Ear pain symptoms during diving were first described by related scholars as early as 1820, and by 1873 the concept of middle ear injury related to air pressure was introduced later.

　　Diving supplies The more common ear injuries from diving are bleeding and rupture of the tympanic membrane and possible dislocation of the auditory tuberosity.

　　The resulting conductive hearing loss is mostly self-recovering.

　　Inner ear injuries caused by diving, on the other hand, cause severe permanent sensorineural hearing loss.

　　Diving and Middle Ear Pneumatic Injuries

　　The first anatomical structure to understand is called the eustachian tube, which is the channel that communicates between the tympanic chamber and the nasopharynx.

　　Under normal circumstances, the eustachian tube is closed.

　　When opening the mouth, swallowing, yawning, singing and blowing the nose, it opens momentarily to regulate the air pressure in the tympanic chamber.

　　During dive descent, the external pressure rises and is higher than the pressure in the tympanic chamber. Due to the adsorption of the mucosal surface in the eustachian tube, the tympanic chamber is relatively negative when swallowing, yawning, and puffing do not allow the gas to enter the tympanic chamber, causing the tympanic membrane to sink in.

　　The tympanic membrane has the function of buffering and compensating for pressure changes inside and outside the middle ear. When its compensatory capacity is exceeded, the tympanic membrane will become congested, causing it to rupture in severe cases and even dislocation of the auditory tuberosity.

　　When diving and rising, the pressure inside the tympanic chamber 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 can reach a balance, so the middle ear air pressure injury rarely occurs when diving and rising.

　　Diving and Inner Ear Pressure Injury

　　Inner ear pneumatic injuries caused by diving include ectolymphatic fistula and inner ear decompression sickness.

　　1. Exolymphatic fistula

　　Excessive pressure difference between ectolymphatic pressure and middle ear pressure can lead to ectolymphatic fistula in the cochlear window or vestibular window. When a diver descends, the external pressure is greater than the middle ear pressure and the diver feels stuffy in the ear and swallows or puffs to open the eustachian tube in order to balance the air pressure inside and outside the tympanic chamber.

　　When the external pressure is higher than the tympanic chamber pressure of 90 mmHg, the high air pressure compresses the eustachian tube, so when the Valsalva blowing is done forcefully, the external gas not only cannot enter the tympanic chamber, but also causes the cerebrospinal fluid pressure to rise, which can cause the vagus window membrane to rupture in the direction of the tympanic chamber, resulting in sensorineural hearing loss.

　　When the diver rises back up from the bottom, middle ear pressure is greater than the external pressure, when blowing hard, the middle ear pressure suddenly rises to compress the round window membrane, causing it to rupture in the direction of the tympanic order or bottom plate fracture in the direction of the vestibular order, causing sensorineural hearing loss.

　　During the downward dive and rise, the pressure interacts and the propagation of pressure waves leads to the rupture of the basilar membrane, vestibular membrane, balloon, ellipsoidal sac and membrane semicircular canal, causing extensive and lasting damage to vestibular function.

　　2. Inner ear decompression sickness

　　Inner ear decompression sickness is the destruction of fine membrane vagal structures by nitrogen bubbles released from the blood stream and tissues during prolonged diving out of the water.

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

　　Oxygen is involved in metabolism while diving, while nitrogen is not metabolized, but absorbed by the body's tissues. When rapidly rising out of the water, the partial pressure of nitrogen drops and nitrogen becomes bubbles diffused in the blood stream and other tissues, manifesting in light cases as fatigue and joint and muscle aches. In severe cases, the lungs, inner ear and central nervous system are damaged.

　　In the inner ear, these bubbles can mechanically rupture the membranous structures of the vagus or cause blockage of the vagal arteries, resulting in sensorineural hearing loss.

　　Prevention of diving ear pneumatic injury

　　01

　　When you have upper respiratory tract infection, do not participate in diving activities temporarily if you have nasal congestion and runny nose.

　　02

　　Diving is not recommended for people with poor eustachian tube function.

　　03

　　You should learn how to balance the middle ear pressure before diving.

　　The most commonly used method is the Valsalva maneuver, which involves pinching the nose, shutting up, and bulging the cheeks like blowing up a balloon to force the air into the eustachian tube, thereby increasing the pressure in the middle ear.

　　During the dive, especially within the first few meters and ten meters, keep doing the Valsalva action. If there is discomfort, be sure to stop the dive and maintain the depth or rise a few meters to continue to balance the middle ear pressure.

　　If you still cannot relieve it, you need to stop diving immediately.

　　04

　　Too short an interval between diving and flying may cause decompression sickness, so it is recommended to wait at least 24 hours after diving for the excess nitrogen in the body to be basically completely discharged before flying.