The Oxford Hyperbaric Group

The beginnings of this work followed a visit to Berkeley in 1963, when Brian Smith was struck by the fact that CF₄ and SF₆ are less soluble in water than is helium. This could lead (a) to practical advantages if these gases were used as components of a breathing mixture for divers, and (b) to a route to the understanding of the mechanisms of inert gas narcosis (general anaesthesia) and decompression sickness. Professor W.D.M. Paton of the Department of Pharmacology was also interested in these problems, and a joint investigation was promoted.

With Keith Miller, the first graduate student in this area, and now the Mallinckrodt Professor of Anaesthetics at Harvard, and John Lever, now Lecturer at Imperial College, London, it was discovered that the symptoms experienced at very great depths by divers breathing a mixture of air and helium are due, not to the helium, but to the effects of pressure per se. (There effects are now called the High Pressure Neurological Syndrome - HPNS). This conclusion was confirmed by experiments on newts, and it was later discovered that the effects of general anaesthesia in mammals can be reversed by pressure - an effect observed in tadpoles some years earlier - and, conversely, that the addition of an anaesthetic gas - such as nitrogen at high pressure - can protect against the effect of pressure (as is now used in Tri-mix diving). The work of the group also involved the study of decompression sickness. First divided between the Department of Pharmacology and the PCL, the hyperbaric group was relocated in the PCL in 1983.

Steve Daniels joined the group in 1973 as a Part II student with his own idea for the ultrasonic imaging of very small bubbles. This original and successful invention is now being used to monitor divers on many research dives all over Europe.

The work of the group is now directed towards elucidation of the relationship between gas bubbles and patho-physiological changes and the identification of the specific neurotransmitter systems that are sensitive to pressure. In particular, the glycine receptor is believed to play an important role in determining the effects of pressure on the central nervous system.

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