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Special Issue Persistent Foramen Ovale and Decompression Illness This copy of Diving and Hyperbaric Medicine is for personal use only. Distribution is prohibited by Copyright Law. The Journal of the South Pacifi c Underwater Medicine Society and the European Underwater and Baromedical Society Volume 45 No. 2 June 2015 Special issue Persistent foramen ovale and decompression illness First-aid O2 devices for injured divers: which and how much O2? Are skin bends due to brain injury in decompression illness? Does alcohol protect rats from decompression sickness? Survival from ‘poppers’ and alcohol: a role for HBOT? Print Post Approved PP 100007612 ISSN 1833-3516, ABN 29 299 823 713 This copy of Diving and Hyperbaric Medicine is for personal use only. Distribution is prohibited by Copyright Law. Diving and Hyperbaric Medicine Volume 45 No. 2 June 2015 PURPOSES OF THE SOCIETIES To promote and facilitate the study of all aspects of underwater and hyperbaric medicine To provide information on underwater and hyperbaric medicine To publish a journal and to convene members of each Society annually at a scientifi c conference SOUTH PACIFIC UNDERWATER EUROPEAN UNDERWATER AND MEDICINE SOCIETY BAROMEDICAL SOCIETY OFFICE HOLDERS OFFICE HOLDERS President President David Smart <[email protected]> Costantino Balestra <[email protected]> Past President Vice President Michael Bennett <[email protected]> Jacek Kot <[email protected]> Secretary Immediate Past President Doug Falconer <[email protected]> Peter Germonpré <[email protected]> Treasurer Past President Peter Smith <[email protected]> Alf Brubakk <[email protected]> Education Offi cer Honorary Secretary David Wilkinson <[email protected]> Peter Germonpré <[email protected]> Chairman ANZHMG Member-at-Large 2014 John Orton <[email protected]> Robert van Hulst <[email protected]> Committee Members Member-at-Large 2013 Denise Blake <[email protected]> Pierre Lafère <[email protected]> Simon Mitchell <[email protected]> Member-at-Large 2012 Janine Gregson <[email protected]> Lesley Blogg <[email protected]> Webmaster Liaison Offi cer Joel Hissink <[email protected]> Phil Bryson <[email protected]> ADMINISTRATION ADMINISTRATION Membership Honorary Treasurer and Membership Secretary Steve Goble <[email protected]> Patricia Wooding <[email protected]> 16 Burselm Avenue, Hainault, Ilford MEMBERSHIP Essex, IG6 3EH, United Kingdom For further information on SPUMS and to complete a membership Phone & Fax: +44-(0)20-85001778 application, go to the Society’s website: <www.spums.org.au> The offi cial address for SPUMS is: MEMBERSHIP c/o Australian and New Zealand College of Anaesthetists, For further information on EUBS and to complete a membership 630 St Kilda Road, Melbourne, Victoria 3004, Australia application, go to the Society’s website: <www.eubs.org> SPUMS is incoprorated in Victoria A0020660B DIVING AND HYPERBARIC MEDICINE <www.dhmjournal.com> Editor: Editorial Board: Michael Davis <[email protected]> Michael Bennett, Australia P O Box 35 Alf Brubakk, Norway Tai Tapu 7645 David Doolette, USA New Zealand Peter Germonpré, Belgium Phone: +64-(0)3-329-6857 Jane Heyworth, Australia Jacek Kot, Poland European (Deputy) Editor: Simon Mitchell, New Zealand Lesley Blogg <[email protected]> Claus-Martin Muth, Germany Editorial Assistant: Neal Pollock, USA Nicky McNeish <[email protected]> Monica Rocco, Italy Journal distribution: Martin Sayer, United Kingdom Steve Goble <[email protected]> Erika Schagatay, Sweden David Smart, Australia Journal submissions: Robert van Hulst, The Netherlands Submissions should be made at http://www.manuscriptmanager.com/dhm Diving and Hyperbaric Medicine is published jointly by the South Pacifi c Underwater Medicine Society and the European Underwater and Baromedical Society (ISSN 1833-3516, ABN 29 299 823 713) This copy of Diving and Hyperbaric Medicine is for personal use only. Distribution is prohibited by Copyright Law. Diving and Hyperbaric Medicine Volume 45 No.2 June 2015 73 Editorial Persistent (patent) foramen ovale (PFO): nor universally accepted. First of all, the exact prevalence implications for safe diving of PFO in divers is not known. As it has been pointed out in the recent literature, a contrast echocardiography (be it Diving medicine is a peculiar specialty. There are physicians transthoracic or trans-oesophageal) or Doppler examination and scientists from a wide variety of disciplines with an is only reliable if performed according to a strict protocol, interest in diving and who all practice ‘diving medicine’: taking into account the very many pitfalls yielding false the study of the complex whole-body physiological negative results.10 The optimal procedure for injection of changes and interactions upon immersion and emersion. To contrast medium was described several years ago, but has not understand these, the science of physics and molecular gas received enough attention.11,12 Indeed, it is our and others’ and fl