operative cognitive z scores (-0.52 ± 1.14 vs. 0.21 ± 0.84; P < 0.001). Mean α power (-14.03 ± 4.61 dB vs. -11.59 ± 3.37 dB; P < 0.001) and maximum α power (-11.36 ± 5.28 dB vs. -8.85 ± 3.90 dB; P < 0.001) were significantly lower in delirious patients. Intra-operative mean α power was significantly associated with the probability of developing POD (adjusted odds ratio, 0.88; 95% confidence interval (CI), 0.81 to 0.96; P = 0.007), independently of age and only whenever cognitive status was not considered.
Conclusion:
A lower intra-operative frontal α-band power is associated with a higher incidence of POD after cardiac surgery. Intra-operative measures of α power could constitute a means of identifying patients at risk of this complication.
Trial Registration:
NCT03706989.
