Posts Tagged ‘medicine’

Several times each year someone asks in class about the relative danger of an envenomation from a small versus a large crotaline (aka pit viper).  Some people are insistent that smaller snakes are more dangerous.  This idea has always felt counterintuitive to me.  The explanations seem fanciful at best.  Usually, people argue that larger (and therefore older) snakes possess some sort of volume control.  They argue that larger snakes hold back venom against humans because we are not food for them.  These larger snakes want to warn us with a strike but preserve venom for when it matters, like a meal.   I have been unable to find any science and none of the experts that I have spoken with can give a definitive answer one way or the other.  With the publication of a recent study, perhaps this theory will disappear.

This past December the Annals of Emergency Medicine published an article by Herbert and Hayes (2009; Volume 54 #6: p 831) in which they argue that a protective layer of denim over the skin may help to decrease the severity of an envenomation from a defensive strike by a southern Pacific rattlesnake. (I leave you to view the details and decide for yourselves.)   In their study, after provoking a test snake, they presented it a latex glove filled with warm water, one time bare and another time covered with a denim glove.  After a bite, they measured the venom in the water within the latex glove and, when used, on the denim glove.  The order of the trials were randomized and occurred 2 weeks apart.  They found that the amounts of venom measured were consistently and significantly greater from the larger (greater than 66 cm in length) versus the smaller (less than 55cm) snakes.

In the discussion section, they point out the volume differences as well as information from other sources that argue against the smaller is more dangerous theory.  Included are the facts that larger snakes are more likely to strike and that their strikes are more accurate.  Large snakes have longer fangs with larger hollow spaces allowing for deeper penetration and more venom flow.   They cite references (that I did not check) that claim that larger snakes cause more serious envenomations.  Herbert and Hayes state:

Thus, the more effective antipredator deterrent of bites from larger snakes may explain why they resort to biting more readily than smaller snakes.

And maybe Homo sapiens don’t learn to stand back.

Bottom Line

Although the results from this study do not definitively answer the question about size it does lend some scientific basis for debunking an unfounded belief.  Practically, of course, it does not really matter.  The anticipated problem of a venomous snake bite is an envenomation.  There is no good way to predict beforehand who will be envenomated, and if so, how bad it will be.  We treat what we see.  By the way, some skin covering, like denim, seems better than none.

There is a curious post on ems1.com’s web page today.  It relates a story about a record setting effort by a group of 8th graders in Texas.

http://www.ems1.com/ems-products/cpr/articles/605748-Texas-youths-set-record-for-worlds-largest-CPR-training-class/

No it was not a pie eating contest or sporting event.  Apparently they were certified by the Guinness folks for holding the world’s largest CPR class – 4626 students.

“As expected with thousands of junior high students, there was plenty of goofing around during the lesson. Giggling was common when they first gave their inflatable mannequins mouth-to-mouth resuscitation, and more than a few decided to head butt or slap their Mini Anne CPR dummies. But most appeared to take the lesson seriously.

Cluck (the mayor who helped organize the CPaRlington program)walked several laps around the field during the lesson, and he said most participants understood the techniques and could resuscitate someone if needed. Each student is now required to take the dummies home and teach four other people.”

Although not specifically mentioned, 30 minutes and inflatable CPR dummies sound a lot like the American Heart Association’s (AHA) CPR Anytime. Regardless of whose curriculum, I am assuming that this was not a certifying course.

The CPR Anytimeis a real departure from where the AHA was even 5 years ago.  There was a time when everyone taking one of their courses was hovered over by a hypervigilant instructor making sure that each student’s compressions and ventilations were within an upper and lower limit.  Skill testing success or failure was determined by lines on a piece of graph paper spit out from the side of the testing dummy.  Everyone knew that you had to modify your technique for the testing mannequin used, in order to pass.

Most instructors led their students to believe that if their technique varied in anyway from the norm, those efforts would hasten a patient’s demise.  Everyone assumed that the AHA knew what it was doing and as a result no one else (other than the American Red Cross and a few others) could be trusted to teach CPR.  Now these courses are more user friendly and accessible, engineered to train the masses.  These self-directed offerings are a convenient way for people to learn a skill that could enhance survivability following a cardiac arrest without having to take a course.  No one knows whether or not this new approach will make a difference.  Others of us have been allowed to use our own curricula and ideas to teach this once sacred procedure.  It seems that AHA mantra has become, do something.  Over the years, anecdotal stories suggest that an untrained person doing something is potentially beneficial and not harmful.  Science shows us that early intervention does make a difference.  I agree

Still, this rock concert-like event makes me cringe.  Why not do it right?  Is the time spent in school classrooms so valuable that they don’t have time for this or practical First Aid?   The AHA hopes people taking self-directed courses will in turn teach someone else.  Would these kids do a better job teaching their parents after a course like the one noted above or after a proper course, esepically one that utilized a variety of teaching methodolgies (e.g., fun) and was integrated in with what they are leaning in school?

