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Effects of etomidate administration on cerebral collateral flow
S C Robertson1, P Brown, C M Loftus
1Division of Neurosurgery, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City 52242, USA.
Neurosurgery
|August 8, 1998
Summary
Etomidate did not increase cerebral blood flow (CBF) to collateral-dependent tissue (CDT) during ischemia in dogs. Instead, it reduced CBF, suggesting its neuroprotective effects are not related to augmenting blood flow.
Area of Science:
- Neuroscience
- Anesthesiology
- Cerebrovascular Research
Background:
- Selective vasodilation of collateral vessels can augment blood flow to collateral-dependent tissue (CDT) after middle cerebral artery occlusion.
- Etomidate, a nonbarbiturate anesthetic, is known for its anesthetic and neuroprotective properties.
- The effect of etomidate on collateral cerebral vessels remains largely unknown.
Purpose of the Study:
- To investigate whether etomidate selectively augments cerebral blood flow (CBF) to CDT during ischemia.
- To determine if this augmentation contributes to etomidate's neuroprotective mechanisms.
Main Methods:
- 14 dogs underwent a left craniotomy under halothane anesthesia.
- Middle cerebral artery occlusion was performed, and CDT was measured using a "shadow flow" technique.
- Etomidate infusion was administered, and CBF, vascular pressures, and vascular resistance were measured, including during induced hypotension.
Main Results:
- Etomidate infusion significantly reduced CBF in all brain regions, including CDT (53.7% reduction).
- Normal CBF reduction was at least 63.4% during etomidate infusion.
- Hypotension further reduced blood flow to CDT (additional 42.7%) and normal cerebrum (at least 22.7%), with increased vascular resistance observed.
Conclusions:
- Etomidate does not appear to augment collateral or global CBF during ischemia.
- The neuroprotective effects of etomidate are likely mediated through mechanisms other than increased blood flow.