Globally, SCUBA (“scuba”; self-contained underwater breathing apparatus) diving is the most extensively used underwater breathing system for recreation, but it also has substantial aquatic military, scientific, and commercial applications.

Although scuba diving requires skill, training, and equipment, it is considered to be a relatively low-risk activity.  Nonetheless, clinicians should be aware of some types of injuries commonly associated with undersea diving. Learn more about a few of these conditions and basic treatment strategies for affected patients.

This axial brain computed tomography (CT) scan depicts free air (arrows) in the subdural space of a navy diver who suffered right middle ear barotrauma with transient right facial palsy after a scuba dive.


Barotrauma is an injury caused by a difference in the pressure between a gas inside, in contact with, or outside the body, and that of the surrounding gas or fluid.  This condition can occur with underwater descent as well as ascent, and transpire with any collection of air that is unable to be equalized in air-containing body compartments, resulting in pain and injury

This sagital temporal bone target CT scan was obtained in the navy diver discussed on the previous slide. The tympanic segment of the right facia nerve (arrow) appears to be directly exposed to the tympanic cavity.

Barotrauma most often affects the ears on descert. As the water pressure outside the eardrums increases with the depth of the water, the diver must increase the air pressure behind the eardrums to keep them from rupturing.

Conversely, barotrauma can occur if a diver surfaces too quickly and holds their breath, which results in high pressures in the lungs. If the diver does not exhale with the changes in pressure during the ascent in the water column, the air in the lungs expands due to the decreasing surrounding pressure. Lung injury or rupture may ensue, such as pneumothorax or pneumomediastinum.

Arterial gas embolism

Arterial gas embolism is a severe, dangerous form of barotrauma in wich air is pushed into the circulation from ruptured alveoli after a rapid ascent. These large air burbbles in the circulation can travel to the brain, heart, or lungs. Arterial gas embolism causes inmediate symptoms/signs, unlike the gradual onset of those of decompression sikness ( DCS), incluiding coma paralysis, blindness, chest pain, arrhythymia, and cardiac arrest.

A diver who surfaces unconscious should be considered to be suffering an arterial gas embolism. Treatment is emergent hyperbaric  therapy as well supportive care, including administration of oxygen and intravenous (IV) fluid.

A perforated eardrum is show, 1 = tympanosclerosis, 2 = manurbrium of the malleus, and 3 = head of the stapes.

Barotrauma prevention

The most important aspect of barotrauma prevention is awareness. Divers should always be cognizant of pressure equalization in their ears, lungs, and face mask, as well as avoid potential difficulties with preessure equalization by continuosly exhaling with decreasing water depth, equalizing mask pressure concurrently with equalizing ear pressure, and not diving when suffering from sinus congestion. The use of an over-the-counter (OTC) decongestant may also help to prevent ear barotrauma.


This radiograph reveals a right chest tube (arrow) that was placed for a pneumothorax.

Batrotrauma treatment

Management of barotrauma involves treating the underlying injury. For a ruptured ear drum, if surgical repairs is not required, therapy consists of allowing the wound to heal. For a small pneumothorax, providing oxygen and inpatient hospital observation may be reasonable; however, most pneumothoraces require the placement of a tube into the thoracic cavity for decompression of the air.

The left image demostrates cutis marmorata secondary to type I DCS. The skin marbiling is outlined in red ink. Top right: Factors that affect the onset of DCS. The chest radiograph on the bottom right was obtained in another patient at the time of initiation of extracorporeal menbrane oxygenation therapy (ECMO) for pulmonary DCS.

Decompression Sickness

DCS can occur during rapid ascent from a dive when nitrogen that is pushed into the blood by the higher pressures underwater forms bubbles in blood vesseis. This situation may arise when a diver does not allow for appropriate decompression safety stops when returning to the surface.

Symptoms/signs present gradually after surfacing, ranging from mild joint pains body aches (type I) to severe neurologic symptoms (type II) such as paralysis or coma.

