DAN Medical Frequently Asked Questions

Back to Medical FAQ List
Bookmark and Share

Water Sports Related Injuries

Recreational activities such as snorkeling, scuba diving, boating and beach-going are discussed in this section. Some of the risks of such activities are obvious, but some are less so. Here are factors to keep in mind when you engage in such activities.Recreational activities in, on, or near the water are extremely popular — from scuba diving to simply sitting on the beach. Some of the risks of such activities are obvious, but some are less so. Here are factors to keep in mind when you engage in such activities.

The chart lists (in increasing order of deaths) a few of the injuries that can occur during water sports — from the common but not-at-all deadly condition known as swimmer's ear; to the greatly feared but very rare phenomenon of an unprovoked shark attack; to drowning, which causes more than a third of a million deaths worldwide every year.

Worldwide, drowning is the third-leading cause of death due to unintentional injury. An estimated 372,000 people around the world die by drowning each year, accounting for about 7% of all injury-related deaths. In the United States, there are more than 3,500 unintentional drowning deaths not associated with boating (plus additional 350 boating-related drowning deaths).

Drowning is defined as respiratory impairment due to submersion in water. Although one used to hear terms such as "wet drowning" and "near-drowning," it is now recommended that those terms no longer be used. Every drowning victim should be taken to a medical facility for a thorough evaluation, no matter how trivial the episode may have seemed. Nonfatal drownings can cause serious complications.

Anyone who plans to go out onto a boat or to participate in activities near a body of water should be familiar with the factors involved in drowning and with accepted rescue and resuscitation techniques.

If drowning victims remain submerged, they eventually die from anoxia — a lack of oxygen. Drowning occurs in stages, as follows:
* Victims fight to stay afloat while hyperventilating, which may result in negative buoyancy.
* Victims submerge (drop below the surface of the water) and begin reflexively (involuntarily) holding their breath. The urge to breathe becomes stronger and stronger as victims consume all the oxygen remaining in their lungs.
* After two to three minutes, the combination of lack of oxygen and accumulation of carbon dioxide results in an uncontrollable urge to breathe; victims eventually inhale water, though usually very little.
* Victims, though now unconscious, begin to swallow water reflexively. Consequently, some drowning victims have a stomach full of water.
* More carbon dioxide accumulates, and the urge to breathe becomes even stronger. Reflexive swallowing gives way to a strong, deep breath. With the lungs then emptied of all air, victims become more negatively buoyant.
Treatment of drowning depends on restoring the victim's breathing and heartbeat via cardiopulmonary resuscitation (CPR) — or basic life support (BLS), which is another term for essentially the same procedures — and obtaining assistance promptly from qualified medical personnel. Seconds count in recovery from a drowning, and an onlooker's knowledge of CPR is often crucial.

If you are the only person present with a drowning victim and you don't know how to perform CPR, it is still beneficial to administer chest compressions — by pressing down about two inches with the heel of your hand on the center of the victim's chest, at a rate of about 100 compressions per minute, letting the chest rise fully after each compression; after every 30 compressions, stop to see if the person has started breathing again.

Learn more about CPR and essential skills.

Even if a drowning victim appears to recover, all cases of drowning should receive medical evaluation, since delayed pulmonary edema, or the accumulation of excess fluid in the lungs, is a frequent after-the-fact complication.

Risk factors for drowning include alcohol use near or in the water, medical conditions such as epilepsy, and lack of familiarity with local water hazards and features.

Prevention requires several measures. Everyone who participates in water-related activities or travels on small boats should wear a life jacket, avoid alcohol, learn CPR, and never swim unattended.

The sections below list popular water sports and the injuries most commonly associated with each.Snorkeling is swimming while using a mask and snorkel and sometimes other equipment, too, like a wetsuit or fins. Typically, snorkelers stay just below the water's surface, but they may make breath-hold dives to lower depths. In contrast to scuba diving, which is generally perceived as a dangerous activity that requires training and involves regulation, snorkeling is considered innocuous. As a result, most snorkelers do not receive proper training. In addition, few people pursue snorkeling seriously; most get involved with the sport on an opportunistic basis, without much planning or forethought. It's possible to get into snorkeling on your own or through a resort recreation program. But such programs typically just rent snorkeling equipment and take snorkelers to interesting areas but don't offer much in the way of instruction, assistance, or emergency preparedness. Often, no pre-participation health screening is required, or if one is conducted it's done ad hoc by nonmedical personnel.

