The sedative and electroencephalographic effects of regional anaesthesia*

✍ Scribed by A. P. Morley; D. C. Chung; A. S. Y. Wong; T. G. Short

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 106 KB
• Volume: 55
• Category: Article
• ISSN: 0003-2409
• DOI: 10.1046/j.1365-2044.2000.01473.x

✦ Synopsis

We studied sedation scores, the processed electroencephalogram and mean arterial pressure pre‐operatively in patients before and after spinal (n = 15) and lumbar epidural (n = 15) anaesthesia. We compared them with changes occurring over time in a control group (n = 15), using the responsiveness component of the Observer Assessment of Alertness and Sedation rating scale. The electroencephalographic variables studied were bispectral index, 95% spectral edge frequency, median frequency and the power distribution between frequency bands α, β, θ and δ. No differences were detected within groups in sedation scores before and after intervention, or between groups at either stage. No between‐group differences were detected in electroencephalographic variables. In the spinal group, spinal anaesthesia caused an increase in bispectral index, 95% spectral edge frequency, median frequency and β frequencies, and a decrease in δ frequencies and mean arterial pressure. The increase in β frequencies is similar to that seen in patients with low plasma concentrations of midazolam and may represent subclinical sedation.