Initiate treatment for DCS as ason as possible. This involves administering 100% oxygen and exposing the patient back down to a high-pressure enviroment and then slowly returning them to surface air pressure. Recompression therapy allows for the body to gradually purge the blood stream of the dissolved nitrogen through the lungs, and it is most often accomplished with the use of a hyperbaric (recompression) chamber.

Nitrogen Narcosis

Nitrogen narcosis occurs when nitrogen is breathed under increased pressure. This is a depth-dependent condition: The deeper one is underwater, the more severe it becomes, Although nitrogen narcosis often takes place when divers descend below 30.5 meters (100 feet), symptoms/signs have been reported at depths of 21 meters (about 70 ft).

Nitrogen narcosis manifests with altered mental status, usually euphoria or lightheadedness that can progress to unconsciousness, as well as with impaired neuromuscular coordination. It is managed by having the diver go to a more shallow depth and allowing the symptoms to resolve.

Left: The jellyfish Olindias sambaquiensis. Right: A typical lesion from its sting in a human.

Marine Envenomation

Marine envenomations are common among undersea recreational activities, including scuba diving. Most envenomations are mild and self-limited, but several species of marine animals can cause significant morbidity and mortally, such as those belonging to the Scorpaenidae family, the most poisonous fish in the world, the Echinodermata and Cnidaria phyla as well as the Elapidae family, subfamily Hydrophlinae. Although the majority of these species are found in the Indo-Pacific region ( eg, stonefish, scorpionfish, sea snakes ), others may also be found as an invasive species in the Atlantic Ocean (eg, lionfish or turkeyfish).

Examples of stonefish (top left), scorpionfish (top right), lionfish (bottom left), and turkeysfish (bottom right) are shown.

Scorpaenidae family

The marine fish the Scorpaenidae family include the stonesfish, escorpionfish, and lionfish or turkeeyfish. They have venom gland-equipped spines that inject the venom upon contact and may break off whin the victim’s fesh. Local skin reactions and intense pain are the most commom symptoms/signs, although systemic effects (eg. Lymphadenopathy, respiratory distress, syncope, hypotension) can be life threatening.

A man suffered a pucture wound in the right middle finger from a lionfish spine. Note the presence of edema and erythema in the right hand compared to the unaffected left hand.

The key to prevention of injuries species of Scorpaenidae is avoiding contact.

Stings can often be treated with irrigation and hot water (43’5º C, 110’3º F), and the wounds should be monitored for infection. The presence of respiratory difficulty or changes in alertness should prompt immediate medical attention. Stonesfish antivenom is available in some locations.

Left: The underside of a black sea urchin, Arbacia lixula. Right: The right heel of a victim injured by numerous sea urchin spines.

Sea urchins (phylum Echinodermata)

The phylum Echidodermata includes the sea urchins, starfish, and sea cucumbers. Only a few of these organism cause envenomation of wounds in humans, including several species of sea urchins (class Echinoidea) that have spines containin venom glands.

Puncture wounds from sea urchin spines occur mainly on the hands and feet. The spines can break off in the wound and lodge in the skin, occasionally requiring surgical removal Symptoms/signs usually consist of pain, localized erythema and edema, and black discoloration at the injury site, however, severe systemic reactions may occur, including respiratory distress and  hypotension.

This image depicts localized cutaneous reactions from sea urchin envenomation.

Management of sea urchin stings involves carefully removing any protruding spines, thoroughly cleaning the affected site (s), and soaking the wound(S) in hot water (43’5 ºC, 110’3 ºF). Note that skin staining can occur in the wound channel up to 48 hours after the injury, even when no spine is retained; this is a result of residual pigment from the spines. However, if the skin discoloration persist after 72 hous, a retained spine is likely.

Main image: Dermal lesions from a jellyfish envenomation. Insect: An unspecified jellyfish.

