Ask Dr. Johnson

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. 

When should a blow to the head cause concern? Should stories about head injuries like Ms Richardson’s change anything that we do in a wilderness setting?

1.  “I know someone.”  Anecdotal stories are not helpful for anyone. They make it nearly impossible to verify cause and effect let alone the details of what really happened. Deriving lessons to be learned from them is accordingly difficult. Ms. Richardson is a case and point. Follow-up stories purported to quote experts who advocated that all people sustaining a blow to the head, whether with or without loss of consciousness, are at significant enough immediate risk to warrant an evaluation by a medical professional. By extension, this means an evacuation if in a remote setting. These ideas are disingenuous and ridiculous and help no one.

2. Our position.  We believe that a blow to the head will cause an important brain injury (e.g., ones that require surgery or close hospital observation) only when impaired brain function results. Impaired brain function includes loss of consciousness (LOC), amnesia or at least a brief change in mental status including being stunned, punch drunk; lights on no one home.  Dizziness yes; seeing stars, no.

3. Concussion or TBI (traumatic brain injury)? We switched to TBI because it has become current terminology and seemed clinically based (change in brain function implied brain injury). On the other hand, the term concussion is pervasive but it is non-specific and has a variety of definitions.

4. How frequent is unlikely?  Ms Richardson developed an acute epidural hematoma (EDH), a collection of blood between the skull and the outer membrane around the brain. The frequency of this happening has been reported in 1 to 10% of all head injuries but it is not clear how head injury is defined or what the origins of these numbers are. More recent studies looking specifically at minor head trauma (LOC but awake on evaluation) of people coming to hospital are probably more helpful.  The Canadian Head Rule study reported that 0.5% had EDHs and 0.4% of all patients entered in the study required a neurosurgical procedure.(1) 2% of the patients entered in the New Orleans study had EDHs, 20% of whom required surgery.(2)  In each of these studies everyone had an LOC or something that qualified as abnormal brain function.  It would be hard to believe that the number of EDHs occurring without abnormal brain function would be higher. And not all EDHs are catastrophic, requiring surgery.

4.  Who is at highest risk?  Few people who have a TBI but wake up develop any serious sequelae requiring prompt, hospital-based intervention. Who is at the highest risk? Certainly this would include anyone with early signs of increasing intracranial pressure (ICP – persistently abnormal mental state, recurrent vomiting, worsening headache). According to the largest studies previously referenced, other important risk factors include evidence of a skull fracture (e.g., persistent leaking of blood and/or spinal fluid from the ears or nose not attributable to a local injury, large boggy scalp hematoma), high velocity/high mass impact, current use of anticoagulants/antiplatelet drugs, and age in the sixties.  Duration of LOC and pupil evaluation in an awake person were not listed as important factors. Injuries to the temple should also heighten one’s concern because its thin-walled structure makes the local arterial blood supply particularly vulnerable. According to several online references (no reliable citations given), 80+% of all EDHs occur following a fracture to the temple.

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5.  We are at least 2 hours from help.  The risk factors listed above should be helpful when a decision to evacuate poses significant risk to the rescuers and additional risk to the patient. But even a prompt evacuation of an EDH may still result in a horrible outcome because one can evolve so quickly.  An EDH in the posterior fossa (back of the skull near its base) is particularly devastating because one can present with few signs and proceed catastrophically in minutes.

Bottom line:  This is a horribly tragic story.  Even if she had developed an EDH without an apparent TBI, it would not be the basis for policies that mandate evacuations for everyone with a blow to the head.  Ultimately we know this by reading the literature and seeing real patients on a regular basis.  Despite these rare occurrences, we owe it to our students and their clients/patients to address blows to the head rationally.  Was there a TBI?  If so, the anticipated problem list includes increased ICP.  An appropriate plan is one that weighs the risks and benefits including some of the high risk factors list above.  If there is no TBI, bleeding and/or increased ICP are not going to develop.  In such a case, an urgent evacuation for further evaluation and treatment would not be warranted.  Increased ICP, on the other hand, is an emergency.  Its signs and symptoms, regardless of the cause, known or not, whether or not diagnosed as a TBI, need to be taken seriously.

If we want to practice and teach medicine, we have to accept the fact that there is no 100% or 0%.  In this case, it is a pretty safe bet.

1.  Stiell, et al.  Comparison of the Canadian CT rule and the New Orleans Criteria in patients with minor head trauma. JAMA 2005;294:1511-1518.
2.  Haydel MJ, et al. Indications for computed tomography in patients with minor head injuries. NEJM 2000;343:100-105.

PS This past week there was an article in the New England Journal of Medicine (Vol 360:1588) on the implications of the number of TBIs and subsequent post concussive syndromes being reported in the SW Asian theatre. Among other issues, the author questions the use of mild TBI instead of concussion. This is a subject worthy of more lengthy commentary.

How do I become more involved & gain experience?

Q: I’m a first year medical student at the University of Minnesota-Duluth. I am looking to become more involved in Wilderness Medicine and gain more experience.

