Diving disorders

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Diving disorders, or diving related medical conditions, are conditions associated with underwater diving, and include both conditions unique to underwater diving, and those that also occur during other activities. This second group further divides conditions caused by exposure to ambient pressures significantly different from surface atmospheric pressure, and a range of conditions caused by general environment and equipment associated with diving activities.

Contents

Disorders particularly associated with diving include those caused by variations in ambient pressure, such as barotraumas of descent and ascent, decompression sickness and those caused by exposure to elevated ambient pressure, such as some types of gas toxicity. There are also non-dysbaric disorders associated with diving, which include the effects of the aquatic environment, such as drowning, which also are common to other water users, and disorders caused by the equipment or associated factors, such as carbon dioxide and carbon monoxide poisoning. General environmental conditions can lead to another group of disorders, which include hypothermia and motion sickness, injuries by marine and aquatic organisms, contaminated waters, man-made hazards, and ergonomic problems with equipment. Finally there are pre-existing medical and psychological conditions which increase the risk of being affected by a diving disorder, which may be aggravated by adverse side effects of medications and other drug use.

Treatment depends on the specific disorder, but often includes oxygen therapy, which is standard first aid for most diving accidents, and is hardly ever contra-indicated for a person medically fit to dive, and hyperbaric therapy is the definitive treatment for decompression sickness. Screening for medical fitness to dive can reduce some of the risk for some of the disorders.

Effects of variation in ambient pressure

Mask squeeze barotrauma of descent Mask Squeeze.jpg
Mask squeeze barotrauma of descent

Many diving accidents or illnesses are related to the effect of pressure on gases in the body.

Barotrauma

Main article: Barotrauma

Barotrauma is physical injury to body tissues caused by a difference in pressure between a gas space inside or in contact with the body, and the surroundings. [1] [2]

Barotrauma occurs when the difference in pressure between the surroundings and the gas space makes the gas expand in volume, distorting adjacent tissues enough to rupture cells or damage tissue by deformation. A special case, where pressure in tissue is reduced to the level that causes dissolved gas to come out of solution as bubbles, is called decompression sickness , the bends, or caisson disease.

Several organs are susceptible to barotrauma; however, the cause is well understood and procedures for avoidance are clear. Nevertheless, barotrauma occurs and can be life-threatening, and procedures for first aid and further treatment are an important part of diving medicine.

Barodontalgia Barodontalgia.svg
Barodontalgia

Compression arthralgia

Main article: Compression arthralgia
Compression arthralgia is pain in the joints caused by exposure to high ambient pressure at a relatively high rate of compression, experienced by underwater divers. Also referred to in the US Navy Diving Manual as compression pains. Fast compression (descent) may produce symptoms as shallow as 30 msw. At depths beyond 180m even very slow compression may produce symptoms. The pain may be sufficiently severe to limit the diver's capacity for work, and may also limit travel rate and depth of downward excursions by saturation divers. The symptoms generally resolve during decompression and require no further treatment. [3]

Decompression sickness

Main article: Decompression sickness
Decompression sickness is a condition caused by dissolved gases coming out of solution as bubbles in the tissues and fluids of the body during and directly after depressurisation. DCS is best known as a hazard of underwater diving but may occur in other decompression events such as caisson work, flying in unpressurised aircraft, and extra-vehicular activity from spacecraft. Since bubbles can form in any part of the body, or migrate via the bloodstream to any part of the body, DCS can produce a wide range of symptoms, and its effects may vary from joint pain and skin rashes to paralysis and death. [4]

Symtoms [5]

Dysbaric osteonecrosis

Main article: Dysbaric osteonecrosis
Dysbaric osteonecrosis, also known as aseptic bone necrosis, is generally a longer term effect on the bones and joints of divers caused by decompression bubbles and may occur even if no clinical decompression sickness has been diagnosed. [6] [7]

High pressure nervous syndrome

Main article: High-pressure nervous syndrome
High-pressure nervous syndrome (HPNS) is a neurological and physiological diving disorder that results when a diver descends below about 500 feet (150 m) while breathing a helium–oxygen mixture. The effects depend on the rate of descent and the depth. The effects of HPNS comprise trembling, myoclonic jerks, drowsiness, alterations in EEG patterns, visual disruptions, queasiness, vertigo, and diminished cognitive function. [2]

