Professor Simon Mitchell

MB ChB, PhD, DipDHM, DipOccMed, FUHM, FANZCA, Head of Department, Department of Anaesthesiology, School of Medicine, University of Auckland

Simon is a physician and scientist with specialist training in diving medicine and anaesthesiology.  He is widely published with over 130 papers or book chapters. He co-authored the 5th edition of “Diving and Subaquatic Medicine” and has 2 chapters on decompression illness in the most recent edition of Bennett and Elliott. He has twice been Vice President of the Undersea and Hyperbaric Medicine Society (USA) and in 2010 received the society’s Behnke Award for contributions to the science of diving and hyperbaric medicine. In the past Simon was a naval diving medical officer and medical director of the Wesley Centre for Hyperbaric Medicine in Brisbane. He now works as a consultant anaesthetist at Auckland City Hospital, and Professor in Anaesthesiology at the University of Auckland. He provides on-call cover for diving and hyperbaric emergencies at the North Shore Hospital Hyperbaric Unit in Auckland.


Simon’s diving career has included more than 6000 dives spanning sport, scientific, commercial, and military diving. He was recently a lead member of teams that were the first to dive and identify 3 deep wrecks of high historical significance in Australia and New Zealand. At the time of one of these dives (2002) the 180m depth represented the deepest wreck dive ever undertaken. He was elected to Fellowship of the Explorers’ Club of New York in 2006, and was the DAN Rolex Diver of the Year in 2015.

The complex business of staying safe in technical diving
The complex business of staying safe in technical diving

The use of technical diving methods (and particularly the use of rebreathers) for deep diving is associated with many recognised hazards. Not surprisingly, there are many examples of related accidents. I have been involved in the investigation of many of these through links to police, coroners courts, medico-legal cases, and through personal contact from victims or their relatives. In this presentation I will take you through some illustrative cases and discuss what we can learn from them. Recurring themes that will arise include mistakes at the human-machine interface in the use of rebreathers and behavioural phenomena such as the “normalisation of deviance” and “corrupted motivation”. I will discuss the seemingly random nature of sporadic serious decompression sickness in deep diving, and the implications for diving practice. Finally, I will propose some “survival tips”, some already well-known and widely accepted in our community, and some (such as the use of checklists) that are more controversial. The evidence for incorporation of properly designed checklists into our practice continues to accumulate, and I will briefly review this.

Hypoxia: insights into a silent killer. 

When we use mixed gases for deep diving, and / or rebreathers, we almost inevitably create opportunities for mistakes that might lead to us inspiring a gas that contain insufficient oxygen to maintain normal body oxygenation. Examples include operation of a rebreather with the oxygen cylinder turned off, or mistakenly using an hypoxic bottom gas during shallow decompression on open circuit. The result of such mistakes is progressive reduction of oxygen levels in the blood (hypoxia). Hypoxia is an insidious condition. It often gives little warning of onset, particularly if there are other distractions. Unlike hypercapnia, which usually produces unpleasant symptoms, a diver can easily pass through a stage of confusion and lapse into unconsciousness with little or no sense that anything is wrong. We have recently been conducting experiments in which human subjects are intentionally rendered very hypoxic whilst trying to perform a mental task, and the video records of these events are educational viewing for divers. In this presentation we will discuss how hypoxia can occur in diving, and how failure to recognize its onset is common. We will illustrate these principles with video and results of our recent experiments. Finally, we will discuss the safety and usefulness of intentional "dry hypoxia experiences" that have occasionally been advocated for divers, and why we don't think these are a good idea. 


Suncourt Hotel & Conference Centre, Lake Taupo


Brent McFadden

TEL: 0274344874 



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