The air-filled spaces of the middle ear have very different gas volumes, between 2.5ml and 13ml, depending on the degree of pneumatization in the temporal bone. The air in the middle ear expands as you ascend in an airplane. When the pressure difference reaches 20 m bar, the tuba (eustachian tube - the channel between the ear and the throat) opens passively and the expanding gases pass to the nasopharynx (upper part of the throat). The situation is different during descent. Due to the increase in environmental pressure, the volume of gas in the middle ear decreases.
In order for this to equalize, air must come from the nasopharynx to the middle ear. However, since the tube works like a one-way valve mechanism, air is not sent from the nasopharynx to the middle ear passively. For this, it is necessary to actively open the tuba with the help of movements such as swallowing, yawning or known pressure equalization maneuvers (Valsalva, Frenzel, etc.). In cases where pressure changes occur very quickly (jet fighter planes) the necessity of active opening of the tuba is an important issue. If this pressure equalization is not made, the pressure difference between the nasopharynx and the middle ear increases, the tube does not open anymore (tube blockage) and if the pressure difference reaches 80-120 m bar, middle and inner ear barotraumas (pressure related traumas) may occur.
Barotraumas
External auditory canal barotrauma (DKYB):Ear plug or plug used to reduce aircraft noise. It is caused by the air field formed between the membranes. During descent, the gas in this airy space shrinks. As a result, hemorrhagic blisters occur on the skin of the external auditory canal and the epithelial layer of the eardrum. External ear canal osteomas (bone protrusions) and foreign bodies are also factors that can cause DKYB.
Middle ear barotrauma (aerotitis media):Pressure equalization maneuvers to eliminate the lack of pressure in the middle ear. If it is done late, the pressure difference reaches 80-120 cc water pressure and the tuba may no longer open (tuber blockage). The frequency of opening of the tuba is 3-5 times per minute in jet fighter planes when diving, and once per minute in diving planes. It should be 5-20 times.
Another factor in the occurrence of barotrauma is the permeability level of the tuba and the condition of the epithelium and surrounding tissues around the tuba. Initially, there is retraction in the eardrum. Thus, the pressure reduction in the middle ear can be equalized to 10%. If the pressure decrease continues, hyperemia (redness) occurs first on the manubrium mallei (the area where the tiny bone called malleus adheres to the eardrum), and then on the entire eardrum. Later, hemorrhagic bullae (sacs filled with blood) are formed. Low pressure in the middle ear creates edema (swelling) in the middle ear mucosa with the suction cup mechanism, submucous hemorrhage (submucosal bleeding) is observed.
Serous and edema in the middle ear cavity. Hemorrhagic exudate (fluid and blood accumulation) occurs. Exudate may be more or less depending on the degree of negative pressure that occurs when the permeability of the vascular walls is impaired to balance the negative pressure in the middle ear. At this time, the tube opens and if the pressure equalizes, the exudate disappears. If it is left untreated and recurs frequently, it may turn into tympanosclerosis (calcification of the eardrum). The pressure difference causes the eardrum to rupture starting from 0.4-0.6 bar. Perforation (tear) is usually in the form of a line with bloody edges.
The pressure difference causes earache from 20 m bar. A feeling of fullness in the ear, buzzing, feeling of sickness, nausea, dizziness and loss of hearing are observed.
During the decrease in environmental pressure, that is, during the ascent by plane, the gases in the middle ear expand. If there is a condition (inflammation, polyp, etc.) that prevents the expanding gas in the eustachian tube from passing to the nasopharynx, the gas accumulates in the middle ear. The membrane is pushed outward. A feeling of fullness in the ear, hearing loss, earache and dizziness are observed. If there is no pathology (disease) that prevents the expanding gas in the eustachian tube from passing easily to the nasopharynx, the possibility of barotrauma during ascent is low as this transition will be made passively.
The cause of middle ear barotrauma. It lies in air pressure changes during flight. Mostly upper respiratory tract There is an acute infection. Apart from this, factors such as paranasal sinus infections, nasal polyps, allergic rhinitis (hay fever) that cause inflammation and edema in the mucosa at the mouth of the tube cause deterioration of tubular function.
Inner Ear Barotrauma (ICBT):
There is only a hypothesis for the mechanism of inner ear barotrauma. In cases of tubal dysfunction, the secondary membrane covering the round window is bulged as a result of the volatile venting of air into the middle ear violently to equalize the gas volume in the middle ear during descent, or the sudden opening of the eustachian tube during a difficult Valsalva and the sudden sending of pressurized air to the middle ear. and may rupture. This mechanism is called explosive inner ear barotrauma. Another mechanism considered is the implosiv(internal pressure) mechanism, and when a strong Valsalva maneuver is applied to open the tube, the round window becomes curved towards the middle ear and rupture may occur.
Symptoms(symptoms) sudden inner ear type hearing loss, tinnitus(ringing in the ears), vertigo (dizziness) and loss of balance.
Treatment
Prophylaxis:
Pressure equalization technique should be discussed and checked with every flyer with pressure equalization disorder. Pressure equalization maneuvers must be performed to avoid middle and inner ear barotrauma. The best prophylaxis is knowing this, and pressure equalization must be done on time and correctly.
Volatile selection also has a very important place in prophylaxis. During pilotage examinations, diseases that may prevent flight should be identified and these people should be prevented from flying.
For passengers;
it is undesirable for passengers to sleep during landing. Otherwise, the pressure difference becomes large and tubal blockage may occur. Chewing gum, taking small sips of water, and giving babies liquids from a bottle are suitable for pressure equalization. Flying should not be done in cases such as URTI, sinusitis, pharyngitis, tonsillitis. In the studies carried out, it was previously used during flight. The risk of developing barotitis is high in airline passengers who suffer from cold and sinus pain, especially in children. Valsalva maneuver is sufficient to correct the negative pressure in the middle ear in 1/3 of children and half of adults. However, if the Valsalva maneuver fails, Autovent inflation during or before the descent of the aircraft has been shown to be effective in children and adults.
Treatment of alternobaric vertigo is also prophylactic. Preventing flyers from flying in cases such as URTI, sinusitis and pharyngitis will prevent such a situation from occurring.
External auditory canal barotrauma:
Treatment of small hemorrhagic areas in the external auditory canal. It does not require. However, large hemorrhagic bullae can be drained with the help of a syringe or by incision. After the outer ear canal is cleaned with Castellani solution, a sterile cloth or weak cloth soaked with terracortril pomade is placed in the ear canal.
Middle and inner ear barotrauma:
In middle ear barotrauma; Warm application, antibiotics, anti-inflammatory, mucolytic, topical and systemic drugs with pedoephedrine are given. If there is serosity in the middle ear, it is drained by paracentesis. Flight is not allowed until tubal functions recover. In cases of chronic tubal dysfunction, a ventilation tube is placed. If the flyer does not have a hearing problem, there is no harm in flying with a ventilation tube.
In case of traumatic perforation, although it is not mandatory, the above treatment is given as a precaution and in addition, the flyer is asked not to blow his nose for a while. Large perforations are closed with myringoplasty.
If there is a suspicion of rupture, tympanotomy should be performed and the fistula should be closed.
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