Nitrogen narcosis

Main article: Nitrogen narcosis
Nitrogen narcosis is a reversible alteration in consciousness that occurs while breathing gas with a high partial pressure of nitrogen. The effect is similar to alcohol intoxication or nitrous oxide inhalation and does not usually become noticeable at nitrogen partial pressures less than about 3 bar, equivalent to a depth of about 30 meters (100 ft) on air. As depth increases, the mental impairment may become hazardous. Divers can learn to cope with some of the effects of narcosis, but it is impossible to develop a tolerance. Narcosis affects all divers breathing gas mixtures containing nitrogen, although susceptibility varies widely from dive to dive, and between individuals. One of the risks of Nitrogen narcosis is that divers may remove their regulator or fail to follow proper safety procedures.

Oxygen toxicity

Main article: Oxygen toxicity

Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen (O
2) partial pressures significantly greater than found in atmospheric air at sea level. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs and eyes.

Divers are exposed to raised partial pressures of oxygen in normal diving activities, where the partial pressure of oxygen in the breathing gas is increased in proportion to the ambient pressure at depth, and by using gas mixtures in which oxygen is substituted for inert gases to reduce decompression obligations, to accelerate decompression, or reduce the risk of decompression sickness.

They are also exposed to raised partial pressures of oxygen if given oxygen as first aid, which is a standard protocol for most acute diving related disorders, and when undergoing hyperbaric oxygen therapy in the case of decompression sickness or arterial gas embolism.

Non-dysbaric disorders associated with diving

Drowning

Main article: Drowning

"Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid". [8]

Near drowning is the survival of a drowning event involving unconsciousness or water inhalation and can lead to serious secondary complications, including death, after the event. [9] [10] Drowning is usually the culmination of a deteriorating sequence of events in a diving accident, and is seldom a satisfactory explanation for a fatality, as it fails to explain the underlying causes and complications that led to the final consequence. [11] Generally, a diver is well prepared for the environment, and well trained and equipped to deal with it. A diver should not drown merely as a result of being in the water.

Salt water aspiration syndrome

Main article: Salt water aspiration syndrome
Salt water aspiration syndrome is a rare diving disorder experienced by divers who inhale a mist of seawater from a faulty demand valve causing irritation of the lungs. [12] [13] It can be treated by rest for several hours. If severe, medical assessment is required.

Hypoxia

Main article: Hypoxia (medical)

Hypoxia is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise. A mismatch between oxygen supply and its demand at the cellular level may result in a hypoxic condition.

Generalized hypoxia occurs when breathing mixtures of gases with a low oxygen content, e.g. while diving underwater especially when using closed-circuit rebreather systems that control the amount of oxygen in the supplied air, or when breathing gas mixtures blended to prevent oxygen toxicity at depths below about 60 m near or at the surface. This condition may lead to a loss of consciousness underwater and consequent death either directly by cerebral hypoxia, or indirectly by drowning.

Latent hypoxia may occur when a breathhold diver surfaces. This is also known as deep water blackout. The consequence is likely to be drowning.

Tissue hypoxia occurs when arterial gas emboli due to either lung overexpansion injury or decompression sickness block systemic capillaries and shut off the supply of oxygenated blood to the tissues downstream. If untreated, this leads to tissue damage or death, with consequences that depend on the site and extent of the injury.

Swimming induced pulmonary edema

Main article: Swimming induced pulmonary edema

Swimming induced pulmonary edema occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli). [14]

SIPE usually occurs during heavy exertion in conditions of water immersion, such as swimming and diving. It has been reported in scuba divers, [15] [16] apnea (breath hold) free-diving competitors, [17] [18] combat swimmers, [19] [20] and triathletes. [14] The causes are incompletely understood at the present time. [14] [21] [22]

Immersion diuresis

Main article: Immersion diuresis

Immersion diuresis is a type of diuresis caused by immersion of the body in water (or equivalent liquid). It is mainly caused by lower temperature and by pressure.

