Contradictions and precautions

Diving-related disorders

Contradictions and precautions

Serious diseases

Diving is a sport for everyone who is healthy and in good form. Moreover, the modern equipment makes diving easier and more accessible for various people. However, there are certain diseases that prevent from diving. These include:

- high blood pressure (hypertension),

- diabetes,

- ischemic heart disease (myocardial ischemia),

- considerable obesity,

- asthma bronchiale,

- susceptibility to pneumothorax (pulmonology),

- epilepsy,

- perforation of the eardrum.

Trivial afflictions

It is also advisable to plan diving according to the disposition just before the trip. Even cold, cough, dehydration, chill or hangover may lead to serious problems under the water. It is better to delay diving for the next day than to risk your health.

Dental problems

Every potential diver should check their teeth before diving, especially if they have had a root canal work, crowns or fillings. If one wants to avoid a tooth blow out on ascent, a visit at the dentist’s is obligatory. Just as the air spaces in the middle ear and sinuses, the air spaces in incompletely solid teeth can be dangerous on descent or ascent. Health and solid teeth don’t compress when descending or ascending. But every forgotten hole in the tooth, a badly fitted crown a poorly fitted filling may cause extreme pain when ascending. Under the water, the pressurised air can get into a tooth cavity, then get trapped in the tooth and expand on ascent pressing every nerve in that tooth. Braces and orthodontic treatments (everything outside the teeth, away from the nerves) aren’t the barriers for diving.

Diving-related disorders



Serious medical problems are not very common in scuba diving. However, every diver should be aware of the potential problems that may occur.

Trivial disorders

The most common medical problem is a simple middle ear squeeze which causes pain in the diver’s ear. As in the case of the teeth, the reason here is also pressure (the pressure under water is considerably higher than above water). To be more specific, the difference in pressure between the air spaces in the ear and mask and higher water pressure when descending. Inner ear or sinuses squeezes are less common. Diving in cold water can be dangerous and lead to hypothermia (dangerously low body temperature).

Another problems that may occur underwater are cuts, scrapes, bites, stings and other injuries from many fish species and other marine fauna. One have to watch out for the wrecks, old anchors, fishing lines, any sharp pieces of metal and even old ammunition that can be found at the sea bed.

Dangerous disorders

Medical problems listed below are serious and if any of the symptoms occur while diving or after, it is urgent to seek medical care immediately.


The serious diving-related disorders can result either from expansion or compression of air spaces in the body – barotrauma, or can result from dissolved nitrogen in the body – decompression sickness.


Barotrauma occurs to air spaces in the body on ascent or descent because while gases are compressible, the tissues are not. When the ambient pressure increases, the internal air spaces aren’t able to support the tissues to resist the higher external pressure. When the ambient pressure decreases, the gas of the higher pressure in the internal air spaces can get tapped and cause damage to the tissues. Barotrauma can cause damage to: middle ear, sinuses, lungs, eyes and skin.

Air embolism (Gas embolism)

This is a very serious type of barotrauma that is caused by bubbles that enter the bloodstream and block the flow of oxygen and blood to the brain and other vital organs. Bubbles can also cause clots in blood vessels. It can happen on rapid ascent when breathing inappropriately. It can cause a risk of drowning or even lead to death within minutes.

    The symptoms include:

    - sudden loss of consciousness,

    - itchy skin,

    - numbness,

    - weakness,

    - seizures,

    - partial paralysis,

    - coughing up blood,

    - chest pain, shortness of breath,

    - confusion,

    - agitation,

    - headache.

    The symptoms of air embolism are similar to these of decompression sickness or a stroke.

    The treatment is particularly the same as in the case of decompression sickness – recompression carried out in a hyperbaric unit. First aid with a use of closed-circuit rebreathers can be useful in order to deliver oxygen to a diver.

Ear barotrauma

This is a type of barotrauma that can occur to a diver when the Eustachian tube (connection between the middle ear and the back of the nose and upper throat) is blocked. Then equalizing the air pressure on both sides of the eardrum is impossible and as a result the air pressure in the middle ear is different than outside the eardrum.

    The symptoms include:

    - ear discomfort,

    - ear pain,

    - hearing loss,

    - “clogging” of the ear,

    - tinnitus (ringing in the ear),

    - feeling of pressure in the ear,

    - dizziness,

    - bleeding from the ear or the nose.


