Transient electroencephalographic alpha power loss during maintenance of general anaesthesia

Hight, Darren F; Gaskell, Amy L.; Kreuzer, Matthias; Voss, Logan J.; García, Paul S.; Sleigh, Jamie W. (2019). Transient electroencephalographic alpha power loss during maintenance of general anaesthesia. British journal of anaesthesia, 122(5), pp. 635-642. Elsevier 10.1016/j.bja.2018.11.029

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Background: EEG activity in the extended alpha frequency range (7-17 Hz) during maintenance of general anaesthesia is primarily determined by effect-site concentrations of the hypnotic and analgesic drugs used. Intermittent alpha loss during surgery, unexplained by changes in anaesthetic or opioid concentrations, could represent arousal of the cortex as a result of increased surgical stimulation. Methods: A generalised linear model was fitted to alpha power recorded from patients undergoing general anaesthesia from induction until waking using three explanatory variables: age-adjusted volatile anaesthetic effect-site concentration, and estimated effect-site propofol and opioid concentrations. Model residuals were decomposed into uncorrelated white noise and a fluctuating auto-correlated trend. Deviations of this local trend were classified as 'unexpected alpha dropout events'. To investigate whether these alpha dropouts might be explained by the effect of noxious stimulation, we related their occurrence to whether a patient was undergoing surgery involving the body cavity or not. Results: Alpha power dropouts occurred in 73 of the 237 patients included in the final analysis (31%, median amplitude of -3.5 dB, duration=103 s). They showed a bimodal or broadly skewed distribution, being more probable soon after initial incision (32%), dropping to around 10% at 1 h, and then again increasing to >30% in operations lasting >3 h. Multivariate analysis showed that alpha dropouts were significantly associated with body cavity surgery (P=0.003) and with longer operations (P<0.001). Conclusions: A loss of alpha power, unexplained by changes in anaesthetic or opioid concentrations, is suggestive of thalamocortical depolarisation induced by body cavity noxious stimuli, and could provide a measure of nociception during surgery.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Intensive Care, Emergency Medicine and Anaesthesiology (DINA) > Clinic and Policlinic for Anaesthesiology and Pain Therapy

UniBE Contributor:

Hight, Darren

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0007-0912

Publisher:

Elsevier

Language:

English

Submitter:

Jeannie Wurz

Date Deposited:

25 Jun 2019 16:02

Last Modified:

24 Oct 2019 07:47

Publisher DOI:

10.1016/j.bja.2018.11.029

PubMed ID:

30915994

BORIS DOI:

10.7892/boris.130330

URI:

https://boris.unibe.ch/id/eprint/130330

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