The temperature effect is caused by vasoconstriction of the cutaneous blood vessels within the body to conserve heat. [23] [24] [25] The body detects an increase in the blood pressure and inhibits the release of vasopressin, causing an increase in the production of urine.

The pressure effect is caused by the hydrostatic pressure of the water directly increasing blood pressure. Its significance is indicated by the fact that the temperature of the water doesn't substantially affect the rate of diuresis. [25] Partial immersion of only the limbs does not cause increased urination.

Diuresis is significant in diving medicine as the consequent mild dehydration may be a contributing factor in the onset of decompression sickness. [26]

Hypercapnia

Main article: Hypercapnia

Hypercapnia is a condition where there is too much carbon dioxide (CO2) in the blood.

Divers may develop this condition for several possible reasons:

  • Increased work of breathing due to increased density of the breathing das with depth. [27] [28] [29] [30]
  • Inadequate ventilatory response to exertion. [27] [28] [29] [30]
  • Dead space of the breathing apparatus. [30]
  • Higher inspired CO2 due to failure of the carbon dioxide scrubber in the diver's rebreather to remove sufficient carbon dioxide from the loop.
  • Over-exertion, producing excess carbon dioxide due to elevated metabolic activity.
  • Deliberate hypoventilation, known as "skip breathing".
  • Shallow breathing, due to stress or other reasons.
  • Contamination of the breathing gas supply.
As severe hypercapnia may produce disorientation, panic, hyperventilation, convulsions, unconsciousness, and eventually death. [31] [32] it is important for divers, supervisors and life support technicians to recognise the symptoms and development of the condition in time to correct the situation.

Carbon monoxide poisoning

Main article: Carbon monoxide poisoning

Carbon monoxide poisoning occurs by inhalation of carbon monoxide (CO). Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect. Carbon monoxide is a product of incomplete combustion of organic matter due to insufficient oxygen supply to enable complete oxidation to carbon dioxide (CO2). Breathing gas for diving may be contaminated either by intake of contaminated atmospheric air, usually from internal combustion exhaust gases, or, more rarely, by carbon monoxide produced in the compressor by partial combustion of lubricants. [33]

The effects of carbon monoxide in breathing gas are increased in proportion to the depth, as the partial pressure of the contaminant is increased in proportion to the depth for a given gas fraction. The permitted levels of carbon monoxide in breathing gas for diving is lower than for at atmospheric pressure due to the concentratng effect of raised ambient pressure.[ citation needed ]

Lipid pneumonia

Main article: Lipid pneumonia
Lipid pneumonia is a specific form of lung inflammation (pneumonia) that develops when lipids enter the bronchial tree. In diving this can happen when the breathing gas supply is contaminated with lubricants from the compressor, but it is very rare. [34]

Environmental hazards

Hazards in the underwater environment that can affect divers include marine life, marine infections, polluted water, ocean currents, waves and surges and man-made hazards such as boats, fishing lines and underwater construction. Diving medical personnel need to be able to recognize and treat accidents from large and small predators and poisonous creatures, appropriately diagnose and treat marine infections and illnesses from pollution as well as diverse maladies such as sea sickness, traveler's diarrhea and malaria.

Hypothermia

Main article: Hypothermia

Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions (which is defined as 35.0 °C (95.0 °F)). Body temperature is usually maintained near a constant level of 36.5–37.5 °C (97.7–99.5 °F) through biological homeostasis or thermoregulation. If exposed to cold and the internal mechanisms are unable to replenish the heat that is being lost, a drop in core temperature occurs. As body temperature decreases, characteristic symptoms occur such as shivering and mental confusion.

Hypothermia usually occurs from exposure to low temperatures, but any condition that decreases heat production, increases heat loss, or impairs thermoregulation may contribute. [35] Heat is lost more quickly in water [36] than on land, and also more quickly in proportion to wind speed. Water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia. Divers are often exposed to low water temperatures and wind chill, which may be aggravated by evaporative cooling of wet dive suits, and mild hypothermia is not uncommon in both recreational and professional divers, while moderate to severe hypothermia remains a significant risk.

