Memory and awareness in anaesthesia.

The 9th International Symposium on Memory and Awareness in Anesthesia (MAA9) was held in Tokyo, Japan on June 20–23, 2014, attracting over 70 delegates fromaround theworld. It was chaired by Jiro Kurata, from the TokyoMedical andDental University, and was jointly sponsored by the British Journal of Anaesthesia to support research activities in the fields of awareness during anaesthesia, neurobiological mechanisms of general anaesthesia, consciousness, andmemory. This topic complements the recently published National Audit Project NAP5 survey of accidental awareness under general anaesthesia conducted in the UK in 2012 and published in the British Journal of Anaesthesia last year. The present British Journal of Anaesthesia special issue on Memory and Awareness in Anaesthesia was planned by Hugh Hemmings, a co-organizer of MAA9, to present the most current findings and views on topics from selected presentations during the meeting, in addition to submissions in response to an open call for papers. All the MAA9 abstracts are also included in this special on-line-only issue. Details of the MAA9 programme can be found at the conference website (http://maa9.umin.jp/). The scope of previous MAA symposia has ranged from the neuroscience of anaesthetic action, memory, and consciousness to the clinical aspects of awareness during anaesthesia. The MAA9 followed this tradition, while emphasizing the clinical aspects: epidemiology, diagnosis, prevention, and treatment of intraoperative awareness, with a conference slogan of ‘Minding the Mind of Subconscious Self’. Although anaesthesiology has devoted tremendous efforts to studies of anaesthetic pharmacology and the mechanisms of anaesthetic-induced unconsciousness, which can be approached in a relatively direct manner through behavioural analyses, it has paid much less attention to subconscious processes of mind. At least part of memory is formed in the subconscious domain of mind, and for this reason could be resistant to clinical ranges of general anaesthetics aimed to produce elimination of conscious behaviour. The MAA9 was programmed to propose that anaesthesiology should now approach the next stage, the care for the subconscious mind. Detection of intraoperative awareness during anaesthesia has historically been a major focus of research and technology development in anaesthesiology. Currently, there are several kinds of anaesthetic depth monitors, in addition to real-time or simulated monitors of anaesthetic concentrations, available in most operating theatres. Behaviour-based standardization of mathematically processed EEG, cortical evoked potentials, or both has attempted to turn ‘probability of awareness’ into an anaesthetic depth index, or a ‘vital sign for consciousness’. In recent years, such indices for anaesthetic depth have been tested for efficacy in detecting intraoperative awareness compared with anaesthetic concentration monitors, which is summarized in the review by Mashour, along with some of the controversial and established aspects of intraoperative awareness. Despite such efforts, titrated administration of anaesthetics, using either an anaesthetic depth or a concentration monitor, has not been successful in decreasing the incidence of intraoperative awareness with recall. No single reliable anaesthetic technique or monitor is yet available to eliminate awareness with recall during general anaesthesia.