Linassi F, Zanatta P, Tellaroli P et al.
British Journal of Anaesthesia. 2018;121(1):198-209. doi: 10.1016/j.bja.2018.02.019
Aim of Study
Determine the overall incidence of connected consciousness during general anaesthesia (GA) as demonstrated by a positive isolated forearm technique (IFT) result
Measure the effect of two different factors; route of anaesthetic and the use of anaesthetic brain monitoring (ABM), on the incidence of connected consciousness during GA
Methodology
Meta analysis of research published in English between 1977-2017
Excludes all paediatric studies and studies measuring connected consciousness by alternative methods to IFT
A total of 22 papers met the inclusion criteria
Results
Total positive IFT – 31.2% (total explicit recall 6.2%)
Positive IFT by GA method:
- Inhaled – 47.3% total (25.5% during maintenance)
- IV – 50.5% total (45.3% during maintenance)
Positive IFT by ABM monitoring
- ABM guided – 64% total (57% during maintenance)
- Non-ABM guided – 48% total (19% during maintenance)
Discussion
Similar incidence of total IFT responses at any time during GA in all four domains
Patients more likely to experience connected consciousness during IV GA, or GA guided by ABM
ABM has been shown in other research to have marked limitations. Possible that ABM falsely reassures clinicians of the depth of their patient’s levels of sedation.
These trends in positive IFT responses were closely correlated when compared to the incidence of explicit recall
Limitations
High heterogeneity between studies, exposing inconsistencies in data collection and interpretation
Paired with a small amount of literature, this led to wide ranging confidence intervals
Confounding factors such as age and weight impacted results and were not controlled for
Conclusion
IV GA and ABM monitored patients are more likely to maintain connected consciousness during anaesthesia
Still a challenge to actively monitor depth of anaesthesia
Further research is required to optimise treatment and reduce the potential psychological sequelae associated with connective consciousness whilst minimising the toxic effects of GA
Summary by Dr T Leahy. Journal Club Meeting 26 September 2019.
Image from http://www.nationalauditprojects.co.uk
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