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A marked decrease in bispectral index with elevation of suppression ratio by cervical haematoma reducing cerebral
N Umegaki1, K Hirota, M Kitayama
1Department of Anesthesiology, School of Medicine, University of Hirosaki, Hirosaki, Japan.
Summary
Bispectral index (BIS) monitoring detected cerebral ischemia during anesthesia for aortic aneurysm repair. This EEG monitor may offer a simple way to identify brain ischemia during complex surgeries.
Area of Science:
- Anesthesiology
- Neuroscience
- Critical Care Medicine
Background:
- Bispectral index (BIS) monitoring is used to assess depth of anesthesia and sedation.
- Cerebral ischemia is a critical complication during major vascular surgeries, particularly those involving aortic manipulation.
Observation:
- A patient undergoing ruptured abdominal aortic aneurysm repair under ketamine anesthesia experienced significant BIS reductions and increased suppression ratio (SR) correlating with hemodynamic instability (hypotension) and later, a large cervical hematoma.
- The cervical hematoma, potentially compressing the carotid artery, was associated with further BIS/SR changes, which improved after surgical relief.
Findings:
- BIS monitoring, alongside the suppression ratio (SR), reflected cerebral ischemia during both hypotensive and non-hypotensive events.
- Hemodynamic improvements and surgical intervention (relief incision) positively impacted BIS and SR values, suggesting a correlation with cerebral perfusion.
Implications:
- This case highlights the potential utility of BIS monitoring as a non-invasive tool for detecting intraoperative cerebral ischemia.
- BIS monitoring may provide early warnings for neurological compromise in high-risk surgical patients, guiding timely interventions.