Jellyfish (phylum Cnidaria)

The phylum Cnidaria includes calsses of jellyfish, corals, and sea anemones, all of which contain nematocysts specialized venom equipped stinging apparatuses that contain capsules, threacts, and barbs. Og these classes, some species of jellyfish are among the most well known for causing medically significant envenomation in humans worldwide.

Jellyfish are free-floating, bell-shaped organisms whose tentacles have numerous nematocysts. Triggered on contact, the nematocytsts release their venom, causin symptoms/signs as intense localized pain and linear erythematous, or vesicular lesions. Particulary toxic jellyfish such as the box jellyfish and Portuguese man-on-war can cause life-threatening systemic symptoms, including respiratory distress, hypotension, and arrhythmia.

Treatment of jellyfish stings varies depending on the species: therefore, knowledge of the organisms in a particular geographic area is advisable to optimally manage these injuries. The focus of patient care is to ameliorate the local effects, prevent further nematocyst discharges, and curb systemic manifestations.

In general, the following measures may be effective when antivenom is not available:

  • Rinse the affected areas with saltwater (Avoid freswater, as it discharges nematocysts).
  • Decontaminate the wound(s) with vinegar or lemon/lime juice over 10-15 minutes, if accesible. (A 30 second application of vinegar deactivates the nematocysts).
  • After decontamination, renove the nematocysts by coating the skin shaving cream, lotion or a similar substance, and then scraping with a razor, credit card, or the like object.
  • Provide analgesia with hot water, ice packs, and/or oral/topical pain medications.

Victims of box jellyfish stings should seek immediate medical attention, as well as decontaminate the affected area(s) with vinegar as noted above. Box jellyfish antivenom is available in some locations.

Sea snakes (Elaidae family, subfamily Hydrophiidae)

Marine snakes are only in the indian and Pacific oceans, Athough all these reptiles have extremely toxic venom that can cause weakness, paralysis, and muscle damage, most sea snake bites do not result in envenomation. The bites often only consist of 2-4 puncture wounds, with little to no local pain and edema.

When enevenomation occurs, patients may experience generalized myalgias, suphoria, and/or vomiting withn 30-60 minutes. Severe symptoms/signs include weakness, ptosis, dysphagia, dark urine, and respiratory depression.

These images ilustrate techniques for application of pressure immobilization in the field management of sea snake bites.

Bites from sea snakes require emergent, high-level medical attetion. In the field, apply pressure immobilization and elevation of the wounded limb as quickly as possible to help impede the spread of the venom. The pressure bandage should not be removed until the victim is at a medical facility with readily available antivenom and resucitation equipment.

Treatment of marine snake envenomations, as with other types of venomous snake bites, consist of administering antivenom and providing supportive care, including IV fluid, blood products, and respiratory intervention, if needed.

If no sy,ptoms are observed within 6-8 hours of the bite, it is likely a “dry bite” or a bite with no venom exposure. However, victims should not wait to seek medical care.

A male sustained a right shin laceration from contact with a coral reef, followed by a virulent variant of group A beta-hemolytic streptococcal necrotising fasclitis. Left: A dusky area of necrotic skin is over the right anterior tibia, with the central defect extended to the pretibial periosteum. A large area of erythema extended to the dorsal foot (not shown). Right: The wound was treated with a vacuum-assisted wound ciosure device. Necrotic skip lesions are present on the lateral dorsal foot.

Salt water wound care

Wounds that occur in salt water are at high risk of infection, particularly cuts and scrapes from barnacles, coral, and other ocean dwellers infection prevention measures for scuba divers include the following:

  • Scrup all wounds, with soap if available, and thoroughly rinse with fresh, clean water.
  • Dress the wounds with an antibiotic ointment and gauze wrap: change the dressing daily.
  • If antibiotic ointment or dressings are unavailable, keep the wounds clean and dry .
  • Seek medical attention in the presence of spreading erythema, drainage of pus, increasing pain, fever, and/or lymphadenophaty; antibiotics are likely needed.
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