Barotrauma , also known as barotrauma, is physical damage caused to body tissues by a pressure difference between the air space within or next to the body and the gas or liquid that surrounds it. The relationship between pressure and volume is defined by Boyle’s law.
Barotrauma
Since the organism is not prepared to withstand these sudden variations in ambient pressure, it suffers an attack that is governed by simple physical laws. According to the Boyle-Mariotte law, all parts of the body that contain a mass of gas will undergo a change in volume, which will be inversely proportional to the change in pressure.
All those injuries caused in the body by the volumetric variations of the gases they contain are called barotrauma.
Barotrauma has two production mechanisms depending on the direction of the mechanical action exerted by the volumetric variations, when increasing or decreasing the volume (descents or ascents):
- Implosive Effect: It is the suction or vacuum effect, equal to a suction cup. The increase in external pressure affects the walls of the airspace, pushing them inwards. It occurs on the descent.
- Explosive Effect: It is the effect of explosion or exit to the outside. It is a consequence of the decrease in external pressure, which causes an expansion of the volume of the airspace which, if the contained air does not find an outlet, will exert pressure towards the outside. Occurs during the ascent.
Ear barotrauma
The middle ear is a narrow place with circulating air, located between the eardrum and the inner ear. The eardrum moves as a result of the vibrations of the air that comes through the external auditory canal. The movements of its membrane are transmitted to the inner ear through the movement of the bones of the middle ear. For this to happen, the air pressure must be equal on both sides of the eardrum. The pressure differences of the circulating air push the eardrum in or out. To prevent its rupture, there is the Eustachian tube, which connects the ear with the rhinopharynx, where air can enter or exit while maintaining constant pressure.
Barotrauma also affects the lungs of divers as they must adapt to the increasing pressures of descent into the water , increasing the internal pressure in the lungs to create a compensation that keeps both pressures under control. If the diver rises abruptly to the surface, that internal pressure is decompensated, potentially damaging the lungs.
Types of damage
Some examples of organs or tissues easily damaged by barotrauma are:
- Middle ear ( barotitis or aerotitis ).
- Sinuses (causing aerosinusitis)
- Lungs
- Skin (when wearing a wetsuit that creates an air gap)
- Bones (bone necrosis and temporal lobe injury)
Diving Barotrauma
During the descent, the diver experiences an increase in ambient pressure, which causes a decrease in the volume of the middle ear and the closure of the rhinopharyngeal portion of the Eustachian tube. The opening of the tube, to introduce air into the inner ear and thus equalize the pressures, can only be done with a voluntary maneuver (swallowing, Vasalva maneuver, Frenzel maneuver, etc.).
During the ascent, the diver experiences a decrease in ambient pressure, which causes a positive pressure (due to the expansion of air) inside the tympanic cage. This increased pressure causes the Eustachian tube to open automatically, allowing air to escape.
Ear problems in diving
- Barotrauma of the external ear: It occurs when water does not flood the entire external auditory canal, creating an air volume on the outside of the eardrum. It can be caused by a tight-fitting suit hood, earwax plug, or the use of rubber earplugs. During the descent, the ambient pressure increases, the pressure of the tympanic cavity also increasing as it is compensated, while the pressure within the isolated cavity becomes negative; this causes a suction of the eardrum to the outside. Being able to cause blood congestion of the skin that covers the external auditory canal, being able to also extend to the eardrum, its cure is spontaneous, without the need for treatment.
- Barotrauma of the middle ear: It is the most frequent problem, and is a consequence of a bad pressure compensation between the middle and external ear. If the pressures are not compensated, the barotrauma can be extremely serious and with irreversible consequences, being implosive or explosive. If there is, for example, a ruptured eardrum (this occurs between 1.4 and 5.7 meters in depth in a diver with a totally blocked Eustachian tube), in addition to severe pain, dizziness, buzzing and deafness may also appear . Some of these symptoms can be lifelong, depending on the severity of the barotrauma. To avoid this, equalization techniques must be used correctly during the dive,
- Barotrauma of the inner ear: Produces the rupture of the oval window or the membrane that closes the round window. The rupture will be implosive if it occurs as a consequence of a hypertension in the middle ear and explosive if it is caused by a tympanic depression or an overpressure of the labyrinthine fluids as a consequence of a violent Vasalva maneuver, or perform the Vasalva maneuver during the ascent .
- External otitis: It is the second most frequent problem of the ears of the divers. It is not a barotrauma. It is an infection of the outer ear, which can be caused by bacteria or fungi . The humid and hot conditions of this part of the body, as well as the ease of contact with pathogens suspended in the water, create the ideal conditions for this type of infection. This situation is very painful. Prevention is to keep the external ear canals dry, wax-free and wound-free. In risk situations or people with predisposition, the use of alcohol is recommended boric acid to saturation, or 2% acetic acid in propylene glycol.
