Scuba Diving

Published estimates report anywhere from one-half to 4 million people who participate in recreational diving in the United States, and many travel to tropical areas of the world to dive. Divers can face a variety of medical challenges, but because dive injuries are generally rare, few clinicians are trained in their diagnosis and treatment. Therefore, the recreational diver must be able to assess potential risks before diving, recognize the signs of injury, and find qualified dive medicine help when needed.

Preparing for Dive Travel

Planning for dive-related travel should take into account any recent changes in health, including injuries or surgery, and medication use. Respiratory diseases (such as asthma or chronic obstructive pulmonary disease), disorders that affect central nervous system higher function and consciousness (such as seizures) or the peripheral nervous system (such as diabetic or autonomic neuropathy), mental health dysfunction (such as anxiety, claustrophobia, or substance abuse), cardiovascular disease that limits physical exertion, and pregnancy raise special concerns about diving fitness.

Special mention must be made regarding cardiovascular fitness. Diving should be considered a potentially strenuous activity that can make substantial demands on the cardiovascular system. People with known risk factors for coronary artery disease, including but not limited to abnormal lipid profile, elevated blood pressure, diabetes, and smoking history, who wish to either begin a dive program or continue diving should undergo a physical examination to assess their cardiovascular fitness. This may include an electrocardiogram and exercise treadmill test.

Health care workers providing travel medicine examinations for divers should also remind their patients of preventive actions they can take before a dive. Every dive should begin with identifying potential hazards (such as weather and water conditions, planned depth and bottom time, environment), assessing these hazards and the associated risk, and making decisions about acceptable risk. The diver should be able to implement controls to eliminate or reduce the risk (by using correct and well-maintained protective equipment, for example), make sure the dive is supervised, and ensure that medical care is available in the event of an emergency.

Diving Disorders


Ear and Sinus

Ear barotrauma is the most common injury in divers. On descent, failure to equalize pressure changes in the middle ear space creates a pressure gradient across the eardrum. This pressure change must be controlled through proper equalization techniques to avoid bleeding or fluid accumulation in the middle ear and avoid stretching or rupture of the eardrum and the membranes covering the windows of the inner ear. Symptoms of barotrauma include the following:

  • Pain
  • Tinnitus (ringing in the ears)
  • Vertigo (dizziness or sensation of spinning)
  • Sensation of fullness
  • Effusion (fluid accumulation in the ear)
  • Decreased hearing

Paranasal sinuses, because of their relatively narrow connecting passageways, are especially susceptible to barotrauma, generally on descent. With small changes in pressure (depth), symptoms are usually mild and subacute but can be exacerbated by continued diving. Larger pressure changes, especially with forceful attempts at equilibration (such as the Valsalva maneuver), can be more injurious. Additional risk factors for ear and sinus barotrauma include the following:

  • Use of solid earplugs
  • Medications (such as decongestants)
  • Ear or sinus surgery
  • Nasal deformity or polyps
  • Chronic nasal and sinus disease that interferes with equilibration during the large barometric pressure changes encountered while diving

A diver who may have sustained ear or sinus barotrauma should discontinue diving and seek medical attention.


A scuba diver must reduce the risk of lung overpressure problems by breathing normally and ascending slowly when breathing compressed gas. Overinflation of the lungs can result if a scuba diver ascends toward the surface without exhaling, which may happen, for example, when a novice diver panics. During ascent, compressed gas trapped in the lung increases in volume until the expansion exceeds the elastic limit of lung tissue, causing damage and allowing gas bubbles to escape into 3 possible locations:

  • Gas entering the pleural space can cause lung collapse or pneumothorax.
  • Gas entering the space around the heart, trachea, and esophagus (the mediastinum) causes mediastinal emphysema and frequently tracks under the skin (subcutaneous emphysema) or into the tissue around the larynx, sometimes precipitating a change in voice characteristics.
  • Gas rupturing the alveolar walls can enter the pulmonary capillaries and pass via the pulmonary veins to the left side of the heart, where it is distributed according to relative blood flow, resulting in arterial gas embolism (AGE).

While mediastinal or subcutaneous emphysema may resolve spontaneously, pneumothorax generally requires specific treatment to remove the air and reinflate the lung. AGE is a medical emergency, requiring urgent intervention with hyperbaric oxygen recompression treatment.

Lung overinflation injuries from scuba diving can range from dramatic and life threatening to mild symptoms of chest pain and dyspnea. Although pulmonary barotrauma is relatively uncommon in divers, prompt medical evaluation is necessary, and evidence for this condition should always be considered in the presence of respiratory or neurologic symptoms following a dive.

Decompression Illness

Decompression illness (DCI) describes the dysbaric injuries (such as AGE) and decompression sickness (DCS). Because the 2 diseases are considered to result from separate causes, they are described here separately. However, from a clinical and practical standpoint, distinguishing between them in the field may be impossible and unnecessary, since the initial treatment is the same for both. DCI can occur even in divers who have carefully followed the standard decompression tables and the principles of safe diving. Serious permanent injury or death may result from either AGE or DCS.