    Ear barotrauma can affect the outer, middle or inner ear and the treatment is different for these types. For outer ear barotrauma, the ear canal has to be cleared. For middle ear barotrauma, the treatment can include decongestants (oral or nose spray), antihistamines or steroids. Also antibiotics can be recommended by a doctor in order to prevent ear infection. For inner ear barotrauma, the hospitalization and bed rest are necessary.

Pulmonary barotrauma

This type of barotrauma is caused by the expansion of air held in the lungs due to decreasing pressure when a diver is ascending. The compressed air that is breathed at depth, underwater, contains more molecules than “normal” air at the surface. When pressure decreases, air expands and its volume increases. When a diver fills his lungs with the compressed air and doesn’t breathe it out freely on ascent, there is twice as much air in the lungs (the lungs are overinflated). It usually happens in a hurry, when a diver is running out of air and tries to get to surface. Some bubbles from the overinflated lungs can enter the bloodstream and lead to air embolism. Another complication may be a collapsed lung.

    The symptoms include:

    - chest pain,

    - shortness of breath,

    - hoarseness,

    - pneumothorax (collapsed lung).

  The treatment is particularly the same as in the case of air embolism and decompression sickness – recompression carried out in a hyperbaric unit. First aid with a use of closed-circuit rebreathers can be useful in order to deliver oxygen to a diver.

Decompression sickness (DCS)

Decompression sickness (often called “the bends”, the diver’s disease) occurs on a rapid ascent  (or without carrying out decompression stops) when a diver experiences a decrease in the pressure around the body. The excess of gases, especially nitrogen, (inhaled at higher pressure) stored in body tissues and blood comes out of physical solution (outgassing) and forms bubbles in the blood.


There are some factors that can make decompression sickness more likely to occur:

- the larger pressure reduction, the more likely decompression sickness

- frequent dives (for example several dives within 24h)

- fast ascents.

Some reports also indicate that age, previous joint or limb injuries, high body fat content or alcohol consumption can create higher risk of decompression sickness.

    The symptoms are most frequently noticeable in the shoulders, elbows, knees and ankles. The symptoms include:

    - swelling,

    - muscle, joint (“the bends”) and tendons pain,

    - paralysis,

    - problems of the sensory system,

    - chest pain,

    - cough,

    - shortness of breath,

    - itchy skin and rashes.

    Decompression sickness can even lead to death.

    The treatment is recompression carried out in a hyperbaric unit. First aid with a use of closed-circuit rebreathers can be useful in order to deliver oxygen to a diver.

Decompression illness (DCI)

Decompression illness occurs when the ambient pressure around the body decreases, for example on ascent. Also long or deep dives, cold water, too much exertion underwater, and rapid ascents increase the risk of decompression illness. Generally, decompression illness is caused by decompression sickness and air embolism.


Depending on the seriousness of DCI the symptoms may be not obvious or very severe. They include:

- sensation disorders,

- pain,

- dizziness,

- weakness,

- breathing problems,

- unconsciousness.


If the symptoms are not severe, the first step is to collect a complete diving history and to seek help in the nearest medical facility. If a diver suffers from pain due to DCI, they need to be treated with 100% oxygen and taken to the nearest medical facility. Divers with severe symptoms should also be treated with oxygen and taken to the hospital. The further treatment of dehydration and maintaining blood pressure must be given only by trained professionals. After stabilization the diver needs treatment in a hyperbaric unit. Treatment of unconscious divers should begin with cardiopulmonary resuscitation.

Breathing gas disorders



Hypoxia is the condition that can occur when the tissues do not get enough oxygen. It can be caused by an interruption of the gas supply, or when breathing gas mixture with a low amount of oxygen. A risk of hypoxia increases when using closed-circuit rebreathers (if the oxygen sensor or the airflow rate mechanism fails). When hypoxia occurs, brain is at the most risk but it can also result in multiple organ failure (insufficient level of oxygen obstructs proper cell function). If not noticed on time, hypoxia leads to unconsciousness, or death.


    The symptoms include:

    - headache,

    - lack of concentration,

    - lack of muscle control,

    - drowsiness,

    - agitation,

    - blackout,

    - seizures.


    Immediate treatment for hypoxia should start in the water. The diver has to shift to gas containing sufficient oxygen. At the surface, patients with mild symptoms require oxygen therapy. Hypoxic patients with serious symptoms need hospitalization. They should receive supportive treatment aimed mainly at attaining normal arterial oxygen and carbon dioxide level. Treatment may include mechanical ventilation.


