Treating Poisonous Snakebites

In the movies, the victim of a venomous snakebite is often saved by a quick thinking companion who applies a tourniquet, cuts the skin, sucks out the poison, and spits it on to the ground. It makes for a dramatic scene, but it is not good medicine, according to an article in the New England Journal of Medicine (NEJM) on August 1, authored by physicians at the University of Maryland School of Medicine in Baltimore, and the Rocky Mountain Poison Center in Denver.

"Incision and suction as first aid measures are strongly discouraged," says Robert A. Barish, M.D., F.A.C.P., F.A.C.E.P., an emergency department physician who is associate dean for clinical affairs at the University of Maryland School of Medicine. "Following any venomous snakebite, the victim should be moved out of harm's way, and transported to the nearest medical facility as soon as possible."

"Victims of venomous snakebites require aggressive emergency medical care and if necessary, the administration of antivenom to fight the potentially fatal poison," says Barry S. Gold, M.D. F.A.C.P., clinical assistant professor of medicine at the University of Maryland School of Medicine and lead author.

"The evidence suggests that cutting and sucking, or applying a tourniquet or ice does nothing to help the victim," says Dr. Barish, a co-author of the study. "Although these outdated measures are still widely accepted by the general public, they may do more harm than good by delaying prompt medical care, contaminating the wound or by damaging nerves and blood vessels," Dr. Barish adds. The article was also co-written by Richard Dart, M.D., Ph.D., F.A.C.P., associate director of the Rocky Mountain Poison Center.

The American Association of Poison Control Centers estimates that there are 2,000 venomous snakebites every year in the United States, but because many cases go unreported, the number may be as high as 8,000, say Dr. Barish and Dr. Gold, who are recognized authorities in the treatment of venomous snakebites. Of the reported venomous snakebites each year in the U.S., five or six are fatal. Deaths typically occur in children, the elderly, or when antivenom is not given, is administered too late, or is given in insufficient doses.

Snakebites are most common in the spring and summer, when snakes are active and people are engaged in outdoor activities such as hiking or camping. The typical victim is a 17-to 27-year-old male. Most of the bites are on the upper extremities, resulting from a deliberate attempt to handle or disturb the snake. Studies have shown that alcohol intoxication is a factor in many venomous snakebites.

Of the 120 species of snakes indigenous to the United States, about 20 are venomous. Most are pit vipers such as rattlesnakes, copperheads and cottonmouths. The composition and harmful effects of the venom vary with the species, age of the snake, geographic location and time of year. Rattlesnakes and cottonmouths are more venomous than copperheads.

"Pit viper venom is a chemically complex mixture of proteins that damage blood vessels and blood cells, and can cripple the cardiovascular, respiratory, and nervous systems," says Dr. Gold, who is also a toxicology consultant to the Maryland Poison Center. Symptoms usually emerge within 30 to 60 minutes of the bite, but may be delayed for several hours. They include pain and swelling followed by nausea, vomiting and weakness. Severe symptoms include low blood pressure, difficulty breathing and shock.

The most common reaction to snakebite is fear. Many people believe that any bite from a poisonous snake will lead to illness or death. But in fact, 25 percent of all pit viper bites are "dry" and do not result in envenomation. Since the advent of antivenom, the death rate from pit viper bites has declined from five to 25 percent in the 19th century to less than one half of one percent today.

The timber rattlesnake and the copperhead are the only two venomous snakes found in Maryland. Of the three deaths attributed to snakebite in Maryland history, two were caused by bites from cobras that were owned by the victims. Cobra venom is very lethal because it attacks the central nervous system directly, causing paralysis.