Non-freezing cold injuries

See also: Trench foot
Exposure of the extremities in water temperatures below 12°C (53.6°F) can cause permanent damage. [37]

Frostbite

Main article: Frostbite
Tissue damage by freezing of the extremities is a hazard of ice diving, mainly when the diver is on the ice after the dive, and particularly if there is wind chill.

Hyperthermia

Main article: Hyperthermia
See also: Heat stroke, Heat exhaustion, and Heat illness
Overheating may occur on the surface when the diver is preparing to dive, or on standby in heavily insulated exposure suit, or in the water, if the suit is excessively insulated for the conditions, the water temperature is too high, or the supply to a hot water suit is too hot.

Seasickness

Further information: Motion sickness

Seasickness is a form of motion sickness, a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement [38] characterized by a feeling of nausea and, in extreme cases, vertigo, experienced after spending time on a craft on water, [39] floating at the surface of a rough sea, and in strong surge near the bottom.

Seasickness can significantly reduce the ability of a diver to effectively complete a task or manage a contingency, and may predispose the diver to hypothermia and decompression sickness.

Cramps

A cramp is a sudden, involuntary, painful muscle contraction [40] or overshortening; while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affected muscle. Muscle cramps are common and are often associated with pregnancy, physical exercise or overexertion, age (common in older adults), or may be a sign of a motor neuron disorder. [41]

Cramps may occur in a skeletal muscle or smooth muscle. Skeletal muscle cramps may be caused by muscle fatigue or a lack of electrolytes such as sodium (a condition called hyponatremia), potassium (called hypokalemia), or magnesium (called hypomagnesemia [42] ). Some skeletal muscle cramps do not have a known cause. [41] Cramps of smooth muscle may be due to menstruation or gastroenteritis. Motor neuron disorders (e.g., amyotrophic lateral sclerosis), metabolic disorders (e.g., liver failure), some medications (e.g., diuretics and inhaled beta‐agonists), and haemodialysis may also cause muscle cramps. [41]

A cramp usually starts suddenly and it also usually goes away on its own over a period of several seconds, minutes, or hours.

Injury caused by marine animals

Envenomation

Main article: Envenomation
Injuries from venomous animals, which may result from skin contact with mobile or sessile cnidarians such as jellyfish and hydroids, puncture wounds caused by inadvertent impact with cryptic species such as stonefish or active defense by species such as stingrays and lionfish.

Bites

Injuries from bites usually occur when marine animals defend themselves or their territory from encroachment or perceived aggression by divers. Occasionally divers may be bitten by an animal mistaking part of the diver for food. This may occur when animals are fed by divers.

Blunt trauma

Injuries caused by impact with a large animal or part of a large animal, often apparently inadvertently, and resulting from the diver approaching closely to the animal, which may be startled, or simply proceeding on its way. This can happen when divers get too close to large sharks or cetaceans, not necessarily intentionally.

Marine microbial infection

Microbes can infect through injured skin, the mucosa, or inhalation. Nonfatal drowning in marine environments brings seawater into the lungs where the water goes through our nose or through the mouth resulting in pneumonia. Aerosolized water can contain algal toxins and can result in viruses to become airborne. [43] Infectious diseases are predominantly caused by pathogens which are viruses, bacteria, fungi and protist parasites. [44]

Contamination from polluted waters

In most places, contamination comes from a variety of sources (non-point source pollution). In a few it is primarily pollution from a single industrial source. The more immediate threat is from locations where high concentrations of toxic or pathogenic pollutants are present, but lower concentrations of less immediately harmful contaminants can have a longer term influence on the diver's health. Three major categories of contamination can cause health and safety problems for divers. These are biological, chemical and radioactive materials. [45]

The risks from hazardous materials are generally proportional to dosage - exposure time and concentration, and the effects of the material on the body. This is particularly the case with chemical and radiological contaminants. There may be a threshold limit value which will not usually produce ill effects over long-term exposure. Others may have a cumulative effect. [45]

The United Nations identification numbers for hazardous materials classifies hazardous materials under 9 categories: [45]

  1. Explosives
  2. Gases, which may be compressed, liquified or dissolved under pressure
  3. Flammable liquids
  4. Flammable solids
  5. Oxidising agents
  6. Poisonous and infectious substances
  7. Radioactive substances
  8. Corrosive substances
  9. Miscellaneous hazardous substances

A contaminant may be classed under one or more of these categories.

