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Titolo:
Recreational scuba diving, patent foramen ovale and their associated risks
Autore:
Schwerzmann, M; Seiler, C;
Indirizzi:
Univ Hosp Bern, Inselspital, Swiss Cardiovasc Ctr Bern, CH-3010 Bern, Switzerland Univ Hosp Bern Bern Switzerland CH-3010 Bern, CH-3010 Bern, Switzerland
Titolo Testata:
SWISS MEDICAL WEEKLY
fascicolo: 25-26, volume: 131, anno: 2001,
pagine: 365 - 374
SICI:
1424-7860(20010630)131:25-26<365:RSDPFO>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
CENTRAL-NERVOUS-SYSTEM; DECOMPRESSION-SICKNESS; COMPLEMENT ACTIVATION; PARADOXICAL EMBOLISM; PREVENT RECURRENCE; OXYGEN RADICALS; PULMONARY-EDEMA; AIR-EMBOLISM; SPORT DIVERS; DAMAGE;
Keywords:
diving; pathophysiology; decompression illness; patent foramen ovale;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Citazioni:
80
Recensione:
Indirizzi per estratti:
Indirizzo: Schwerzmann, M Univ Klin Bern, Inselspital, Gefasszentrum Bern, CH-3010 Bern, Switzerland Univ Klin Bern Bern Switzerland CH-3010 Bern, Switzerland
Citazione:
M. Schwerzmann e C. Seiler, "Recreational scuba diving, patent foramen ovale and their associated risks", SWISS MED W, 131(25-26), 2001, pp. 365-374

Abstract

Scuba diving has become a popular leisure time activity with distinct risks to health owing to its physical characteristics. Knowledge of the behaviour of any mixture of breathable gases under increased ambient pressure is crucial for safe diving and gives clues as to the pathopyhsiology of compression or decompression related disorders. Immersion in cold water augments cardiac pre- and afterload due to an increase of intrathoracic blood volume and peripheral vasoconstriction. In veryrare cases, the vasoconstrictor response can lead to pulmonary oedema. Immersion of the face in cold water is associated with bradycardia mediated byincreased vagal tone. In icy water, the bradycardia can be so pronounced, that syncope results. For recreational dives, compressed air (ie, 4 parts nitrogen and 1 part oxygen) is the preferred breathing gas. Its use is limited for diving to 40 to 50 m, otherwise nitrogen narcosis ("rapture of the deep") reduces a diver's cognitive function and increases the risk of inadequate reactions. At depths of 60 to 70 m oxygen toxicity impairs respiration and at higher partial pressures also functioning of the central nervous system. The use of special nitrogen-oxygen mixtures ("nitrox", 60% nitrogen and 40% oxygen as the typical example) decreases the probability of nitrogen narcosis and probably bubble formation, at the cost of increased risk of oxygen toxicity. Most of the health hazards during dives are consequences of changes in gasvolume and formation of gas bubbles due to reduction of ambient pressure during a diver's ascent. The term barotrauma encompasses disorders related to over expansion of gas filled body cavities (mainly the lung and the innerear). Decompression sickness results from the growth of gas nuclei in predominantly fatty tissue. Arterial gas embolism describes the penetration of such gas bubbles into the systemic circulation, either due to pulmonary barotrauma, transpulmonary passage after massive bubble formation ("chokes") or cardiac shunting. In recreational divers, neurological decompression events comprise 80% of reported cases of major decompression problems, most of the time due to pathological effects of intravascular bubbles. In divers with a history of major neurological decompression symptoms without evident cause, transoesophageal echocardiography must be performed to exclude a patent foramen ovale. If a cardiac right-to-left shunt is present, we advise divers with a historyof severe decompression illness to stop diving. If they refuse to do so, it is crucial that they change their diving habits, minimising the amount ofnitrogen load on the tissue. There is ongoing debate about the long term risk of scuba diving. Neuro-imaging studies revealed an increased frequency of ischaemic brain lesions indivers, which do not correlate well with subtle functional neurological deficits in experienced divers. In the light of the high prevalence of venousgas bubbles even after dives in shallow water and the presence of a cardiac right-to-left shunt in a quarter of the population (ie, patent foramen ovale), arterialisation of gas bubbles might be more frequent than usually presumed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/01/20 alle ore 12:18:23