This is not a criticism of these kids.  This is what they know.  Kudos to them not for the record but for the initiative and sense of civic concern.  But with a little guidance and effort, think about how much more could be done.

Summer camp and river guiding adventures are about to start!  Wilderness Medical Associates is in the thick of preparing hundreds of folks with 10 wilderness medicine courses running in the mountains of western  North Carolina.

Fay Johnson (right) and I (left) are visiting WMA sponsor camps hidden in these beautiful mountains – Falling Creek Camp, Camp Greenville, Blue Star Camp, Camp Mondamin and some other sponsors (Brevard College and Broadreach in Raleigh).  It’s such a treat to visit our awesome instructors, talk with sponsors, and soak up the youthful energy of camp counselors and outing staff.

This trip reminds me of my own wonderful camp experiences and work as a wilderness trip leader in New England.  Back in the day, we had NO wilderness medical training. Yikes!

By the end of next week, North Carolina will be a safer place because 250+ people will be newly certified in Wilderness First Aid, Wilderness Advanced First Aid, or as Wilderness First Responders.

Anne Rugg
General Manager
Wilderness Medical Associates

Sponsor Photos:

Bottom left: JJ of Camp Carolina, WMA Sponsor
Bottom right: Susan Breen of Blue Star Camps, WMA Sponsor

This question came up during our Montana WALS course last week in Red Lodge.  Richard Gates from WMI reminded the lead instructor Dr. Will Smith (and us) of a report from 2006 of an unconfirmed case.  When I googled this last evening I found out that it has in fact been confirmed.  There is an article about the case appearing this month in Toxicon. 

Why is this important?  It is a reminder that despite the rarity, these bites can be lethal (only the second in 40+ years).  Antivenin has been the treatment of choice.  The problem of course is that Wyeth has not produced that antivenin for several years.  It was scheduled for expiration in October 2008 but was extended through Oct of 2009.  Do you know what to do?  Will there be anything available other than supportive care?  Would a pressure bandage like those used in other countries on more potent neurotoxins make a difference?  Dr Norris of Stanford, the lead author, has written and lectured on snake envenomations and updated the WMS lecture series (www.wms.org) on envenomations for 2009.  He had an article published in 2005 commenting on pressure immobilization techniques and how effective lay providers are in applying one.  I look forward to reviewing the article when it arrives.  By the way, the equine Crotalidae (pt vipers) antivenin has also expired and was not extended.  Fortunately we have CroFab antivenom. 

If you are really interested in this stuff, I would suggest you try and attend Venom Week 2009 in NM starting 1 June (http://hsc.unm.edu/conf/venomweek2009/index.shtml).  It sounds like quite a line-up.  It includes one of my favourites, Rick Vetter, an entomologist who has written about spider bite misdiagnosis and arachnophobia.  I wish I could go.  If anyone reading this does attend please send us some pearls of wisdom. 

Also, check out the Miami-Dade Fire Rescue Venom Response Program(http://www.miamidade.gov/mdfr/emergency_special_venom.asp).  According to their web page they “…maintain the largest and only antivenom bank for public use in the United States.”  They have have antivenoms for a all domestic and many international species that may have been imported into the US. 

A student shares an experience that occured the day after they attended one of WMA’s Wilderness Advanced First Aid courses.

At work for a half hour. Monday morning. Phone rings, client with severe drug addictions and Borderline Personality Disorder calls. She wants to talk about not taking methadone in four days. She is speaking softly. She regularly comes on and off opiates, and while the detox is always serious, I now knew to focus on the PAS to determine what was actually life-threatening. I began asking her about her breathing which was fine, and there were no other issues for immediate death, but I did go to ins and outs, which I may not have done before the WAFA training. She reported that she hadn’t eaten since last Tuesday and vomited when she did, didn’t know when her last bowel was, hadn’t peed in at least 24 hours and didn’t remember drinking anything since some juice last night. (I later learned she was drinking alcohol up until Sunday). The flags went up for where the real problems were and I instructed her to get to the ER. She was treated for severe dehydration and electrolyte imbalance. Aside from being helpful, what I was struck by was my immediate confidence in how to handle and assess the situation. While not the most dramatic first aid story, this client can be extremely difficult to know what to do with and at least in this case I knew.

Have you had to use your skills since your course?