Can entropy predict neurologic complications after cardiac surgery?

Area of Science:

• Anesthesiology
• Neurology
• Critical Care Medicine

Background:

• Electroencephalography (EEG) is valuable for detecting cerebral ischemia/hypoxia, seizures, and hypnotic effects.
• Entropy-based monitoring (Response Entropy [RE] and State Entropy [SE]) is an EEG derivative used to assess anesthetic depth.

Observation:

• Two patients undergoing urgent coronary artery bypass grafting (CABG) under target-controlled propofol-sufentanil anesthesia experienced abrupt decreases in RE and SE to isoelectric silence.
• These low entropy values persisted intraoperatively, followed by delayed awakening and confirmed nonhemorrhagic temporoparietal cerebral infarctions on CT scans.

Findings:

• Intraoperative isoelectric silence on entropy monitoring during propofol-sufentanil anesthesia correlated with delayed awakening and cerebral infarction in CABG patients.
• Abrupt decreases in RE and SE may serve as an early warning sign for potential neurological damage.

Implications:

• Entropy-based monitoring could enhance neurological outcome prediction in high-risk cardiac surgery patients.
• This suggests a potential role for intraoperative EEG derivatives in guiding anesthetic management to prevent perioperative brain injury.
• Further research is warranted to validate these findings in larger cohorts.