- Transient vertigo. It is one of the most serious problems that can appear during the dive. It can have two different causes:
- Alternobaric vertigo. It is vertigo caused by a pressure difference between the right and left ears, it appears when one of the ears has more difficulty compensating. It can appear on the descent, but is more frequent on the ascent. It is a frequent situation when diving constipated, as one of the Eustachian tubes may have more difficulty, or even be unable to compensate. The problem can be avoided by not diving as long as the surface has minimal difficulty in compensating one of the ears. If it still happens, you must stop the ascent or descent, descend or climb one meter, fix your eyes on a defined point (the most recommended is the depth gauge).
- Vertigo due to different caloric stimuli: This type of vertigo is not related to pressure (barotrauma). It has its origin in temperature differences between the ears, it appears when the vestibular system of one ear receives a different caloric stimulus from the other ear. It can be caused, for example, by having wax in the ear canal, by a very tight hood, or even by anatomical defects.
- Transient facial paralysis: It is a paralysis on one side of the face, which appears on the rise, as a continuation of an overpressure of the middle ear on the same side. Normally it is preceded by vertigo and disappears within a maximum period of one hour. Luckily this situation is very rare, but if it occurs and lasts more than an hour, then it should be treated as a decompression sickness.
Pulmonary barotrauma
The damage in divers is generally caused by respiration and inspiration in the ascent. The underwater environment increases the pressure on the body, causing the pressure in the lungs to be greater, expanding them and can cause internal injuries. The lungs do not feel pain when they are more expanded, preventing the diver from alerting to avoid injury. The problem only occurs if a puff of compressed air is taken in depth, which then further expands lung volume upward.
Barotrauma from mechanical ventilator
Mechanical ventilation can lead to barotrauma of the lungs. This may be due to:
- The absolute pressure to be used to ventilate the lungs is not correct.
- Pressure differences associated with rapid changes in gas velocity.
The resulting alveolar rupture can lead to pneumothorax, pulmonary interstitial effusion, and pneumomediastinum.
Sinus barotrauma
The sinuses are holes in the bone mass of the skull , some of which communicate with each other and with the nasopharyngeal cavity, through small bony conduits. As in the ear, the barotraumatic problem of the sinuses is conditioned by the existence of a pathology in the ducts that communicate them.
When any of the sinuses have their drainage path blocked, whatever the cause, barotraumatic processes may appear. For the breasts, assisted compensation is very difficult. Just a stop or slow march during descent or ascent can avoid making the situation worse.
Sinus barotraumas can appear both in descent and ascent, but they are more frequent in the first case. After ear barotraumas, they are one of the most frequent affections of divers.
The most affected sinuses are usually the frontal ones, their symptoms being the appearance of violent pain when descending, or the appearance, after diving, of small amounts of blood in the goggles, a consequence of tearing in the tissue and blood vessels that line the internal cavity of the sinuses.
To avoid them you should not dive with nasal congestions caused by rhinitis, colds or sinusitis ; They can also be caused by polyps that obstruct the passage of air into the sinus, a deviated nasal septum, or the abuse of vasoconstrictors.
Gastric barotrauma
Also known as diver’s colic, its symptoms are the appearance of violent pain in the abdominal area. It is very rare. The formation of abundant abdominal gases during the dive can cause intense cramping pains during the ascent, if the entrance muscle to the stomach closes. It can appear in divers who have a predisposition to suffer from aerophagia.
Dental barotrauma
It is also another very rare barotrauma. Those teeth that are carious can be a source of discomfort for the diver by introducing or forming air bubbles inside them during the dive, and during the ascent, when expanding, they produce a compressive effect on the dental nerve, appearing a sudden and intense pain sensation.
The best prevention is good dental hygiene, with periodic check-ups, occluding all existing cavities with amalgam.
Conjunctival barotrauma
Also known as mask tackle, it occurs during descent. In order to see underwater, divers wear diving goggles, but this has created an air compartment that will be subject to the Boyle-Mariotte law, which can be the cause of barotrauma if the technique is faulty.
During the successive elevation changes that occur during a dive, a depression may form inside the mask, causing a suction effect on the part of the face that surrounds the diving mask, which will cause small epistaxis and / or conjunctival hemorrhagic suffusions that, without having any seriousness, are aesthetically spectacular.
To avoid this, it is necessary that, during the descent, air is introduced into the goggles by blowing through the nose, thus avoiding a negative internal pressure due to an increase in ambient pressure.