The major risk for snorkelers is drowning; it can occur as a result of sudden cardiac arrest, immersion pulmonary edema, hypoxic blackout, water inhalation, being struck by a watercraft, strong water movement due to tides or currents, and other mishaps.

Sudden cardiac arrest and immersion pulmonary edema can affect any swimmer but are more likely to occur in people with pre-existing medical conditions — especially hypertension (high blood pressure) and heart disease — and in older people. Learn more about cardiovascular risk factors.

Hypoxic blackout — a loss of consciousness due to lack of oxygen — can be caused by protracted breath-holding underwater. Average healthy young people can typically hold their breath for one to two minutes while resting on the surface; older people and those unaccustomed to physical activity generally have less breath-holding capability. Exercise significantly reduces anyone's breath-holding capability, because exertion causes the body's tissues to burn more oxygen. This means the duration of a breath-hold is much shorter while you're swimming underwater, especially if you're a weak or inefficient swimmer. The warning sign that termination of a breath-hold should be imminent is an urge to breathe caused by the accumulation in the body of a critical level of carbon dioxide. In some individuals, however, this urge can be very weak. It can also be postponed by repeated deep and fast breathing (hyperventilation) before submersion. Voluntary hyperventilation reduces the level of carbon dioxide in your blood. As a consequence, it takes longer to reach a critical level of carbon dioxide — but during that extended time, your oxygen levels continue to drop, and unconsciousness can occur without the natural warning sign. To reduce the risk of hypoxic blackout, snorkelers are advised not to practice hyperventilation unless they are assisted by a capable fellow diver. And even in the best circumstances, hyperventilation should be limited to two deep breaths before submersion.

Another snorkeling problem is water inhalation, which can occur due to difficulty holding the snorkel in place or due to wave action. Dental issues may also contribute to water inhalation. The sudden inhalation of water can cause coughing, uncontrolled breathing, laryngospasm (an involuntary spasm of the muscles that control the "windpipe," or larynx), flooding of the lungs with water, or the development of a cardiac arrhythmia — any of which can render a snorkeler unconscious and result in drowning.

Being struck by a watercraft is not uncommon for snorkelers (or swimmers) in high-traffic areas. Snorkelers should stay within protected areas, visibly marked, and even so should still pay attention to the boat traffic around them.

Strong water movement — waves or currents — can also overcome snorkelers, sweep them out to the sea, tow them under the surface, or throw them onto rocks. Snorkelers should always seek information about local water conditions and hidden hazards. Swimming in remote and unpopulated areas by novice snorkelers is strongly discouraged.Diving can be an inspiring and enjoyable recreational activity, but a wide array of diving disorders can afflict the individual who dives without taking proper precautions. This guide will touch briefly on the two primary such disorders — decompression illness and barotrauma — plus a couple of other concerns, since DAN offers numerous other publications that cover diving disorders in considerable detail.

Decompression illness (DCI): There are two forms of DCI — decompression sickness (DCS) and arterial gas embolism (AGE).
DCS, a condition popularly known as "the bends," is one of the main hazards associated with compressed-gas diving. When a diver is breathing in an environment of elevated pressure, such as when scuba diving, inert gases like nitrogen move into the body's tissues and dissolve there. Your body's absorption of these inert gases (a process known as uptake) increases progressively with the depth and length of your dive. The longer you stay at depth, the more inert gases accumulate in your body. Then, when you ascend toward surface, the pressure decreases and the gas starts leaving your tissues. That is why a diver's ascent must be controlled, to allow for the orderly elimination (or "washout") of the accumulated gases, as they're transported by your blood to your lungs and exhaled. A slow ascent, conducted either continuously or in stages, usually allows for safe decompression, while a too-rapid ascent can result in the development of gas bubbles in your tissues and sometimes in symptoms of DCS.