Thanks for your help

There are a variety of ways to get involved. What is it that you would like to do? You could teach, deliver care, consult, and conduct research, locally or in other parts of the world on your own, as part of a project or during an elective.

Joining the Wilderness Medical Society (www.wms.org) is a great first step. Attending their meetings will put you in contact with other like-minded people. They and other organizations conduct medical student electives around the US and in Canada. Maybe you ought to consider trying to organize one yourself.

There are also many wonderful role models like doctors Luanne Freer and Peter Hackett. In their own ways, both have been able to take their passions for medicine and the outdoors and turn them into lifetime work.
You may not think that your school’s faculty is “…involved/interested in Wilderness Medicine” but I bet there are physiologists who are interested in the impact of environmental extremes and infectious disease specialist focused on tropical diseases and the challenges of epidemiology, prevention and treatment. These folks are always looking for people with ideas and energy.

Duluth is located in a wonderfully rich environment with a great outdoor community. You might consider connecting with a local college or university outing group, an adventure tripping company, or even ski patrol. But be patient and learn what they do and how they do it. No one wants a doctor or any other expert who is not technically proficient in the environment. All would welcome and benefit from the kind of expertise that you are trying to develop.

Perhaps your definition of wilderness medicine is not broad enough. If you are thinking in terms of problems limited to travel in the mountains, on rivers and in the woods, have a look in our FAQ section and see what we think wilderness medicine encompasses. The truth is, wilderness medicine is what you want to make of it and there are many avenues open to you. For me, it is the lack of boundaries that make wilderness medicine so exciting.

Good luck, DJ

Q: I am a camp director who requires our staff to have medical training. If they do render care, what if anything should be documented?
A medical record or any similar form of documentation is more that just an effort by medical practitioners to protect themselves against a law suit. It provides a contemporary account of what happened and what has been done. When care and transport will be lengthy, the record can provide a chronological, objective look at what you thought and did and how things have evolved.

Download SOAP pdf

We advocate recording the information in the SOAP format because it forces clarity of thought. A good SOAP note is simple to generate and results in a logical and organized document.

In the acronym, the letter S is for subjective or the story of what happened and the person’s symptoms; O is for objective things observed, felt or measured during the exam; A is for assessment of the problems/working diagnosis, what the examiner thinks is going on and could evolve over time based on S and O – this should also include the potential logistical problems of transport; P is for plan or what are you going to do about each problem. Don’t forget the logistical dilemmas. This can have a big impact on what you do and how to utilize resources.

I personally believe that a note of some kind should be made any time medical care is rendered and most particularly for those problems that will require follow-up either on the trip or afterwards. This chronology should include:

1. What happened, including a description of an accident or events leading up to the problem and the symptoms that have evolved.
2. A list of medications, allergies, and important medical problems.
3. Pertinent finding on the examination.
4. A list of what one thinks is wrong, trying to be as accurate as one can. It is more important to be clear about the urgency of a problem than about the precise diagnosis. Is this really an emergency?
5. Formulate a list of anticipated problems – how things could get worse and what new problems may evolve.
6. A plan of action and what one has actually done. Don’t forget logistics of evacuation.
7. A periodic update describing any changes in condition and/or modification in the plan.

Why bother writing all of this down? As with any other observation, the precision of one’s recollection fades over time. Taking the time to record information and then analyze it will generally clarify what is going on and lead to a better plan. When it comes to understanding what is happening and what to do about it, objectivity always trumps one’s gut. This is particularly true for relatively inexperienced practitioners.

What should you do with this information? If care is to be transferred, ideally, copy the salient points for the receiving person and retain the original for yourself (or vice versa if it will be easier). Although these kinds of notes are not legally subject to HIPPA (rules and regulations mandating how medical professionals and institutions must safeguard patient information), it is important to protect a person’s privacy. Only share patient information with healthcare providers who really need to know.

Bottom line: Record relevant information including your impression, treatment and the person’s condition over time. It is important to outline concerns for evolving problems and solutions to evacuation challenges. Be sure to limit access to this information to people who really need to know.

I’m fact-checking a piece for a national outdoor magazine. I have several questions about snake bite treatment methods:

1. Is there any benefit to the “cut-and-suck” method or should we get rid of it altogether?
2. What is your professional opinion on the effectiveness of suction devices?
3. Should a responder apply a tourniquet to a snake bite victim?
4. Should a coldpack be applied to a snake bite victim?
5. Is marking the edge of the bite to track the swelling helpful to medical personnel?

Answers:

1. No, none. In fact, it could result in an infection, impair healing and the cut could cause an unintended injury.
2. Useless. A nice study done a few years ago demonstrated their lack of efficacy. Their reputation was based on hype and not science.
3. Never a tourniquet. For some with neurotoxins, especially the most potent ones found outside of NA, a compression wrap may be helpful.
4. It will not help and could cause more injury.
5. Yes, it could be.

Remember all snakes are not the same. There are different general kinds of toxins. The management of each is directed at the damage or harm that could result