Diving medicine
The field includes the effect of breathing gases and their contaminants under high pressure on the human body and the relationship between the state of physical and psychological health of the diver and safety.
[citation needed] The scope of knowledge necessary for a practitioner of diving medicine includes the medical conditions associated with diving and their treatment, physics and physiology relating to the underwater and pressurised environment, the standard operating procedures and equipment used by divers which can influence the development and management of these conditions, and the specialised equipment used for treatment.
Nitrox, which contains more oxygen and less nitrogen is commonly used as a breathing gas to reduce the risk of decompression sickness at recreational depths (up to about 40 metres (130 ft)).
The results may range from pain in the joints where the bubbles form to blockage of an artery leading to damage to the nervous system, paralysis or death.
[5] Gas bubbles within the arterial circulation can block the supply of blood to any part of the body, including the brain, and can therefore manifest a vast variety of symptoms.
Nitrogen narcosis is caused by the pressure of dissolved gas in the body and produces temporary impairment to the nervous system.
[12] Normobaric oxygen administration at the highest available concentration is frequently used as first aid for any diving injury that may involve inert gas bubble formation in the tissues.
In the 21st century, it is a highly specialized treatment modality found to be effective for treating many conditions where the administration of oxygen under pressure is beneficial.
The most important medical examination is the one before starting diving, as the diver can be screened to prevent exposure when a dangerous condition exists and a baseline established.
Specialist training in underwater and hyperbaric medicine is available from several institutions, and registration is possible both with professional associations and governmental registries.
Certificates of competence may be issued by a nationally accredited institution or an internationally acknowledged agency, and periodic recertification is required.
Swiss standards for education and assessment of diving medical practitioners are controlled by the Schweizerische Gesellschaft für Unterwasser- und Hyperbarmedizin.
[32] The American Medical Association recognises the sub-speciality Undersea and Hyperbaric Medicine held by someone who is already Board Certified in some other speciality.
Consequently, professional divers are generally required to be trained in rescue procedures appropriate to the modes of diving they are certified in, and to administer first aid in emergencies.
The specific training, competence and registration for these skills varies, and may be specified by state or national legislation or by industry codes of practice.
[34][39] Diving supervisors have a similar duty of care, and as they are responsible for operational planning and safety, generally are also expected to manage emergency procedures, including the first aid that may be required.
[40] A diver medic recognised by IMCA must be capable of administering first aid and emergency treatment, and carrying out the directions of a physician, and be familiar with diving procedures and compression chamber operation.
The diver medic must also be able to assist the diving supervisor with decompression procedures, and provide treatment in a hyperbaric chamber in an emergency.
Dysbaric osteonecrosis has long been associated with hyperbaric exposure requiring staged decompression, and has become a notifiable industrial disease.
[42][43] Subclinical effects can occur without immediately noticeable presentations of decompression sickness, as is shown by dysbaric osteronecrosis and hearing deficiencies developing over the longer term in professional divers.
Recreational divers may also be at risk for long term development of symptoms affecting the lungs, eyes, ears, and central nervous system.
[44] Besides osteonecrosis and hearing losses, there is no substantial consensus about what the long term risks actually are, but the medical literature and anecdotal evidence both suggest that there are potential chronic long-term detrimental effects of diving.
[42] Thorsen et al 1990 compared observations of saturation divers with matched controls, and found changes consistent with small airways dysfunction which suggested cumulative long term effects of diving exposure on lung function.
Myopic shifts are usually reversible and resolve within days to months, but cataracts are permanent and if sufficiently advanced will require lens replacement surgery.
There seems to be a threshold of inert gas load or decompression stress needed to induce the condition, but the actual values remain obscure.
Divers appear to be at greater risk for long term cochlear-vestibular damage and associated high frequency hearing loss.
They reached the conclusion that male former divers are more likely to experience these symptoms than the general population, but did not claim this to be specifically caused by diving, as it could have been a consequence of the associated strenuous physical activity.
[48] A 1991 study on saturation divers indicated significantly higher deficits in the central nervous system th the control group in the time span of one to seven years since their last deep dive.
[51] The Diving Diseases Research Centre (DDRC) is a British hyperbaric medical organisation located near Derriford Hospital in Plymouth, Devon.