Poisonous substances are also classified in 9 categories: [45]

  1. Irritants
  2. Simple asphyxiants
  3. Blood asphyxiants
  4. Tissue asphyxiants
  5. Respiratory paralysers
  6. Liver and kidney toxins
  7. Substances that affect the muscles (myotoxins)
  8. Substances that affect bone marrow
  9. Substances that interfere with nerve function (neurotoxins)

Trauma due to the natural physical environment

Water movement due to waves or currents may wash the diver against hard or sharp edged obstacles, or the movement of the diver may cause impact, or unstable bottom formations may fall onto the diver, causing injury.

Injuries caused by man-made hazards

In addition to mechanisms similar to those for natural hazards, injuries caused by impact with the dive boat or other vessels or their moving parts, like propellers and thrusters, and by tools and equipment is possible. The nature of work related injury depends on the task and equipment in use.

Disorders caused by the diving equipment

A variety of disorders may be caused by ergonomic problems due to poorly fitting equipment.

Treatment

Decompression chamber Decompression chamber.jpg
Decompression chamber

Treatment of diving disorders depends on the specific disorder or combination of disorders, but two treatments are commonly associated with first aid and definitive treatment where diving is involved. These are first aid oxygen administration at high concentration, which is seldom contraindicated, and generally recommended as a default option in diving accidents where there is any significant probability of hypoxia,[ citation needed ] and hyperbaric oxygen therapy (HBO), which is the definitive treatment for most incidences of decompression illness.[ citation needed ] Hyperbaric treatment on other breathing gases is also used for treatment of decompression sickness if HBO is inadequate.

Oxygen therapy

The administration of oxygen as a medical intervention is common in diving medicine, both for first aid and for longer-term treatment.

Hyperbaric therapy

Recompression treatment in a hyperbaric chamber was initially used as a life-saving tool to treat decompression sickness in caisson workers and divers who stayed too long at depth and developed decompression sickness. Now, it is a highly specialized treatment modality that has been found to be effective in the treatment of many conditions where the administration of oxygen under pressure [47] has been found to be beneficial. Studies have shown it to be quite effective in some 13 indications approved by the Undersea and Hyperbaric Medical Society. [48]

Hyperbaric oxygen treatment is generally preferred when effective, as it is usually a more efficient and lower risk method of reducing symptoms of decompression illness, However, in some cases recompression to pressures where oxygen toxicity is unacceptable may be required to eliminate the bubbles in the tissues that cause the symptoms.

Fitness to dive

Hand held spirometer with display and transducer Handheld spirometer.jpg
Hand held spirometer with display and transducer

All divers should be free of conditions and illnesses that would negatively impact their safety and well-being underwater. The diving medical physician should be able to identify, treat and advise divers about illnesses and conditions that would cause them to be at increased risk for a diving accident.

Some reasons why a person should not be considered fit to dive are as follows:

Conditions that may increase risk of diving disorders, but are not necessarily absolute contraindications:

Conditions considered temporary reasons to suspend diving activities:

Long-term health effects of diving

Dysbaric osteonecrosis is ischemic bone disease thought to be caused by decompression bubbles, though the definitive pathologic process is poorly understood. It is a significant occupational hazard, [51] [52] which may follow a single exposure to compressed air, and may occur with no history of DCS, but is usually associated with significant compressed air exposure. [53] The distribution of lesions differs with the type of exposure - the juxta-articular lesions being more common in caisson workers than in divers. [6] [54] There is a definite relationship between length of time exposed to extreme depths and the percentage of divers with bone lesions. [2] [55] Evidence does not suggest that dysbaric osteonecrosis is a significant risk in recreational scuba diving. [53]

Exposure to increased partial pressure of oxygen during diving can raise the level of oxidative stress in which increased production of free radicals can occur. The combined influence of diving-related factors on free radical production and the long-term effects on diver resilience and health are not yet understood. Diving, and other forms of exercise, can precondition individuals for protection in further dives. It is not yet known if this preconditioning can influence resilience in other environmental extremes. [56] Cumulative exposure to high partial pressure of oxygen is known to accelerate the development of cataracts, a visual disorder that affects most people who live long enough. This is most likely in technical divers, saturation divers, and anyone who is treated with hyperbaric oxygen on several occasions.

