Citation

Schipke JD, Muth T, Cleveland S. Diving Hyperb. Med. 2012; 42(2): 105-106.

Affiliation

Research Group Experimental Surgery, University Hospital Düsseldorf, Germany, Forschungsgruppe Experimentelle Chirurgie, Klinik für Thorax- und Kardiovaskuläre Chirurgie, Universitätsklinikum Düsseldorf, Moorenstr. 5, D-40225 Düsseldorf, Germany, Phone: +49-(0)211-811-4721, Fax: +49-(0)211-811-5334, E-mail: j.schipke@gmx.org.

Copyright

(Copyright © 2012, South Pacific Underwater Medicine Society and European Underwater and Baromedical Society)

DOI

unavailable

PMID

22828822

Abstract

Dear Editor, We agree with Dr Walker's concerns about risks associated with breath-hold diving, voiced after Professor Schagatay's first review in 2009 in this journal.1,2 We thank Professor Schagatay for her very thorough reviews, but only agree in part with her view that reporting increases safety, as breath-hold deep diving per se is unsafe.2,3,4 To weave a scientific lifebelt for this high-risk activity is inappropriate. We also doubt that uncritical reporting increases safety. We also believe that it is scientifically unsound to recommend so-called 'proper techniques for preparation and performance' to achieve 'maximal performance'. We list below some of the serious pitfalls that could evolve from reading parts of the most recent review.4 Competitors in static/dynamic apnea experience extended hypoxia. While acutely elevated levels of a marker of brain damage may not be of major relevance, long-term, possibly cumulative effects must be suspected.5 If extended breath-holding alone poses serious risks for unconsciousness, brain injury and death,6 then breath-hold deep diving adds risks associated with the effect of increased ambient pressure on gas volumes and increased partial pressures. If a coach advises the use of new hydrodynamic goggles, almost frictionless dolphin-skinned swim suits and more efficient power fins, then he does not harm the athlete. If the ambitious breath-hold deep diving athlete reads about 'tricks' on how to fool physics, then he is seriously endangered. After reading Training, preparation and equalization to avoid barotrauma (p. 220ff.) he feels encouraged to perfect his glossopharyngeal insufflation (GI) and exsufflation (GE) to prevent descent barotrauma,4 but he would thus go from bad to worse, as such techniques can do harm. Describing techniques without describing possible deleterious consequences seems too short-sighted. GI might considerably increase intrathoracic pressures (up to 80 cmH2O) with an increased risk of pulmonary barotraumas and arterial gas embolism.7 In turn, increased intrathoracic pressures will likely impede venous return, inducing hypotension with consequences varying from dizziness to fainting just prior to diving. Submersion shifts blood towards the chest, and more blood is shifted as ambient pressure increases. Thus, all thoracic structures with a high compliance are considerably enlarged. In consequence, chest sonography frequently documents pulmonary oedema after immersion,8 and great depths are associated with the risk of pulmonary barotrauma (lung squeeze). GE can seemingly increase the risk of lung squeeze by taking some mouth-fills of air from the lungs and should not be presented by a coach without its serious hazards being explained. While haemoptysis is the visible consequence of acute pulmonary barotrauma, any less severe damage might remain subclinical. Hence, regular competitive apnea diving over a few seasons might carry a chronic cardiopulmonary risk leading from early functional changes to the manifestation of pulmonary hypertension.9 Regarding lung squeeze, it should be noted that involuntary contractions of the thorax and diaphragm can produce waves of negative pressure.10 Once intrathoracic pressure is already negative at great depth, additional negative pressure waves might well damage the pulmonary capillaries. Finally, the risk of decompression sickness (DCS) after breath-hold dives has been considered by Dr Schagatay. After a breath-hold diver has suffered from cerebral DCS, such athletes should only perform extensive breath-hold activities near a treatment chamber.

Keywords: Drowning; Drowning Prevention; Water Safety

Language: en