Hypoxemia is caused by the prolonged reduction of the oxygen concentration in the arterial blood (not only in the tissues). It starts with gasping, hyperventilation, and is followed by intentional stop of breathing and laryngospasms.
Hypoxemia may lead to hypoxemic hypoxia.


    The symptoms include:

    - heavy breathing,

    - lightheadedness,

    - euphoria,

    - fatigue,

    - chest pain,

    - seizures,

    - loss of consciousness.



    The only effective way to counteract hypoxemia is the oxygen therapy.



Hypercapnia (or hypercarbia), carbon dioxide poisoning, occurs when the level of carbon dioxide in blood exceeds 45 mmHg. Hypercapnia can result from various causes such as skip breathing (holding breath intentionally), over-excersising (increased carbon dioxide production), inadequate ventilation of rebreather (poorly functioning scrubber), or failure of carbon dioxide absorbing. Generally, it is the problem with exhaling and removing carbon dioxide. Hypercapnia is often associated with the use of long snorkels, full-face masks, and rebreathers due to large dead air spaces. It can limit work capacity and diver’s safety. It may also lead to central nervous system oxygen toxicity or decompression illness.


    The symptoms include:

    - headache,

    - confusion,

    - accelerated breathing due to raised blood pressure,

    - shortness of breath,

    - loss of consciousness.


    The first thing in overcoming hypercapnia is to lower the level of the inhaled carbon dioxide by shifting to an alternate gas supply, increasing the ventilation, or decreasing the level of exertion. The dive should be stopped if the problem is caused by defective equipment.

Carbon monoxide poisoning


Carbon monoxide poisoning is an uncommon problem when diving. It can occur when the air in the cylinder is contaminated or as a result of a defective air compressor. Tolerable level of carbon monoxide is lower than at the surface due to the increase in partial pressure. Carbon monoxide poisoning may have fatal consequences in such a hazardous environment as at depth.


    The symptoms include:

    - agitation,

    - dizziness,

    - headache,

    - breathless,

    - confusion,

    - weakness,

    - unconsciousness.


    Divers who suffer from carbon monoxide poisoning should be treated with 100% oxygen at the surface (e.g. via a nonbreather mask). Divers with serious symptoms (e.g. severe headache, neurological symptoms) need hyperbaric oxygen therapy.

Oxygen toxicity


Oxygen toxicity is a physiological damage resulting from elevated partial pressure of oxygen. There are two types of oxygen toxicity that affect the lungs and airways or the central nervous system. Pulmonary (“chronic”) oxygen toxicity results from long exposures to partial pressure of oxygen higher than 0.5 atmospheres. Central nervous system (“acute”) oxygen toxicity typically occurs when the partial pressure of oxygen reaches 1.6 atmospheres. The risk of oxygen toxicity increases with cold, exertion and hypercapnia.


    The symptoms of oxygen toxicity include:

    - muscular twitching in the face,

    - constricted vision,

    - rining/whistling sound in the ears,

    - nausea,

    - dizziness,

    - convulsions,

    - loss of unconsciousness.


    Divers who have symptoms of oxygen toxicity should decrease the depth 3 meters and switch to gas supply with lower content of oxygen. If convulsions occur, the diver also should switch to gas of lower oxygen content. The depth should maintain constant unless an ascent is necessary. Unconscious divers should be treated in the recompression chamber.

Nitrogen narcosis


Nitrogen narcosis (also called rapture of the deep) results from high partial pressure of nitrogen. It typically occurs when the partial pressure of nitrogen is 3 bar (three times greater than atmospheric pressure). Nitrogen inhaled at high concentrations can reduce diver’s neurological abilities.


    The symptoms include:

    - loss of judgement,

    - lack of concern for safety,

    - slowed response time,

    - euphoria,

    - hallucinations,

    - loss of sensation of lips, gums, and legs.


    In order to counteract the nitrogen narcosis, the partial pressure of nitrogen must decrease. The diver should be taken to the surface or to a shallower depth.

A diver can prevent the disorders if he or she remembers about: proper training, good health, equipment in good order, slow ascent and descent, decompression stops, decongestants before diving, flying without 24h break after diving and the nearest hyperbaric unit address.