EMS World

AUG 2011

EMS World Magazine is the most authoritative source in the world for clinical and educational material designed to improve the delivery of prehospital emergency medical care.

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Page 64 of 71

| By Drew Wohl, EMT-B, DMT EMERGENCIES Understanding concepts related to diving will prove valuable in case of emergency Scuba diving encompasses a wide range of interests and a variety of participants, including recreational divers who enjoy touring the reefs and looking at marine life, commer- cial divers who work in underwater construction, and public safety divers who perform search and rescue opera- tions. Diving emergencies present unique issues for EMS providers, so having a general understanding of concepts related to diving will be valuable in the event you ever need to respond to the scene of a diving emergency. Overview of Gas Laws Before discussing diving emergen- cies, let’s look at how certain gas laws relate to diving emergencies.1 Boyle’s Law states that gas volume is inversely proportional to pressure. A familiar example can be found in the release of a balloon into the air. As the balloon ascends, the pressure on the outside of the balloon is reduced, the air inside it expands and the balloon will eventually burst. If the balloon is taken underwater, it will get smaller. Boyle’s Law also explains why you may feel pain in your ears during take-off and landing when flying. A diver is subject to this same compression and expansion of air, which can lead to barotraumas or pressure injuries. Dalton’s Law provides that each gas in a gas mixture contributes a portion of the total pressure exerted by the entire gas mixture. Reducing pressure basically makes air “thinner.” For example, the air pressure in Denver is lower than in New York, which is part of the reason why New York athletes may have trouble catching their breath in Denver. Henry’s Law provides that increased pressure on a gas will force gas into a liquid; decreased pressure will cause gas to be released from a liquid. When you open a soda, the pressure on the soda is reduced and results in “fi zzing” as bubbles are released from the liquid. Similarly, gas forced into and released from tissue while diving forms the basis of decompression sickness or “the bends.” Diving Emergencies When a diver enters the water, his body responds to the change in tempera- ture, including reducing peripheral blood flow to maintain core temperature. The reaction may also include a gasp for breath, which could escalate into hyper- ventilation and drowning. Immersion can cause arrhythmias leading to syncope or death. Death is rare from the initial immersion, but if an emergency devel- oped at the beginning of a dive, a reac- tion to initial immersion should be kept in mind.2 GENERAL ENVIRONMENTAL CONSIDERATIONS Although divers take steps to keep warm while diving, heat loss will occur. Divers on vacation often make multiple dives per day and subject themselves to prolonged cooling over the course of the day. Further heat loss (and gain) can occur as divers are exposed to the sun or wind between dives.3 EMSWORLD.com | AUGUST 2011 61 Photos by Drew Wohl

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