The mortality rate in recreational diving is very low, and the risk of accidental drowning is unlikely to have a significant influence on the average life expectancy of divers. Risk of accidental drowning and other diving accidents can be reduced by following safe diving practices. [56]

Related Research Articles

<span class="mw-page-title-main">Nitrogen narcosis</span> Reversible narcotic effects of respiratory nitrogen at elevated partial pressures

Narcosis while diving is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gases at high partial pressure. The Greek word νάρκωσις (narkōsis), "the act of making numb", is derived from νάρκη (narkē), "numbness, torpor", a term used by Homer and Hippocrates. Narcosis produces a state similar to drunkenness, or nitrous oxide inhalation. It can occur during shallow dives, but does not usually become noticeable at depths less than 30 metres (98 ft).

<span class="mw-page-title-main">Decompression sickness</span> Disorder caused by dissolved gases forming bubbles in tissues

Decompression sickness is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompression. DCS most commonly occurs during or soon after a decompression ascent from underwater diving, but can also result from other causes of depressurisation, such as emerging from a caisson, decompression from saturation, flying in an unpressurised aircraft at high altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness.

<span class="mw-page-title-main">Air embolism</span> Vascular blockage by air bubbles

An air embolism, also known as a gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion injury, decompression, and a few other causes. In flora, air embolisms may also occur in the xylem of vascular plants, especially when suffering from water stress.

<span class="mw-page-title-main">Breathing gas</span> Gas used for human respiration

A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats. Oxygen is the essential component for any breathing gas. Breathing gases for hyperbaric use have been developed to improve on the performance of ordinary air by reducing the risk of decompression sickness, reducing the duration of decompression, reducing nitrogen narcosis or allowing safer deep diving.

<span class="mw-page-title-main">Oxygen toxicity</span> Toxic effects of breathing oxygen at high partial pressures

Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs, and eyes. Historically, the central nervous system condition was called the Paul Bert effect, and the pulmonary condition the Lorrain Smith effect, after the researchers who pioneered the discoveries and descriptions in the late 19th century. Oxygen toxicity is a concern for underwater divers, those on high concentrations of supplemental oxygen, and those undergoing hyperbaric oxygen therapy.

<span class="mw-page-title-main">Barotrauma</span> Injury caused by external fluid pressure

Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretching the tissues in tension or shear, either directly by an expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. Tissue rupture may be complicated by the introduction of gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with the normal function of an organ by its presence. The term is usually applied when the gas volume involved already exists prior to decompression. Barotrauma can occur during both compression and decompression events.

Decompression Illness (DCI) comprises two different conditions caused by rapid decompression of the body. These conditions present similar symptoms and require the same initial first aid. Scuba divers are trained to ascend slowly from depth to avoid DCI. Although the incidence is relatively rare, the consequences can be serious and potentially fatal, especially if untreated.

<span class="mw-page-title-main">Saturation diving</span> Diving decompression technique

Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working at great depths must undergo by only decompressing divers once at the end of the diving operation, which may last days to weeks, having them remain under pressure for the whole period. A diver breathing pressurized gas accumulates dissolved inert gas used in the breathing mixture to dilute the oxygen to a non-toxic level in the tissues, which can cause potentially fatal decompression sickness if permitted to come out of solution within the body tissues; hence, returning to the surface safely requires lengthy decompression so that the inert gases can be eliminated via the lungs. Once the dissolved gases in a diver's tissues reach the saturation point, however, decompression time does not increase with further exposure, as no more inert gas is accumulated.

