Fitness to dive
Most cases of recreational drug use result in an impaired fitness to dive, and a significantly increased risk of sub-optimal response to emergencies.
General physical fitness requirements are also often specified by a certifying agency, and are usually related to ability to swim and perform the activities that are associated with the relevant type of diving.
Some agencies place the responsibility for assessing fitness largely on the individual diver, while others require an examination by a registered medical practitioner based on specified criteria.
These criteria are generally consistent across certification agencies and are adapted from standards for professional divers, though they may be somewhat relaxed for recreational diving.
Occasionally divers have provided deliberately falsified medical forms, stating that they do not have conditions which would disqualify them from diving, sometimes with fatal consequences.
Some drugs which affect brain function have unpredictable effects on a diver exposed to high pressure in deep diving.
[15] Some medical conditions may temporarily or permanently disqualify a person from diving depending on severity and the specific requirements of the registration body.
In the past, asthma was generally considered a contraindication for diving due to theoretical concern about an increased risk for pulmonary barotrauma and decompression sickness.
[16] Cancers are generally considered a class of abnormal, fast growing and disordered cells which have the potential to spread to other parts of the body.
[18][19] Current (2016) medical opinion of Divers Alert Network (DAN) and the Diving Diseases Research Centre (DDRC) is that diabetics should not dive if they have any of the following complications: DAN makes the following recommendations for additional precautions by diabetic divers: Epilepsy is a central nervous system disorder in which the person has had at least two seizures, often for no discernible cause.
As a seizure may involve loss of consciousness, this puts the convulsing diver at significant risk, particularly on scuba with half mask and demand valve, which may become dislodged.
[21] Very little reliable epidemiological evidence exists to suggest that a past history of seizures may correlate with increased risk to recreational scuba divers.
[21] Most objections to allowing people who have a long history of no seizures to dive are largely theoretical, and in many cases entirely unsupported by reliable evidence.
These courses teach divers and instructors how to adapt techniques and equipment to different disabilities, ensuring safe and enjoyable dives.
A patent foramen ovale (PFO), or atrial shunt can potentially cause a paradoxical gas embolism by allowing venous blood containing what would normally be asymptomatic inert gas decompression bubbles to shunt from the right atrium to the left atrium during exertion, and can be then circulated to the vital organs where an embolism may form and grow due to local tissue supersaturation during decompression.
This congenital condition is found in roughly 25% of adults, and is not listed as a disqualifier from diving nor as a required medical test for professional or recreational divers.
[31][34] A grading system based on severity of illness is suggested as a guideline (July 2021), with the understanding that individual circumstances may differ, and that this model is subject to revision as and when further data becomes available.
Psychological profiles indicating intelligence and below average neuroticism tend to correlate with successful diving activity over the long term.
Divers who are prone to trait anxiety are more likely to mismanage a developing emergency by panicking and missing the opportunity to recover from the initial incident.
[44] Training can help a diver to recognize rising stress levels, and allow them to take corrective action before the situation deteriorates into an injury or fatality.
[46] In 1998 the Recreational Scuba Training Council listed "a history of panic disorder" as an absolute contraindication to scuba diving, but the 2001 guideline specifies "a history of untreated panic disorder" as a severe risk condition, which suggests that some people who are being treated for the condition might dive at an acceptable level of risk.
[49][50] Recreational scuba diving may be considered an extreme sport since personal risk is involved,[51] but it is also a leisure activity conducted for entertainment and relaxation.
The need to focus on the activities and skills and the tendency to become enthralled by the underwater environment enables divers to leave their worries above the surface.
The risks are managed by the use of specialized equipment, avoidance of single points of failure by teamwork and equipment redundancy, the use of procedures known to be effective, maintenance of a high level of skill, sufficient physical fitness to perform effectively in the expected conditions and any reasonably foreseeable contingency, and appropriate reaction to contingencies.
The way in which a diver reacts to the environment is influenced by attitude, awareness, physical fitness, self-discipline, and the ability to distinguish reality from perception.
[54] In a situation where there is no simple and direct escape to safety, reaction to stress can determine the difference between an enjoyable dive and an accident that may lead to death or disability.
When this kind of stress causes the diver to increase gas consumption due to overreacting, the problem gets worse and can spiral into an unrecoverable incident.
Any advice given by a medical practitioner is based on educated (to a greater or lesser extent), but unproven assumption, and each case is best evaluated by an expert.
When considering allowing or barring someone with psychological problems to dive, the certifying physician must be aware of all the possibilities and variations in the specific case.
Some of the medication types which are commonly or occasionally known to be used by active divers are listed here, along with possible side effects and complications:[57] Over the counter drugs are generally considered safe for consumer use when the directions for use are followed.