Arterial Gas Embolism

Gas entering the arterial blood through ruptured pulmonary vessels can distribute bubbles into the body tissues, including the heart and brain, where they can disrupt circulation or damage vessel walls. The presentation of AGE ranges from minimal neurologic symptoms to dramatic symptoms that require immediate attention. Common signs and symptoms include the following:

  • Numbness
  • Weakness
  • Tingling
  • Dizziness
  • Blurred vision
  • Chest pain
  • Personality change or difficulty thinking
  • Bloody sputum
  • Paralysis or seizures
  • Loss of consciousness

In general, any scuba diver who surfaces unconscious or loses consciousness within 10 minutes after surfacing should be suspected to have AGE. Intervention with basic life support is indicated, including the administration of the highest fraction of oxygen, followed by rapid evacuation to a hyperbaric oxygen treatment facility.

Decompression Sickness

Breathing air under pressure causes excess inert gas (usually nitrogen) to dissolve in body tissues and can saturate these tissues. The amount of gas dissolved is proportional to and increases with depth and time. As the diver ascends back to the surface, the excess dissolved gas must be cleared through respiration via the bloodstream. Depending on the amount dissolved and the rate of ascent, some gas can supersaturate tissues, where it separates from solution to form bubbles, interfering with blood flow and tissue oxygenation and causes the following signs and symptoms:

  • Joint aches or pain
  • Numbness or tingling
  • Mottling or marbling of skin
  • Coughing spasms or shortness of breath
  • Itching
  • Unusual fatigue
  • Dizziness
  • Weakness
  • Personality changes
  • Loss of bowel or bladder function
  • Staggering, loss of coordination, or tremors
  • Paralysis
  • Collapse or unconsciousness

Flying after Diving

The risk of developing decompression sickness is increased when divers are exposed to increased altitude too soon after a dive. The cabin pressure of commercial aircraft may be the equivalent of 6,000–8,000 ft (1,829–2,438 m). Thus, divers should avoid flying or an altitude exposure >2,000 ft (610 m) for:

  • ≥12 hours after surfacing from a single no-decompression dive
  • ≥18 hours after repetitive dives or multiple days of diving
  • 24–48 hours after a dive that required decompression stops

These recommended preflight surface intervals do not eliminate risk of DCS, and longer surface intervals will further reduce this risk.

Preventing Diving Disorders

Recreational divers should dive conservatively and well within the no-decompression limits of their dive tables or computers. Risk factors for DCI are primarily dive depth, dive time, and rate of ascent. Additional factors such as repetitive dives, strenuous exercise, dives to depths >60 ft (18 m), altitude exposure soon after a dive, and certain physiological variables also increase risk. Divers should be cautioned to stay hydrated and rested and dive within the limits of their training. Diving is a skill that requires training and certification and should be done with a companion.

Treatment of Diving Disorders

Definitive treatment of DCI begins with early recognition of symptoms, followed by recompression with hyperbaric oxygen. A high concentration (100%) of supplemental oxygen is recommended. Surface-level oxygen given for first aid may relieve the signs and symptoms of DCI and should be administered as soon as possible. Divers are often dehydrated, either because of incidental causes, immersion, or DCI itself, which can cause capillary leakage. Administration of isotonic glucose-free intravenous fluid is recommended in most cases. Oral rehydration fluids may also be helpful, provided they can be safely administered (for example, if the diver is conscious and can maintain his or her airway). The definitive treatment of DCI is recompression and oxygen administration in a hyperbaric chamber.

Divers Alert Network (DAN) maintains 24-hour emergency consultation and evacuation assistance at 919-684-9111 (collect calls are accepted). DAN will help with managing the injured diver, help decide if recompression is needed, provide the location of the closest recompression facility, and help arrange patient transport. DAN can also be contacted for routine, nonemergency consultation by telephone at 919-684-2948, extension 6222, or by accessing the DAN website (

Travelers who plan to scuba dive may want to ascertain whether recompression facilities are available at their destination before embarking on their trip.

hazardous marine life

The oceans and waterways are filled with creatures and, although some are capable of wounding and poisoning, most marine animals are generally harmless unless threatened. Most injuries are the result of chance encounters or defensive maneuvers. Resulting wounds have many common characteristics: bacterial contamination, foreign bodies, and occasionally venom. See the Animal-Associated Hazards section earlier in this chapter for prevention and injury management recommendations.


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  6. US Navy Diving Manual Revision 6 Change A. Publication Number SS521-AG-PRO-010 0910-LP-106-0957. 2011 [cited 2016 Mar, 16]; Revision 6 [Available from:


Daniel A. Nord, Gregory A. Raczniak