Scuba diving presents a variety of unique medical challenges for the traveling diver. Because diving injuries are generally rare, few health-care providers are trained in their diagnosis and treatment. Thus, the recreational diver must be able to recognize the signs of injury and ensure the availability of dive medicine help when needed.

Fitness to Dive

Planning for dive-related travel should take into account any changes in health status, recent injuries, or surgery. In general, respiratory disorders, as well as any disorders affecting higher function and consciousness (e.g., diabetes mellitus or asthma), psychological problems (e.g., anxiety), and pregnancy raise special concerns about diving fitness.

Diving Disorders

BAROTRAUMA

Ear and Sinus

Ear barotrauma is the most common injury in divers. On descent, failure to equalize pressure changes within the middle ear space creates a pressure gradient across the eardrum, which can cause bleeding or fluid accumulation in the middle ear, as well as stretching or rupture of the eardrum and the membranes covering the windows of the inner ear. Symptoms can include pain, ringing in the ear, vertigo, a sensation of fullness or effusion within the ear, and decreased hearing. Paranasal sinuses, because of their relatively narrow connecting passageways, are uniquely susceptible to barotraumas, generally on descent. With small changes in pressure (depth), symptoms are usually mild and short lived, but can be exacerbated by continued diving. Larger pressure changes, especially with forceful attempts at equilibration (e.g., valsalva maneuver), can be more injurious. Additional risk factors for ear and sinus barotrauma include earplugs, medications, ear and/or sinus surgery, nasal deformity and disease (1).

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

Pulmonary

Overinflation of the lungs can result as a scuba diver ascends toward the surface without exhaling. 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 one or more of three possible locations: 1) Gas entering the pleural space can cause lung collapse or pneumothorax; 2) Gas entering the mediastinum (space around the heart, trachea and esophagus) causes mediastinal emphysema and frequently tracks under the skin (subcutaneous emphysema) or into the tissue around the larynx, precipitating a change in the voice characteristics; and 3) Gas rupturing the alveolar walls can dissect into 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) (2).

While mediastinal or subcutaneous emphysema usually resolves spontaneously, pneumothorax may require specific treatment to remove the air and reinflate the lung. AGE is a medical emergency requiring appropriate intervention, which may include recompression treatment (see below).

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, 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) is an all-encompassing term that includes the dysbaric injuries, AGE and decompression sickness (DCS). Because the two 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.

Arterial Gas Embolism (AGE)

Gas entering the arterial blood through ruptured pulmonary vessels can distribute bubbles into the body tissues, including the heart and brain, where they disrupt circulation. AGE may cause minimal neurologic symptoms or dramatic symptoms that require immediate attention. These signs and symptoms include numbness, weakness, tingling, dizziness; visual blurring; chest pain; personality change; bloody froth from mouth or nose; paralysis or seizures; loss of consciousness; or death. In general, any scuba diver who surfaces unconscious or loses consciousness within 10 minutes after surfacing should be assumed to have AGE. Institution of basic life support, including the administration of 100% oxygen, is indicated, followed by rapid evacuation to a hyperbaric treatment facility.

Decompression Sickness

Breathing air under pressure causes excess inert gas (usually nitrogen) to dissolve in body tissues. The amount dissolved is depth and time related. As the diver ascends to the surface, the excess dissolved gas must be cleared via the bloodstream. Depending on the amount dissolved and the rate of ascent, some gas can supersaturate tissues where it comes out of solution to form bubbles, causing signs and symptoms of decompression sickness. These symptoms include joint aches or pain; numbness, tingling, mottling or marbling of skin; coughing spasms, shortness of breath; itching; unusual fatigue; dizziness, weakness; personality changes; loss of bowel or bladder function; staggering, loss of coordination, tremors; or paralysis; and collapse or unconsciousness (3).

Serious permanent injury may result from either AGE or DCS.

Flying After Diving

There is an increased risk of developing decompression sickness when divers are exposed to increased altitude too soon following a dive. The cabin pressure of commercial aircraft may be the equivalent of 8,000 feet (2,438.4 meters). Thus, divers should avoid flying or an altitude exposure greater than 2,000 feet (609.6 meters) for a minimum of 12 hours after surfacing from a single no-decompression dive. After repetitive dives or multiple days of diving, a diver should wait a minimum of 18 hours before ascending to altitude, to reduce the risk of decompression sickness (4). These recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will further reduce DCS risk.

Prevention of Diving Disorders

Recreational divers should dive conservatively and well within the safe limits of their dive tables or computers. Risk factors for DCI are primarily dive depth and bottom time; however, factors such as rapid ascent, repetitive dives, strenuous exercise, dives >60 feet, and altitude exposure soon after a dive also increase risk. Divers should be cautioned to stay well hydrated and rested, dive within the limits of their training, and follow established guidelines for dives unique to the travel destination. Diving is a skill that requires appropriate 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 of supplemental oxygen is considered effective first aid in relieving the signs and symptoms of decompression illness and should be administered as soon as possible. Divers are often dehydrated, either because of incidental causes, immersion, or DCI itself, which can cause a capillary leak. 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 (i.e., if the diver is conscious).The definitive treatment of DCI is recompression and oxygen administration in a hyperbaric chamber (5).

The Divers Alert Network (DAN) can be contacted by telephone at (919) 684-2948, ext. 222, or by accessing the website www.diversalertnetwork.org. DAN maintains a 24-hour emergency consultation and evacuation service at (919) 684-8111 or (919) 684-4326 (Collect calls are accepted.) DAN will provide assistance with management of the injured diver, help in deciding if recompression is needed, the location of the closest appropriate recompression facility, and assistance in arranging patient transport (6).

References

 

1. Molvaer O. Otorhinolaryngological aspects of diving. In: Bennett and Elliot’s The physiology and medicine of diving. Brubakk AO, Neuman TS, eds. 5th ed. London: Saunders; 2003:227-64.
2. Neuman TS. Arterial gas embolism and pulmonary barotrauma. In: Bennett and Elliot’s The physiology and medicine of diving. Brubakk AO, Neuman TS, eds. 5th ed. London: Saunders; 2003:557-77.
3. Moon RE. Treatment of decompression illness. In: Diving medicine, Bove AA, ed. 4th ed. London: Saunders; 2004:195-223.
4. Sheffield PJ, Vann RD. Flying after Recreational Diving Workshop Proceedings. Durham, NC, Divers Alert Network. 2004 ISBN: 0-9673066-4-7
5. Moon RE, Gorman DF. Treatment of the decompression disorders. In: Bennett and Elliot’s The physiology and medicine of diving. Brubakk AO, Neuman TS, eds. 5th ed. London: Saunders; 2003: 600-50.
6. Thalmann ED. DAN dive and travel medical guide. rev. ed. 2003. Divers Alert Network, Durham, NC.

 

DANIEL A. NORD