The symptoms of DCS primarily reflect the effects of the gas bubbles in whichever tissues are directly affected. The condition's secondary effects can compromise the function of a broad range of tissues, further jeopardizing the affected diver's health. Signs and symptoms of DCS include mild to moderate musculoskeletal pain and mild cutaneous (skin) sensory changes. More severe symptoms include neurological deficits (such as weakness in the lower extremities), an abnormal gait, vertigo, altered mental function and cardiopulmonary instability. Learn more about decompression sickness.

AGE, on the other hand, is characterized by rapidly advancing neurologic symptoms following a dive. Often, AGE is a consequence of a rapid ascent to the surface while deliberately holding the breath — something that may happen when a diver goes into panic mode. Certain medical conditions that cause intrapulmonary air trapping (the retention of excess air in the lungs), such as asthma or chronic obstructive pulmonary disease, can also increase the risk of AGE.

The appearance of any of these symptoms following a dive should prompt immediate attention and a call for assistance — including to DAN. Administering oxygen, checking the victim's hydration status, and arranging for evacuation are among the matters that must be attended to.

Barotrauma: Barotrauma is an injury caused by a differential in pressure between the ambient environment — whether on the surface or underwater — and an air-filled space in the body such as, most commonly, the middle ears and the sinuses. It is possible, however, to have barotrauma of the lungs, and there are rare cases of dental and gastrointestinal barotrauma. Symptoms of barotrauma include vertigo (dizziness), respiratory distress, and cardiovascular instability. Barotrauma can be prevented by proper equalization — adjustment of your middle ear or sinus pressure to the ambient pressure by any of several techniques that force air through your auditory tubes.

Other concerns: It is also important for scuba divers to understand the effects of the various gases involved in respiration on the body:
* Nitrogen: A condition called nitrogen narcosis, popularly referred to as "the martini effect" can result from breathing nitrogen at the higher partial pressure of compressed air — which increases with increased depth. It is characterized by an altered mental state that has been likened to mild intoxication — hence the term "martini effect."
* Carbon dioxide: If the level of carbon dioxide in the body becomes elevated due to exertion, incomplete exhalation, or breath-holding, it can result in dyspnea (difficulty breathing), headache, or an altered level of consciousness.
* Oxygen: Hypoxia, or lack of oxygen, can cause loss of consciousness, while elevated levels of oxygen can result in seizures. The latter effect can be intensified by elevated carbon dioxide levels, immersion, or exercise. Strict attention to oxygen levels, especially at maximum diving depths, is essential.
* Carbon monoxide: Carbon monoxide — a highly poisonous, odorless, colorless gas — is a product of incomplete combustion that can be found, for example, in exhaust from the engines of improperly ventilated boats; it can occasionally be introduced into scuba tanks if they are carelessly filled. Symptoms of carbon monoxide poisoning initially include headache, nausea, and fatigue and can progress to dizziness, seizures, respiratory arrest, and even death. If it is suspected, first aid should include the administration of supplemental oxygen.
It is also important for divers to understand the implications of flying (or driving to a high elevation) soon after diving. The lower pressure in an aircraft cabin or at altitude may cause decompression illness in previously asymptomatic divers or worsen existing symptoms. Divers without any postdive DCI symptoms may use these guidelines for flying in an unpressurized aircraft at altitudes of 2,000 to 8,000 feet (610 to 2,438 meters) or in a pressurized aircraft cabin:
* For a single no-decompression-stop dive, a minimum preflight surface interval of 12 hours is suggested.
* For multiple dives per day or multiple days of diving, a minimum preflight surface interval of 18 hours is suggested.
* For dives requiring decompression stops, there is little evidence on which to base a recommendation; therefore, a preflight surface interval longer than 18 hours appears prudent.
Note, however, that these suggested preflight surface intervals do not guarantee that a diver will avoid DCI — and longer surface intervals will further reduce the risk.Boating is a very popular recreational activity. In 2014, there were an estimated 11.8 million registered vessels in the United States alone. Most boats stay in domestic coastal or inland waters, but a certain number sail abroad. Boating involves hazards associated with the vessel itself, as well as with its destination. Boaters who undertake long, oceangoing voyages are most at risk, as they may be isolated and out of reach of any help in case of emergency. Boaters who anchor in remote destinations that are uninhabited or lacking EMS services similarly need to be self-reliant. Emergencies that such intrepid travelers must be ready to face include a range of acute illnesses and injuries that threaten life, limb or function.