In-water recompression (IWR) or underwater oxygen treatment is the emergency treatment of decompression sickness (DCS) by returning the diver underwater to help the gas bubbles in the tissues, which are causing the symptoms, to resolve. It is a procedure that exposes the diver to significant risk which should be compared with the risk associated with the available options and balanced against the probable benefits. Some authorities recommend that it is only to be used when the time to travel to the nearest recompression chamber is too long to save the victim's life; others take a more pragmatic approach and accept that in some circumstances IWR is the best available option. The risks may not be justified for case of mild symptoms likely to resolve spontaneously, or for cases where the diver is likely to be unsafe in the water, but in-water recompression may be justified in cases where severe outcomes are likely if not recompressed, if conducted by a competent and suitably equipped team.

<span class="mw-page-title-main">Diving medicine</span> Diagnosis, treatment and prevention of disorders caused by underwater diving

Diving medicine, also called undersea and hyperbaric medicine (UHB), is the diagnosis, treatment and prevention of conditions caused by humans entering the undersea environment. It includes the effects on the body of pressure on gases, the diagnosis and treatment of conditions caused by marine hazards and how relationships of a diver's fitness to dive affect a diver's safety. Diving medical practitioners are also expected to be competent in the examination of divers and potential divers to determine fitness to dive.

<span class="mw-page-title-main">Scuba diving</span> Swimming underwater, breathing gas carried by the diver

Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.

<span class="mw-page-title-main">Diver rescue</span> Rescue of a distressed or incapacitated diver

Diver rescue, usually following an accident, is the process of avoiding or limiting further exposure to diving hazards and bringing a diver to a place of safety. A safe place generally means a place where the diver cannot drown, such as a boat or dry land, where first aid can be administered and from which professional medical treatment can be sought. In the context of surface supplied diving, the place of safety for a diver with a decompression obligation is often the diving bell.

<span class="mw-page-title-main">Underwater diving</span> Descending below the surface of the water to interact with the environment

Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment. It is also often referred to as diving, an ambiguous term with several possible meanings, depending on context. Immersion in water and exposure to high ambient pressure have physiological effects that limit the depths and duration possible in ambient pressure diving. Humans are not physiologically and anatomically well-adapted to the environmental conditions of diving, and various equipment has been developed to extend the depth and duration of human dives, and allow different types of work to be done.

<span class="mw-page-title-main">Latent hypoxia</span> Lung gas and blood oxygen concentration sufficient to support consciousness only at depth

Latent hypoxia is a condition where the oxygen content of the lungs and arterial blood is sufficient to maintain consciousness at a raised ambient pressure, but not when the pressure is reduced to normal atmospheric pressure. It usually occurs when a diver at depth has a lung gas and blood oxygen concentration that is sufficient to support consciousness at the pressure at that depth, but would be insufficient at surface pressure. This problem is associated with freediving blackout and the presence of hypoxic breathing gas mixtures in underwater breathing apparatus, particularly in diving rebreathers.

<span class="mw-page-title-main">Physiology of decompression</span> The physiological basis for decompression theory and practice

The physiology of decompression is the aspect of physiology which is affected by exposure to large changes in ambient pressure. It involves a complex interaction of gas solubility, partial pressures and concentration gradients, diffusion, bulk transport and bubble mechanics in living tissues. Gas is breathed at ambient pressure, and some of this gas dissolves into the blood and other fluids. Inert gas continues to be taken up until the gas dissolved in the tissues is in a state of equilibrium with the gas in the lungs, or the ambient pressure is reduced until the inert gases dissolved in the tissues are at a higher concentration than the equilibrium state, and start diffusing out again.

Human physiology of underwater diving is the physiological influences of the underwater environment on the human diver, and adaptations to operating underwater, both during breath-hold dives and while breathing at ambient pressure from a suitable breathing gas supply. It, therefore, includes the range of physiological effects generally limited to human ambient pressure divers either freediving or using underwater breathing apparatus. Several factors influence the diver, including immersion, exposure to the water, the limitations of breath-hold endurance, variations in ambient pressure, the effects of breathing gases at raised ambient pressure, effects caused by the use of breathing apparatus, and sensory impairment. All of these may affect diver performance and safety.

