condition exists. the other important medicals are after some significant illness, where medical intervention is needed there and has to be done by a doctor who is competent in diving medicine, and can not be done by prescriptive rules. psychological factors can affect fitness to dive, particularly where they affect response to emergencies, or risk taking behaviour. the use of medical and recreational drugs, can also influence fitness to dive, both for physiological and behavioural reasons. in some cases prescription drug use may have a net positive effect, when effectively treating an underlying condition, but frequently the side effects of effective medication may have undesirable influences on the fitness of diver, and most cases of recreational drug use result in an impaired fitness to dive, and a significantly increased risk of sub-optimal response to emergencies. education and registration of practitioners specialist training in underwater and hyperbaric medicine is available from several institutions, and registration is possible both with professional associations and governmental registries. education noaa/uhms physicians training course in diving medicine this course has been presented since 1977, and has been influenced by internationally accepted training objectives recommended by the diving medical advisory committee, the european diving technology committee, and the european committee for hyperbaric medicine. the course is designed for qualified medical practitioners, but may be useful to others who work in the field of diving safety and operations. the course is to train physicians to recognize and treat diving medical emergencies. subject matter includes: basic physics and physiology of the hyperbaric environment: the laws and principles; the differences between hyperbaric and hypobaric pressure; hyperbaric gases and their effects under pressure; links between the physiological effects of the hyperbaric environment and the pathology of the disease basic decompression theory: historical development to current concepts factors affecting decompression safety including acceptable risks and thermal issues distinguish decompression sickness from barotrauma and arterial gas embolism; dive computer theories and types, and comparison to dive tables introduction to commercial diving and comparison to recreational and technical diving, including differences in procedures, equipment, and diver categories the clinical application of hyperbaric oxygen therapy and the treatment tables used; participation in surface-supplied diving operation and hyperbaric chamber operations; components, types, operational and safety hazards associated with hyperbaric chambers; diving-related conditions resulting from the effects of long-term effects of diving, flying after diving, altitude, thermal conditions, age and gender neurologic assessment on a diver with signs and/or symptoms of dci medical and fitness standards for diving, including: contraindications for both commercial and recreational divers differences in medical standards for recreational versus occupational diving communities legal implications for approving and denying fitness to dive in an occupational setting approaches for determining the safety of prescription and otc medications used by divers fellowship in undersea and hyperbaric medicine the accreditation council for graduate medical education (acgme) and the american osteopathic association (aoa) offer 12-month programs in undersea and hyperbaric medicine associated with acgme or aoa accredited programs in emergency medicine, family medicine, internal medicine, occupational medicine, preventive medicine, or anesthesiology. echm-edtc educational and training standards for physicians in diving and hyperbaric medicine the standard drawn up jointly by the european committee for hyperbaric medicine and the european diving technical committee defines job descriptions for several levels of diving and hyperbaric physician: education and assessment to these standards may be provided by institutions of higher education under the leadership of a level 3 hyperbaric medicine expert as defined below. certificates of competence may be issued by a nationally accredited institution or an internationally acknowledged agency, and periodic recertification is required. level 1. medical examiner of divers (med) minimum 28 teaching hours. the med must be competent to perform the assessments of medical fitness to dive of occupational and recreational divers and compressed air workers, except the assessment of medical fitness to resume diving after major decompression incidents. level 2d. diving medicine physician (dmp) minimum 80 teaching hours. a dmp must be competent to perform the initial and all other assessments of medical fitness to dive of working and recreational divers or compressed air workers, and manage diving accidents and advise diving contractors and others on diving medicine and physiology (with the backup of a diving medical expert or consultant). a dmp should have knowledge in relevant aspects of occupational health, but is not required to be a certified specialist in occupational medicine. a dmp should have certified skills and basic practical experience in assessment of medical fitness to dive, management of diving accidents, safety planning for professional diving operations, advanced life support, acute trauma care and general wound care. level 2h. hyperbaric medicine physician (hmp) minimum 120 teaching hours an hmp will be responsible for hyperbaric treatment sessions (with the backup of a hyperbaric medicine expert or consultant) an hmp should have appropriate experience in anaesthesia and intensive care in order to manage the hbo patients, but is not required to be a certified specialist in anaesthesia and intensive care. an hmp must be competent to assess and manage clinical patients for hyperbaric oxygen therapy treatment level 3. hyperbaric medicine expert or consultant (hyperbaric and diving medicine) is a physician who has been assessed as competent to: manage a hyperbaric facility (hbo centre) or the medical and physiological aspects of complex diving activities. manage research programs on diving medicine. supervise a team of hbo doctors and personnel, health professionals and others. teach relevant aspects of hyperbaric medicine and physiology to all members of staff. gesellschaft für tauch- und überdruckmedizin e. v. society for diving and hyperbaric medicine german standards for education and assessment of diving medical practitioners are similar to the echm-edtc standards and are controlled by the gesellschaft für tauch- und