Monday, June 4, 2007

First Aid Update: Extract the Extractor

Did you know that a backcountry hiker is more likely to die from eating a peanut then from a rattlesnake bite? In the United States, allergic reactions to the usually tasty (but occasionally deadly) peanut are ten times more lethal than venomous snake bites. In fact, out of an estimated 8000 snake bites each year in the U.S., there are only 8 to 10 deaths. Nevertheless, many aspiring backpackers (including me) have featured snakebite preparation as an integral piece of their first aid planning.

Before hiking the Pacific Crest Trail in 2000, I became intrigued by a product called the Sawyer Extractor – a suction device designed to pull venom out of a fresh wound. The Sawyer Extractor is marketed as a cure for all sorts of bites and stings – snakes, bees, wasps, ticks, spiders, scorpions, mosquitoes, and even jellyfish. Early tests in rabbits suggested that the Extractor was an upgrade from the no-longer-recommended “cut and suck” method popularized on TV and in the movies. A search on the Internet (i.e. via my colleague “Dr. Google”) unearthed numerous corroborating testimonials. For example, Brenda in Ohio claims to have used the device after being stung by a wasp 15 times. “Within fifteen minutes,” writes Brenda, “my husband was able to extract the poison out of all of the bites and by the next morning you could not see welts or any redness, stinging or itching at all. I am definitely sold on your product!” Elsewhere on the Internet, the Extractor is touted as the only “medically recommended” first aid device for snakebites.

At the time, Brenda had me convinced that the Extractor was a promising treatment option and good insurance against a rattlesnake encounter gone awry. So, I tried to order one but, it seemed, I wasn’t the only one to have that idea - the Extractor was out of stock.

I was disappointed to begin my hike without such a seemingly indispensable tool. Today, however, I’m glad I saved myself the trouble (and the $14) of adding the Extractor to my med kit. That’s because a recent study published in the peer-reviewed medical journal Annals of Emergency Medicine has called the utility of suction devices into serious question.

In the October 2004 issue of Annals, Dr. Michael B. Alberts and his co-investigators at the Community Medical Center California in Fresno report the results of the first human trial of the Sawyer Extractor. Using hypodermic needles 1.7mm in width (equivalent to the fang of an average rattlesnake) the researchers injected a protein-rich solution attached with a radio-labeled tracer into the lower legs of eight male volunteers. Three minutes after the injection of this “mock venom” the Sawyer Extractor was applied and suction initiated. Fifteen minutes later, the Extractor was removed and its contents analyzed for radio-active counts. The investigators hypothesized that if the suction was effective, they would be able to retrieve a significant amount of the injected mock venom (measurable via the radio-active counts).

The results of the study are succinctly summarized in the title of an editorial that accompanies the paper in Annals. It reads “Snakebite Suction Devices Don’t Remove Venom: They Just Suck.” It’s unusual for medical professionals to write with such clarity, but in this case the editorial author, Dr. Sean Bush, captures the essence of the study without the clutter of medical jargon. When Dr. Alberts and colleagues analyzed the blood and fluid retrieved from the suction, they found just that – blood and fluid – with little evidence of mock venom. In fact, they only picked up an average of 38.5 out of 89,895 counts loaded. That is 0.04%, or 4 out of 10,000. Not so good. The investigators also measured mock venom load in the leg, lungs and pelvis of the volunteers after extraction and found that in the best case scenario, the Extractor might be responsible for a 2% reduction in total body venom. Still not so good.

Dr. Bush (whose name some may recognize from Animal Planet’s Venom ER) and Dr Alberts agree that there is NO evidence to support the use of the Sawyer Extractor. In fact, there might even be a danger to using the device – the suction cup has been implicated in skin damage due to excess pressure and with longer healing times.

Thus, the Extractor is not sounding indispensable any more. In fact the device is probably an unnecessary four ounce addition to a hiker’s first aid kit.

What then, should snake-wary hiker do? Unfortunately, modern medicine doesn’t have a lot advice to offer. Field treatment of venomous snake bites has become a controversial area of medical care and several proposed treatments, such as the use of tourniquets and compression isolation, have failed the tests of time and experience.

Nowadays, most emergency providers are in agreement that those that want to be prepared for the worst will need to have technology on their side. “The best first aid for snakebite,” writes Dr. Bush “is a cell phone and a helicopter.”