Drowning "Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid". 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. 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. 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 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. It canusually be treated by rest for several hours. If severe, medical assessment is required.
Hypoxia 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 Swimming-induced pulmonary edema (SIPE) occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli). SIPE usually occurs during heavy exertion in conditions of water immersion, such as swimming and diving. It has been reported in
scuba divers, apnea (breath hold)
free-diving competitors, combat swimmers, and
triathletes. The causes are incompletely understood at the present time.
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. 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. 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.
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. • Inadequate ventilatory response to exertion. •
Dead space of the breathing apparatus. • 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. 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 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. 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 concentrating effect of raised ambient pressure.
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.
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 Hypothermia is a condition in which core temperature drops below the required temperature for normal
metabolism and body functions (Clinical hypothermia is defined as below ).
Body temperature is usually maintained near a constant level of 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. Heat is lost more quickly in water 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. Clinical hypothermia (defined by a drop in core temperature below 35 °C) is unusual during the dive in scuba divers wearing reasonable thermal protection, as even a leaking dry suit reduces heat loss considerably. In deep diving, where the gas density is relatively high, the heat loss to breathing gas can be a large part of the total heat loss, and can by itself exceed the metabolic heat production, making it necessary to heat the gas supply before inhalation. The peripheral vasoconstriction that occurs when the skin is chilled does not protect against heat loss from the lungs. Helium has a lower heat capacity than nitrogen, but a higher thermal conductivity. It has several advantages as a breathing gas at high pressures, but disadvantages as an ambient atmosphere in diving bells and dry suits, where heat loss through the surrounding gas is increased.
Non-freezing cold injuries Exposure of the extremities in water temperatures below 12 °C (53.6 °F) can cause permanent damage. NFCI is a class of tissue damage caused by sustained exposure to low temperature without actual
freezing. Experimental evidence suggests a complex mode of injury with microvascular disruption, cyclic ischaemia,
reperfusion injury and direct damage to nerves due to cold.
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 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 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 characterized by a feeling of
nausea and, in extreme cases,
vertigo, experienced after spending time on a craft on
water, 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 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. 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). Some skeletal muscle cramps do not have a known cause. 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. 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 Bites Blunt trauma 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. Infectious diseases are predominantly caused by
pathogens which are
viruses,
bacteria,
fungi and
protist parasites.
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. 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. The United Nations identification numbers for hazardous materials classifies hazardous materials under 9 categories: •
Explosives •
Gases, which may be compressed, liquified or dissolved under pressure •
Flammable liquids •
Flammable solids •
Oxidising agents •
Poisonous and infectious substances •
Radioactive substances •
Corrosive substances •
Miscellaneous hazardous substances A contaminant may be classed under one or more of these categories.
Poisonous substances are also classified in 9 categories: •
Irritants • Simple
asphyxiants •
Blood asphyxiants •
Tissue asphyxiants •
Respiratory paralysers • Liver and kidney toxins • Substances that affect the muscles (
myotoxins) • Substances that affect bone marrow • 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. •
Temporomandibular joint dysfunction is pain or tenderness in the jaw, headache or facial ache caused by gripping the regulator mouthpiece between the teeth of the upper and lower jaws. This action is required to retain the mouthpiece in place for the duration of the dive, and may strain the masticatory muscles or the
temporomandibular joint, which is where the lower jawbone (mandible) hinges on the skull at the
temporal bone. This problem can be aggravated by cold water, stress, and strong water movement, and can be reduced by use of custom mouthpieces with longer and more rigid bite grip surfaces, which allow better support of the second stage with less effort. • Leg and foot
cramps may be caused by unaccustomed exercise, cold, or ill-fitting fins. •
Lower back pain may be caused by a heavy weightbelt hanging from the small of the back, counteracting the buoyancy of the diving suit which is distributed over the full length of the diver. This effect can be reduced by use of integrated weight systems which support the weights over the length of the back on the diving harness backplate. • Restricted circulation to the hands may be caused by excessively tight
dry suit cuff seals. == Treatment ==