überdruckmedizin e. v. they include medical examiner of divers, diving medicine physician, hyperbaric medicine physician, chief hyperbaric medicine physician and hyperbaric medicine consultant. schweizerische gesellschaft für unterwasser- und hyperbarmedizin swiss society for underwater and hyperbaric medicine. swiss standards for education and assessment of diving medical practitioners are controlled by the schweizerische gesellschaft für unterwasser- und hyperbarmedizin. they include medical examiner of divers, diving medicine physician and hyperbaric medicine physician. österreichische gesellschaft für tauch- und hyperbarmedizin austrian society for diving and hyperbaric medicine. austrian standards for education and assessment of diving medical practitioners are controlled by the österreichische gesellschaft für tauch- und hyperbarmedizin they include medical examiner of divers, diving medicine physician, hyperbaric medicine physician, chief hyperbaric medicine physician and hyperbaric medicine consultant. registration the american medical association recognises the sub-speciality undersea and hyperbaric medicine held by someone who is already board certified in some other speciality. the south african department of employment and labour registers two levels of diving medical practitioner. level 1 is qualified to conduct annual examinations and certification of medical fitness to dive, on commercial divers (equivalent to echm-edtc level 1. medical examiner of divers), and level 2 is qualified to provide medical advice to a diving contractor and hyperbaric treatment for diving injuries (equivalent to echm-edtc level 2d diving medicine physician) australia has a four tier system: in 2007 there was no recognised equivalence with the european standard. gps completing the first tier four- to five-day course on how to examine divers for ‘fitness to dive’ can then add their names to the spums diving doctors list gps completing the second tier two-week diving medicine courses provided by the royal australian navy and the royal adelaide hospital, or the two-week course in diving and hyperbaric medicine provided by the anz hyperbaric medicine group, qualify to do commercial-diving medicals. the third tier is the spums diploma in diving and hyperbaric medicine. the candidate must attend a two-week course, write a dissertation related to dhm and have the equivalent of six months’ full-time experience working in a hyperbaric medicine unit. the fourth tier is the certificate in diving and hyperbaric medicine from the anz college of anaesthetists. training of divers and support staff in relevant first aid divers a basic knowledge understanding of the causes, symptoms and first aid treatment of diving related disorders is part of the basic training for most recreational and professional divers, both to help the diver avoid the disorders, and to allow appropriate action in case of an incident resulting in injury. recreational divers a recreational diver has the same duty of care to other divers as any ordinary member of the public, and therefore there is no obligation to train recreational divers in first aid or other medical skills. nevertheless, first aid training is recommended by most, if not all, recreational diver training agencies. recreational diving instructors and divemasters, on the other hand, are to a greater or lesser extent responsible for the safety of divers under their guidance, and therefore are generally required to be trained and certified to some level of rescue and first aid competence, as defined in the relevant training standards of the certifying body. in many cases this includes certification in cardiopulmonary resuscitation and first aid oxygen administration for diving accidents. professional divers professional divers usually operate as members of a team with a duty of care for other members of the team. divers are expected to act as standby divers for other members of the team and the duties of a standby diver include rescue attempts if the working diver gets into difficulties. 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. 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. the level of first aid training, competence and certification will generally take this into account. in south africa, registered commercial and scientific divers must hold current certification in first aid at the national level 1, with additional training in oxygen administration for diving accidents, and registered diving supervisors must hold level 2 first aid certification. offshore diving contractors frequently follow the imca recommendations. diver medic a diver medic or diving medical technician is a member of a dive team who is trained in advanced first aid. 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. the diver medic must hold, at a minimum, a valid certificate of medical fitness to operate in a pressurized environment, and a certificate of medical fitness to dive. training standards for diver medic are described in the imca scheme for recognition of diver medic training. ethical and medicolegal issues experimental work on human subjects is often ethically and/or legally impracticable. tests where the endpoint is symptomatic decompression sickness are difficult to authorise and this makes the accumulation of adequate and statistically valid data difficult. the precautionary principle may be applied in the absence of information allowing a realistic assessment of risk. analysis of investigations into accidents is useful when reliable results are available, which is less often than would be desirable, but privacy concerns prevent a large mount of information potentially useful to the general diving population from being made available to researchers. history of diving medical research timeline november 1992: the first examination for certification in undersea medicine by the american board of preventive medicine. november 1999: the first examination for undersea and hyperbaric medicine qualification. notable researchers arthur j. bachrach albert r. behnke peter b. bennett thomas e. berghage paul bert george f. bond alf o. brubakk albert a. bühlmann carl edmonds william paul fife john scott haldane robert william hamilton jr. leonard erskine hill brian andrew hills f.j. keays christian j. lambertsen joseph b. macinnis simon mitchell richard e. moon františek novomeský john rawlins charles wesley shilling edward d. thalmann richard d. vann james vorosmarti r.m. wong robert d. workman research organisations defence and civil institute of environmental medicine dciem is a combined military and civilian research organisation to research the