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Nova Southeastern University
Originally Published: Modern Resident, December/January 2015-2016
SCUBA, an acronym for self-contained underwater breathing apparatus, is a system for recreational diving practiced by hundreds of thousands of people across the world, but is not without its risks. In 2012, the incidence of SCUBA-related injuries ranged from seven to 35 per 10,000 divers and from five to 152 injuries per 100,000 dives. Insufficient training and preexisting medical conditions were common factors that played a role in injury, and drowning was the most common cause of death.[1] While risks of trauma, hypothermia and submersion injury also exist, those more specific to diving including barotrauma, decompression sickness and nitrogen narcosis will be discussed in this piece and the next.
Boyle’s law describes the relationship between pressure and volume of a system: as pressure increases (for example: descent), the volume of gas decreases. The opposite occurs during ascent. An example of this mechanism is the discomfort felt by divers and swimmers within their ears when descending and ascending in water. During descent, the increase in external water pressure causes a decrease in middle ear volume, a space enclosed by the tympanic membrane and the Eustachian tube. This causes pain in the form of middle ear squeeze or otic barotrauma, and is why divers and swimmers must frequently perform maneuvers to open their Eustachian tube. This is done by yawning, swallowing, jaw thrusting, head tilting and performing the Valsalva maneuver. For people who have trouble achieving equilibrium, advanced techniques employing a combination of moves may be necessary. Without equalization divers run the risk of tympanic membrane rupture or inner ear barotrauma leading to a perilymph fistula, which requires a referral to an otolaryngologist.
