Diving, Shark Trauma

Article Author:
Jeffrey Cooper
Article Editor:
Heather Murphy-Lavoie
Updated:
10/27/2018 1:33:57 PM
PubMed Link:
Diving, Shark Trauma

Introduction

There are over 470 species of sharks throughout the world. Their habitats include salt and freshwater alike. They generally prefer the shallows in temperate and tropical regions, and this is usually where divers can interact with them and consequently become the victims of shark trauma. These are the same environments that surfers are exposed. While this is a genuine threat to safety, it continues to remain statistically unlikely. Nevertheless, for those shark attacks that do occur, they become increasingly more perpetuated secondary to the level of mutilation achieved from even a singular bite. The wounds sustained from a shark bite have not been shown to follow any singular disease course or bacterial growth pattern. When shark bites do not result in death, massive blood loss, amputation, and vital organ puncture can occur. Even though sharks have not become more aggressive over the years, shark attack numbers are on the rise due to increased human interaction within the sharks’ environment.

Etiology

Sharks may attack if they perceive humans as food; although, this is thought to be uncommon and generally a case of mistaken identity, for example, mistaking a thrashing limb or reflection from diving or snorkeling gear for a smaller fish. Attacks may be provoked if a human appears to be a threat or a competitor for food (and possibly mistaken as a mating competitor). Grabbing a shark's fin or poking at it may be ill-advised. Many bites occur when sharks are handled after being caught in nets or on a finish line. Sharks may also attack to protect their territory. Although menstrual blood could theoretically attract sharks, there is no evidence of this occurrence.

Epidemiology

Worldwide, the International Shark Attack File notes 38 shark attacks on divers from 1990 through 1999. In the 10 years prior to this data, the number was 34, and approximately 20% of those attacks were fatal.[1]

Of the 470 shark species, only 30 species of sharks have been found to have attacked humans, and only 4 of the 30 species make up the majority of attacks. Sharks with the most documented attacks are the Great White shark, the Tiger shark, and the Bull shark, but the oceanic whitetip shark is believed to have the most attacks even though many of these are undocumented due to attacks occurring at sea, rather than in the coastal waters where attacks are more easily reported. Oceanic whitetip sharks are the sharks that quickly congregate around ship and airplane accidents.[2]

The scope of this problem is important. The United States is home to both the overall shark attack capital of the world (New Smyrna, Florida, although closely followed by South Africa and New South Wales) and Great White shark attack capital of the world (California). While shark attacks receive an inordinate amount of media coverage, the likelihood of being bitten by a shark in the United States is less than 1 in 11.5 million. To put this in perspective, on average, 3300 individuals drown each year in the United States, while sharks attack only around 45 people, and on average one of those people die.  Knowing the facts on shark attacks can provide insight into areas and species to avoid, and prevent becoming another statistic.

Almost half of all shark attacks are on surfers.[3]

Pathophysiology

Vibrio species are particularly prevalent in shark bites due to exposure to marine water. Other bacteria, as well as foreign material including shark teeth fragments, can be introduced in these bites. The tissue is often devitalized making infection a very serious threat. Damage to the neurovascular bundles may further dispose to considerable long-term deficits.

History and Physical

The history should include tetanus status. Physical examination will determine the extent of injuries, devitalized tissue, neurologic and vascular integrity, bony injury, and foreign bodies.

Evaluation

Radiography should be done to look for broken off pieces of shark teeth, fractures, and periosteal damage.

Treatment / Management

If there is a major injury and the patient has had significant bleeding, the initial medical care should be directed at stabilizing the ABCs (airway, breathing, and circulation). Hemorrhage control is a priority. Oxygen may be used. Intravenous lines with fluids and or blood transfusions should be started as required. If there is tissue loss, these areas need to be cleaned or debrided in the operating room by a surgeon. Hypothermia is often an issue due to time in the water, blood loss, and shock. Extremities are often injured, and if bleeding control is difficult to achieve, there should be no hesitation to use tourniquets to stop the bleeding and buy time for other stabilizing interventions. Tourniquets should be left in place until the patient can be evaluated by a surgeon who can repair an injured blood vessle. 

Isolated wounds may be able to be treated in the emergency department or a doctor's office. These wounds need to be cleaned thoroughly to prevent infection. With any wound caused by an animal bite, foreign objects can be pushed into the tissue, and these need to be identified and removed if possible. An x-ray may be used to identify such objects.

The key to preventing infections is aggressive cleaning. This can begin at the scene using tap water to clean the wound. The healthcare provider should also flush the area. Careful exploration to find foreign bodies is necessary. Devitalized tissue should undergo debridement and copious irrigation. Most injuries require surgical debridement and repair.

Prophylactic antibiotics are indicated for all shark bites, even minor bites. Vibrio should be covered. Second and third generation cephalosporins and tetracyclines are good empiric choices.[4]

Complications

Inadequate exploration can lead to a retained foreign body or retained devitalized tissue leading to infection and further tissue loss and morbidity.

Deterrence and Patient Education

Sharks may bite to eat, protect territory or as a startle reaction. In general shark attacks are rare. Helpful hints to avoiding shark attacks include:

  • Never swim or dive alone. 
  • Avoiding twilight and night diving reduces the likelihood of shark attacks.
  • Get out of the water if bleeding. Blood attracts sharks.
  • Avoid wearing shiny objects such as jewelry, bright clothing, or reflective gear.
  • Bait fishing attracts sharks. Stay out of waters where others are fishing.
  • There is increased risk if one already sees sharks present. 
  • Avoid splashing and erratic motion.
  • Do not touch sharks as this can cause an aggressive reaction.
  • Do not swim in the ocean.


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      Contributed by USPTO, Johnson, Clarence S.