In the U.S. alone, in 2014, the Coast Guard received reports of 4,064 boating accidents involving 2,678 injuries and 610 deaths. The fatality rate is 5.2 deaths per 100,000 registered recreational vessels. The causes of recreational boating deaths are listed in the table below.

Drowning caused 78 percent of these boating deaths, and 80 percent of the boaters who drowned were on a vessel less than 21 feet in length. Most victims were not wearing a life jacket. Capsizing and falling overboard were common accidents that resulted in death. Alcohol use was the leading known contributing factor in fatal boating accidents (it was identified in 21 percent of the deaths). Other contributing factors were operator inattention, improper lookout, operator inexperience, and excessive speed.

If an emergency occurs during offshore sailing, it's important to have some means of communication with either other vessels or the shore, to alert rescuers. Sometimes, however, it's impossible to establish a connection, making the chance of a rescue slim. In such cases, survival at sea depends on many factors, but in general it's shorter than on land. Thus it is very important that any search and rescue start as soon as possible. Many boaters file so-called "float plans," just as pilots file flight plans. Float plans are not filed with the Coast Guard, or its equivalent in other countries, but with a friend or relative. The intention is if anything should happen while a boat is at sea, then that person knows where to start searching for it if it's overdue.

Boaters must be well prepared and equipped for a range of medical emergencies. DAN offers a suite of first-aid courses and a variety of medical kits. For offshore sailing, boaters must meet international regulations, as well as country-specific requirements at all their ports of call and at their final destination. For further information, call DAN (+1-919-490-2011) or a boating organization.

Finally, a reminder to all boaters to watch for swimmers and divers while you're under way!Despite their often-pristine look, beaches can harbor a number of health hazards — especially very popular beaches, beaches in densely populated areas, and beaches in developing countries. For example, walking barefoot on a beach may expose you to injuries from washed-ashore debris, needles used by drug addicts, pet waste, and parasitic, bacterial or viral infections.

Swimming may well involve further hazards. Water pollution typically increases after big rains, because they can result in sewage backups and spills into coastal waters, leading to increased concentrations of disease-causing bacteria that may be swallowed with seawater. Many viruses, bacteria and other microbes can survive for some time in seawater, so swimming should be avoided after a big rain. There's no guarantee that clear-looking water is sanitary, but if water looks murky, the risks are certainly greater. The spectrum of possible swimming diseases includes hepatitis, diarrhea, Legionnaire's disease, swimmer's ear, conjunctivitis, and even methicillin-resistant Staphylococcus aureus (MRSA).

If you plan to spend time at a beach, especially if you plan to swim, check out this useful app developed by the U.S. Centers for Disease Control and Prevention (CDC):

Healthy Swimming: Getting ready to go swimming? Don't leave home without the CDC's Healthy Swimming app!

Help keep yourself and your family healthy and safe this summer swim season. If you are a pool inspector, operator or lifeguard, have the latest information at your fingertips to answer patron questions. We all share the water we play and swim in. Learn about the germs that we all bring into the places we swim, how they could make you and others sick, and how you can take a few easy and effective steps to help protect yourself and others.

This app will tell you about:
* How we benefit from swimming. Did you know swimming can improve your health — and your mood?
* Where we swim. Did you know germs could be lurking anywhere you swim or play in the water, even in the pool down the street?
* What's in the water. Did you know chlorine and other disinfectants don't kill germs instantly? How to stay healthy and safe. Healthy and safe swimming is easy with CDC's simple tips!

Other Features FAQs