ESSENTIALS OF DIAGNOSIS
Eustachian tube dysfunction and middle ear barotrauma are the 2 most common complications of scuba diving.
ET equalization is most critical while approaching close to the water surface where the greatest pressure and volume changes occur.
Inner ear barotrauma can occur via 2 mechanisms: forceful Valsalva maneuver in an attempt to equalize middle ear pressure with ET dysfunction or through increased pressure differential between the middle ear and nasopharynx, causing the ET to close.
Alternobaric vertigo is a specific type of inner ear barotrauma that occurs when there is a pressure differential causing asymmetric stimulation to the labyrinth.
Differentiation between inner ear barotrauma and decompression sickness is important to ensure proper treatment to prevent permanent sequelae.
Recreational and commercial diving are becoming more and more popular, with 900,000 certificates issued around the world annually. As of 2015, 23 million scuba diver certificates have been issued globally. The vast majority of diving-related complications are associated with the head and neck regions, with the ear being the most common site. Eustachian tube (ET) dysfunction and middle ear barotrauma are the 2 most common complications of scuba diving, with a reported incidence rate of 4.1% to 91%. Therefore, every otolaryngologist needs to understand the pathophysiology and management of barotrauma. This chapter will focus on diving medicine as it pertains to the otolaryngologist.
At sea level, our bodies are surrounded by 1 atmosphere of pressure (760 mm Hg or 1 bar). Each 33 feet (10 m) of descent in seawater adds an additional atmosphere of pressure. Pascal’s principle states that change in pressure in an enclosed fluid is transmitted equally throughout that fluid. Accordingly, because the human body is composed mainly of fluid, it is capable of tolerating pressure changes while diving. However, the air-filled spaces are not as tolerant. The volume of gas varies inversely to pressure in constant temperature according to Boyle’s law. Therefore, air-filled spaces decrease in volume when divers descend and increase upon ascending. The pressure is doubled going from sea level to 33 feet of seawater, and doubled again at only 99 feet (30 m) of seawater. Hence, the greatest pressure and volume changes occur closest to the surface.
AA. Diving medicine. Am J Respir Crit Care Med
AJ. Diving ear barotrauma. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan-2018 May 13.
Acute otitis externa (AOE) is a common condition in divers, resulting from excessive water exposure. Predisposing factors are local trauma, high-temperature and humidity exposure, and removal of the lipid from the canal skin. The most common organism of AOE is pseudomonas.