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Monday, January 22, 2007

Bites and Stings – Snake

A pit viper snake has a heat sensing "pit" located between the nostril and eye on each side that is used to locate and trail prey. Rattlesnakes can grow up to six feet in length. Baby rattlesnakes are capable of a venomous bite from birth. Nonpoisonous snakebites are not considered serious and are generally treated as minor wounds; only poisonous snakebites are considered medical emergencies.

What are the symptoms?

Symptoms generally occur immediately, but only about one third of all bites manifest symptoms. When no symptoms occur, probably no venom was injected into the victim. In 50 percent of coral snake bites, no venom is injected because the coral snake has to chew the skin for envenomation to occur. In as many as 25 percent of all venomous pit viper bites, no venom is injected, possibly because the fangs may be injured, the venom sacs may be empty at the time of the bite, or the snake may not use the fangs when it strikes. Poisonous snakebite venom contains some of the most complex toxins known; venoms can affect the central nervous system, brain, heart, kidneys, and blood.

What are signs that indicate a poisonous snakebite include?

The bite consists of one or two distinct puncture wounds. Nonpoisonous snakes usually leave a series of small, shallow puncture wounds because they have teeth instead of fangs. The exception is the coral snake, which leaves a semicircular marking from its teeth. Because some poisonous snakes also have teeth, fang and teeth marks may be apparent. The presence of teeth marks does not rule out a poisonous bite, but the presence of fang marks always confirms a poisonous snakebite.

What are characteristics of pit viper snakes?

  • Large fangs; nonpoisonous snakes have small teeth.
  • The two fangs of a poisonous snake are hollow and work like a hypodermic needle.
  • Pupils resemble vertical slits.
  • Presence of a pit. Pit vipers have a telltale pit between the eye and the mouth. The pit, a heat-sensing organ, makes it possible for the snake to accurately strike a warm-blooded victim, even if the snake cannot see the victim.
  • A triangular or arrowhead shaped head.
  • The rattlesnake often shakes its rattles as a warning. BUT NOT ALWAYS!

One snake that is not a pit viper snake but is poisonous is the coral snake. The coral snake is highly poisonous and resembles a number of nonpoisonous snakes. Coral snakes, as proteroglyphous elapids, have fixed fangs as opposed to retractible fangs. Because its mouth is so small and its teeth are short, most coral snakes inflict bites on the toes and fingers. They have to chew the skin a while to inject venom. Coral snakes are small and ringed with red, yellow, and black. The chances for recovery of snakebite are great if the patient receives care within two hours of the bite.

How is serious the bite?

You can decide how serious the bite is by considering several factors:

  • The age, size and general health of the patient. A small child will probably react much more severely to a smaller amount of venom than will an adult. Bites are most dangerous in children and the elderly.
  • The depth, location and number of bites. A single, glancing blow by the fangs is much less dangerous than multiple wounds or wounds that penetrate the flesh deeply. A bite that penetrates a blood vessel is extremely dangerous. The least dangerous bites occur on the extremities and in fatty tissue. Bites on the head or trunk are usually fatal.
  • The duration of the bite. The longer the bite, the greater the amount of venom that may be injected into the patient's system.
  • Clothing. A snake that bites through several layers of clothing will not leave as much venom as a snake that strikes bare skin.
  • Maturity, type, and size of the snake. Small snakes usually do not produce enough venom to seriously harm an adult.
  • Condition of the fangs and venom sacs. More venom will be injected if the fangs and venom sacs are in good condition.
  • How angry or fearful a snake is. More venom will be injected if the snake is angry or fearful.

What are signs and symptoms of a pit viper bite?

The severity of a pit viper bite is gauged by how rapidly symptoms develop, which depends on how much poison was injected. Signs and symptoms of a pit viper bite include:

  • Immediate and severe burning pain and swelling around the fang marks, usually within five minutes. The entire extremity generally swells within eight to 36 hours.
  • Purplish discoloration around the bite, usually developing within two to three hours.
  • Numbness and possible blistering around the bite, generally within several hours.
  • Nausea and vomiting
  • Rapid heartbeat, low blood pressure, weakness, and fainting
  • Numbness and tingling of the tongue and mouth
  • Excessive sweating
  • Fever and chills
  • Muscular twitching
  • Convulsions
  • Dimmed vision
  • Headache

How to treat for snakebite?

The priorities of emergency care for snakebite are to maintain basic life support - airway, breathing and circulation - and limit the spread of the venom and to transport the patient without delay.

  1. Move the patient away from the snake to prevent repeated bites or bites to yourself. Snakes cannot sustain prolonged rapid movement so are often within a 20 foot radius of where the bite first occurred.
  2. Have the patient lie down and keep him quiet. Reassure him to slow the metabolism and subsequent spread of the venom.
  3. Cut and suck methods are useless. According to one study, the most you can get is six percent of the venom. Many people do far more damage when they cut than they do well.
  4. Keep the bitten extremity at the level of the heart.
  5. Remove any rings, bracelets or other jewelry that could impede circulation if swelling occurs.
  6. Clean the wound gently with alcohol, soap and water, hydrogen peroxide or other mild antiseptic.
  7. Do not cool or chill or apply ice.
  8. Do not attempt to tie any type of tourniquet or constricting bands.
  9. Transport the patient as soon as possible to the hospital. Signs and symptoms of a coral snake bite are different than those of a pit viper. Rather than leaving two distinct fang marks, the coral snake leaves one or more tiny scratch marks in the area of the bite. There is little pain or swelling and the patient's tissue usually does not turn black and blue. Usually, there is no pain or swelling at the bite site. However, one to eight hours after the bite, the patient will experience blurred vision, drooping eyelids, slurred speech, increased salivation and sweating. Emergency care for a coral snake bite is similar to that for a pit viper snake bite.

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