<span class="mw-page-title-main">Outline of underwater diving</span> List of articles related to underwater diving grouped by topical relevance

The following outline is provided as an overview of and topical guide to underwater diving:

Investigation of diving accidents includes investigations into the causes of reportable incidents in professional diving and recreational diving accidents, usually when there is a fatality or litigation for gross negligence.

Inner ear decompression sickness, (IEDCS) or audiovestibular decompression sickness is a medical condition of the inner ear caused by the formation of gas bubbles in the tissues or blood vessels of the inner ear. Generally referred to as a form of decompression sickness, it can also occur at constant pressure due to inert gas counterdiffusion effects.

References

  1. ↑ US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006. Archived from the original on 2 May 2008. Retrieved 26 May 2008.
  2. 1 2 3 Bennett, Peter B.; Rostain, Jean Claude (2003). "The High Pressure Nervous Syndrome". In Brubakk, Alf O.; Neuman, Tom S. (eds.). Bennett and Elliott's physiology and medicine of diving (5th Rev ed.). United States: Saunders. pp. 323–57. ISBN   978-0-7020-2571-6.
  3. ↑ Campbell, Ernest (10 June 2010). "Compression arthralgia". Scubadoc's Diving Medicine Online. Retrieved 29 November 2013.
  4. ↑ Vann, Richard D., ed. (1989). "The Physiological Basis of Decompression". 38th Undersea and Hyperbaric Medical Society Workshop. 75(Phys)6–1–89: 437.
  5. ↑ "Scuba Diving: Decompression Illness & Other Dive-Related Injuries | CDC Yellow Book 2024". wwwnc.cdc.gov. Retrieved 5 August 2024.
  6. 1 2 Brubakk, Alf O.; Neuman. Tom S. (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN   978-0-7020-2571-6.
  7. ↑ British Medical Research Council Decompression Sickness Central Registry and Radiological Panel (1981). "Aseptic bone necrosis in commercial divers. A report from the Decompression Sickness Central Registry and Radiological Panel". Lancet. 2 (8243): 384–8. doi:10.1016/s0140-6736(81)90831-x. PMID   6115158. S2CID   35741112.
  8. ↑ van Beeck, E.F.; Branche, C.M.; Szpilman, D.; Modell, J.H.; Bierens, J.J.L.M. (2005), A new definition of drowning: towards documentation and prevention of a global public health problem, vol. 83, Bulletin of the World Health Organization (published 11 November 2005), pp. 801–880, archived from the original on 2 February 2008, retrieved 19 July 2012
  9. ↑ Lunetta, P.; Modell, J.H. (2005). Tsokos, M. (ed.). Macropathological, Microscopical, and Laboratory Findings in Drowning Victims. Forensic Pathology Reviews. Vol. 3. Totowa, NJ: Humana Pres Inc. pp. 4–77.
  10. ↑ Dueker, C.W.; Brown, S.D., eds. (1999). "Near Drowning Workshop. 47th Undersea and Hyperbaric Medical Society Workshop". UHMS Publication Number WA292. Undersea and Hyperbaric Medical Society: 63.
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  19. ↑ Weiler-Ravell, D.; Shupak, A.; Goldenberg, I.; Halpern, P.; Shoshani, O.; Hirschhorn, G.; Margulis, A. (1995). "Pulmonary oedema and haemoptysis induced by strenuous swimming". BMJ. 311 (7001): 361–2. doi:10.1136/bmj.311.7001.361. PMC   2550430 . PMID   7640542.
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  37. ↑ Stinton, R.T. (2006). Lang, M.A.; Smith, N.E. (eds.). "Survey of Thermal Protection Strategies". Proceedings of Advanced Scientific Diving Workshop: February 23–24, 2006. Washington, DC.: Smithsonian Institution.
  38. ↑ Benson, A.J. (2002). "35". Motion Sickness. In: Medical Aspects of Harsh Environments. Vol. 2. Washington, DC. Archived from the original (PDF) on 11 January 2009. Retrieved 9 May 2008.{{cite book}}: CS1 maint: location missing publisher (link)
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