Correlations Between Quantitative EEG Parameters and Cortical Blood Flow in Patients Undergoing Extracorporeal Membrane Oxygenation With and Without Encephalopathy.

Purpose: The neurologic examination of patients undergoing extracorporeal membrane oxygenation (ECMO) is crucial for evaluating irreversible encephalopathy but is often obscured by sedation or neuromuscular blockade. Noninvasive neuromonitoring modalities including diffuse correlation spectroscopy and EEG measure cerebral perfusion and neuronal function, respectively. We hypothesized that encephalopathic ECMO patients with greater degree of irreversible cerebral injury demonstrate less correlation between electrographic activity and cerebral perfusion than those whose encephalopathy is attributable to medications.
Methods: We performed a prospective observational study of adults undergoing ECMO who underwent simultaneous continuous EEG and diffuse correlation spectroscopy monitoring. (Alpha + beta)/delta ratio and alpha/delta Rartio derived from quantitative EEG analysis were correlated with frontal cortical blood flow index. Patients who awakened and followed commands during sedation pauses were included in group 1, whereas patients who could not follow commands for most neuromonitoring were placed in group 2. (Alpha + beta)/delta ratio-blood flow index and ADR-BFI correlations were compared between the groups.
Results: Ten patients (five in each group) underwent 39 concomitant continuous EEG and diffuse correlation spectroscopy monitoring sessions. Four patients (80%) in each group received some form of analgosedation during neuromonitoring. (Alpha + beta)/delta ratio-blood flow index correlation was significantly lower in group 2 than group 1 (left: 0.05 vs. 0.52, P = 0.03; right: -0.12 vs. 0.39, P = 0.04). Group 2 ADR-BFI correlation was lower only over the right hemisphere (-0.06 vs. 0.47, P = 0.04).
Conclusions: Correlation between (alpha + beta)/delta ratio and blood flow index were decreased in encephalopathic ECMO patients compared with awake ones, regardless of the analgosedation use. The combined use of EEG and diffuse correlation spectroscopy may have utility in monitoring cerebral function in ECMO patients.
Competing Interests: I. R. Khan reports grants from the National Institute of Neurologic Disorders and Stroke, National Heart, Lung, and Blood Institute, and the Department of Defense; G. Schifitto report grants from the National Institute of Neurologic Disorders and Stroke; D. R. Busch reports grants from The Hartwell Foundation, National Institute of Neurologic Disorders and Stroke, and National Institute of Biomedical Imaging and Bioengineering. D. R. Busch has patents on aspects of DCS technologies. These patents are not licensed and produce no revenue. D. R. Busch has equity interest in NFOSYS, a startup seeking to commercialize minimally invasive DCS tools, which currently has no sales and no revenue; R. Choe reports grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases; and R. K. Maddox reports grants from the National Institute on Deafness and Other Communication Disorders, all during the conduct of this study. I. Gosev received consulting and personal fees from Abbott, ABIOMED, and Zimmer Biomet Holdings, outside the scope of this work. The remaining authors have no funding or conflicts of interest to disclose.
(Copyright © 2023 by the American Clinical Neurophysiology Society.)