Related Experiment Videos
Sedation during spinal anesthesia.
J E Pollock1, J M Neal, S S Liu
1Department of Anesthesiology, Virginia Mason Medical Center, Seattle, Washington, USA.
Anesthesiology
|September 2, 2000
Summary
Spinal anesthesia causes progressive sedation, as measured by Observer's Assessment of Alertness/Sedation Scale (OAA/S) scores, which may involve delayed mechanisms. The Bispectral Index (BIS) monitor was not sensitive to this sedation in a blinded study.
Area of Science:
- Anesthesiology
- Neuroscience
Background:
- Central neuraxial anesthesia is known to reduce the need for other anesthetic agents.
- This effect is hypothesized to result from reduced stimulation of the reticular activating system.
Purpose of the Study:
- To quantify the sedative effects of spinal anesthesia using the Bispectral Index (BIS) monitor.
- To investigate the potential mechanisms of sedation associated with spinal anesthesia.
Main Methods:
- A two-part study involving unmedicated volunteers.
- Part I: Non-randomized pilot study with BIS and Observer's Assessment of Alertness/Sedation Scale (OAA/S) monitoring before and after spinal anesthesia.
- Part II: Randomized, double-blind, placebo-controlled study with BIS and OAA/S monitoring in volunteers receiving spinal anesthesia or placebo.
Main Results:
- Part I showed progressive changes in BIS scores after spinal anesthesia.
- Part II revealed significant decreases in OAA/S and self-sedation scores in the spinal anesthesia group compared to placebo.
- BIS scores did not significantly differ between the spinal anesthesia and placebo groups in Part II.
Conclusions:
- Spinal anesthesia induces progressive sedation, confirmed by OAA/S and self-sedation scores, independent of block height.
- A delayed sedation effect observed at 60 minutes suggests potential secondary mechanisms, possibly related to local anesthetic spread.
- The BIS monitor demonstrated limited sensitivity in measuring spinal anesthesia-induced sedation in the blinded study setting.