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Towards gas narcosis monitoring in compressed gas diving (PhD Academy Award)
  1. Xavier C Vrijdag
  1. Anaesthesiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
  1. Correspondence to Xavier C Vrijdag, Anaesthesiology, The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand; x.vrijdag{at}

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What did I do?

I aimed to develop an objective and reliable measurement tool to quantify subanaesthetic levels of gas narcosis in scuba divers. I investigated pupillometry, critical flicker fusion frequency and novel quantitative electroencephalogram (EEG) algorithms.

Why did I do it?

Divers venturing underwater, either for work or pleasure, may experience narcotic effects caused by their breathing gases. The onset of narcosis symptoms is expected around 30 m (405 kPa) when breathing air. The principal hazard of gas narcosis is euphoria, overconfidence and loss of judgement. This may cause the diver to become less alert, take extra risks and start a chain of events culminating in a severe diving accident. No early warning signal is available. Therefore, an objective method to detect narcosis could improve diver safety by characterising the related effects of each component in the breathing gas mixture, allowing the diver to make informed choices about gas mix composition and facilitating related research.

How did I do it?

In three studies involving 12 sport divers each, participants were exposed to: (1) 3 low-dose inspired fractions of nitrous oxide (20%, 30% and 40%) blinded, in random order, as a normobaric research surrogate for hyperbaric nitrogen; (2) air and heliox (helium–oxygen mixture) at 284 …

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  • Contributors The manuscript was prepared by XV with contributions from his supervisors.

  • Funding This work has been supported by funding from the Office of Naval Research Global, United States Navy (N62909-18-1-2007).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.