uid movements comes into play. The ultimate goal of experience that many divers presenting with PFO-related practicing diving medicine is to preserve the diver’s health, DCI symptoms initially are declared “PFO-negative” by both during and after the dive. Good medicine starts with eminent, experienced cardiologists! prevention. For most divers, underwater excursions are not a professional necessity but a hobby; avoidance of risk is Failing a prospective study, the risks of diving with a right-to- generally a much better option than risk mitigation or cure. left vascular shunt can only be expressed as an ‘odds ratio’, However, prevention of diving illnesses seems to be even which is a less accurate measure than is ‘relative risk’. The more diffi cult than treating those illnesses. DAN Europe Carotid Doppler Study,13 started in 2001, is nearing completion and will provide more insight into the The papers contained in this issue of DHM are a nice mix actual risks of DCI for recreational divers. of various aspects of PFO that divers are interested in, all of them written by specialist doctors who are avid divers The degree of DCI risk reduction from closing a PFO is themselves. However, diving medicine should also take thus not only dependent on successful closure but also advantage of research from the “non-diving” medicine (mostly?) on how the diver manages his/her dive and community, and PFO is a prime example. Cardiology and decompression in order to reduce the incidence of VGE. It neurology have studied PFO for as long, or even longer than has been convincingly shown that conservative dive profi les divers have been the subjects of PFO research, and with reduce DCI incidence even in divers with large PFOs,14,15 much greater numbers and resources. Unexplained stroke just as PFO closure does not protect completely from DCI has been associated with PFO, as has severe migraine with if the dive profi les are aggressive.7,16 Prospective studies aura. As the association seems to be strong, investigating should not only focus on the reduction of DCI incidence the effect of PFO closure was a logical step. Devices have after closure, but should take into account the costs and side been developed and perfected, allowing now for a relatively effects of the procedure, as has been done in the cardiology low-risk procedure to ‘solve the PFO problem’. However, and neurology studies. as with many things in science, the results have not been spectacular as hoped for: patients still get recurrences of Imagine lung transplants becoming a routine operation, stroke, still have migraine attacks. The risk-benefi t ratio of costly but with a high success rate; imagine also a long- PFO closure for these non-diving diseases is still debated.1,2 term smoker suffering from a mild form of obstructive For personallung disease use and exercise-limiting only dyspnoea. Which of two For diving, we now face a similar problem. Let there be options would you recommend: having a lung transplant and no doubt that PFO is a pathway through which venous gas continue smoking as before, or quit smoking and observe emboli (VGE) can arterialize, given suffi ciently favourable a progressive improvement of pulmonary and cardiac circumstances (such as: a large quantity of VGE, size of pathology? As opposed to patients with thrombotic disease the PFO, straining or provocation manoeuvres inducing and migraine, divers can choose to reduce DCI risk. In fact, increased right atrial pressure, delayed tissue desaturation all it takes is acceptance that some types of diving carry too so that seeding arterial gas emboli (AGE) grow instead of high a health risk – whether it is because of a PFO or another shrink, and there may be other, as yet unknown factors). 3–6 ‘natural’ factor.17 It would be unethical to promote PFO There is no doubt that closing a PFO, either surgically or closure in divers solely on the basis of its effi cacy of shunt using a catheter-delivered device, can reduce the number reduction. Unfortunately, at least one device manufacturer of VGE becoming AGE.7 There is also no doubt that the has already done so in the past, citing various publications procedure itself carries some health risks which are, at 1% or to specifi cally target recreational divers. Some technical higher risk of serious complications, an order of magnitude diving organizations even have recommended preventive greater than the risk for decompression illness (DCI) in PFO closure in order to undertaking high-risk dive training. recreational diving.8,9 As scientists, we must not allow ourselves to be drawn into Scientists seek the ‘truth’, but the truth about how much of a intuitive diver fears and beliefs. Nor should we let ourselves risk PFO represents for divers is not likely to be discovered be blinded by the ease and seemingly low risk of the This copy of Diving and Hyperbaric Medicine is for personal use only. Distribution is prohibited by Copyright Law.
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