As early as 1820, related scholars first described the symptoms of earache while diving, and then put forward the concept of middle ear injury related to air pressure after 1873.  

 

Diving equipment Diving more common ear injuries are eardrum bleeding, rupture, auditory bone may also be dislocation.  

 

The conductive hearing loss caused by it can be recovered by itself.  

 

Injury of the inner ear caused by diving causes severe permanent sensorineural hearing loss.  

Diving and middle ear barotrauma  

 

The first thing we need to know is an anatomical structure called the eustachian tube, which connects the tympanum with the nasopharynx.  

 

In general, the eustachian tube is closed.  

 

When opening the mouth, swallowing, yawning, singing, and blowing the nose vigorously to adjust the pressure of the tympanum.  

 

When diving down, the external pressure is constantly rising, higher than the pressure inside the drum.  Due to the adsorption of mucosal surface in the eustachian tube, when swallowing, yawning and blowing can not make the gas enter the tympanum, the tympanum shows a relative negative pressure state, resulting in tympanum invagination.  

 

The tympanic membrane has the function of buffering and compensating for the changes in the pressure inside and outside the middle ear. When its compensatory ability is exceeded, the tympanic membrane will be congested, causing rupture of the tympanic membrane and even dislocation of the ossicle in severe cases.  

 

When diving up, the pressure inside the drum is higher than the external pressure. If the pressure difference reaches 20~30mmHg, the gas can break open the valve near the isthmus of the eustachian tube and enter the pharynx, so that the internal and external pressure reaches a balance. Therefore, less air pressure injury to the middle ear occurs when diving up.  

 

Diving and inner ear barotrauma  

 

Internal ear barotrauma caused by diving includes external lymphatic fistula and inner ear decompression disease.  

 

1. External lymphatic fistula  

 

Excessive difference between the external lymphatic pressure and the middle ear pressure may result in a cochlear window or vestibular window lymphatic fistula.  When the diver descends, the external pressure is greater than the pressure in the middle ear, the diver feels tightness in the ear, swallowing or blowing to open the eustachian tube, so as to balance the air pressure inside and outside the tympanum.  

 

When the external pressure is higher than the tympanum pressure of 90mmHg, the high pressure compels the eustani tube. When the external pressure is forced to Valsalva blowing, the external gas can not enter the tympanum, but causes the pressure of cerebrospinal fluid to rise, which can cause the lablabular window membrane to rupture in the direction of the tympanum, leading to sensopineural hearing loss.  

 

When the diver rises from the bottom of the sea, the pressure of the middle ear is greater than the external pressure. When blowing hard, the pressure of the middle ear suddenly rises and compels the round window membrane, making it rupture towards the direction of the typionic step or the bottom plate fracture towards the direction of the vestibular step, causing sensorineural hearing loss.  

 

In the process of diving and ascending, the pressure interaction and the propagation of pressure waves lead to the rupture of basement membrane, vestibular membrane, balloon, elliptic capsule and semicircular canal, causing extensive and lasting damage to vestibular function.  

 

2. Decompression disease of the inner ear  

 

Decompression disease of the inner ear is the destruction of the delicate membranous labyrinths by nitrogen bubbles released from the bloodstream and tissues during prolonged dives out of water.  

 

Most divers breathe compressed oxygen and nitrogen air underwater, and the deeper you dive, the higher the partial pressure of these gases in the tissues.  

 

Oxygen is involved in metabolism during diving, while nitrogen is not metabolized, but absorbed by the body's tissues. When it rises rapidly out of water, nitrogen partial pressure drops, and nitrogen becomes bubbles to disperse in the blood stream and other tissues. At best, it is manifested as fatigue and joint muscle soreness.  In severe cases, the lungs, inner ear and central nervous system are damaged.  

 

In the inner ear, these bubbles can mechanically rupture the labyrinthine structures or cause blockage of the labyrinthine arteries, causing sensorineural hearing loss.  

 

Prevention of ear barotrauma in diving  

01  

 

If you have an upper respiratory tract infection, you should not take part in diving activities for the time being.  

 

02  

 

Diving activities are not recommended for people with eustachian tube dysfunction.  

 

03  

 

Learn how to balance middle ear pressure before diving.  

 

The most commonly used method is the Valsalva maneuver, in which you pinch your nose, shut your mouth, and lift your cheeks like a balloon, forcing air into the eustachian tube, thereby increasing pressure on the middle ear.  

 

During the descent, especially in the first few and ten meters, keep performing the Valsalva. If you feel uncomfortable, stop the descent, maintain depth or rise a few meters, and continue to balance the pressure in the middle ear.  

 

If relief is still not possible, stop diving immediately.  

 

04  

 

Too short a time between diving and flight can cause decompression sickness, so it is recommended to wait at least 24 hours after diving and allow the excess nitrogen to be drained from the body before taking an aircraft.