Wilderness Medicine

Classroom Medicine

Tod Schimelpfenig — Mon, 07 May 2012 22:52:00 GMT

I recently sat through a wilderness medicine class by a well-meaning instructor who, despite decent credentials, had never cared for anyone in the wilderness. This is just after reading a poorly crafted wilderness medicine text. Instead of listening to the talk I made a list of things that drive me nuts in wilderness medicine education.

At the top of the list is classroom medicine. These are tools, techniques and advice that work in a clean, controlled world and fail in the reality of the field. Years ago we taught, I taught, not to apply warmth to a severely hypothermic patient because they were in "a stable metabolic icebox." Then I knelt next to my first severely hypothermic patient and the shallowness of this advice was clear. I had no illusions I would warm this patient in the field, but not applying heat to stabilize his temperature made no sense. I read advice to keep frozen feet frozen all night by keeping the foot outside a sleeping bag. This fell to the axe of reality when I stared at my own frozen foot in a tent on a cold winter's night. We used to think tourniquets implied amputation and that open chest wounds need to be sealed with three-sided dressings to allow air to escape. This classroom advice did not survive the test of the battlefield. If your skepticism meter is pegging over words of dubious wisdom, ask the instructor if he has ever done this to a real patient. You'll be surprised how often the honest answer is no.

High on my list are inaccurate statements of frequency. If I believed all the tales of drama I hear from someone who heard from someone who heard, I would not leave home without an auto- injector of epinephrine in a hip holster, locked and loaded. If I believed the NOLS incident data history, solid enough to generate multiple medical papers, I can argue that anaphylaxis is rare in the wilderness. But I won't make that argument. A snapshot is not the entire picture. Data is often a matter of context. We don't know the true incidence of anaphylaxis, or many other ailments, in the outdoors. Statements of frequency need to be viewed with healthy skepticism.

In the same vein I recently read that the risk of a lawsuit from reducing a dislocation in the field is high. Based on what cases or data? I've heard outdoor experts say that the most common injury on NOLS courses is a laceration from slicing cheese. The real answer, sprains and strains, is easily accessible in the published literature. When you see or hear numbers, ask for the source, and ask for the conflicting evidence. If the educator is worth his salt he will tell you the breadth of science on this question and why he choose to believe this particular study. Consider any unreferenced number to be junk.

I'm also skeptical of resumes, credentials and endorsements. Resumes can be exercises in creative writing, exaggerating or underselling experience. Credentials often tell us of educational accomplishments, not experience. Endorsements might be earned, but they can also be purchased-- a source of income for an organization willing to sell their name. These badges don't tell us whether the person has ever seen a patient, seen a patient in the wilderness, spent much time in the wilderness or whether they have ever had to make a real decision in the field.

In my upper echelon of molar grinders are statements of absolutes. These often reveal inexperience, not expertise, and as William Osler MD said "are made at the expense of a clean conscience." There isn't an “accepted” splint. There are splints that are crafted based on available resources and splinting principles. There is no single evacuation plan. There is only what we create based on sound plans, sound assessments and sound judgments. There are many lists of classic signs and symptoms, there is rarely a classic patient.

Last, but not least, is the phrase "our curriculum is evidence-based." This is an intriguing statement since quality evidence in first aid is rare, and in wilderness first aid it is almost non-existent. I prefer to say "evidence-informed." It acknowledges that our choices are a blend of science, experience and opinion.

Am I a curmudgeon? Probably. Am I innocent of these sins? Probably not. But I am aware. I'm trying to be virtuous and I do have the good fortune of being surrounded by colleagues who enjoy calling me to task when I slip.

Take care

Tod Schimelpfenig

Curriculum Director

NOLS Wilderness Medicine Institute

May 2012

Ibuprofen and Altitude Illness

Tod Schimelpfenig — Mon, 26 Mar 2012 16:42:00 GMT

I've been receiving emails about the recent online publication of a study in the Annals of Emergency Medicine titled “Ibuprofen Prevents Altitude Illness: A Randomized Controlled Trial for Prevention of Altitude Illness With Nonsteroidal Anti-inflammatories.” the study was highlighted by several of the health blogs and newspapers.

Eighty-six study participants took either ibuprofen 600 mg or placebo three times a day, beginning 6 hours prior to ascent from 4,100 feet (1,240 meters) to 12, 570 feet (3,810 m) in the White Mountains of California. The study looked at the incidence and severity of acute mountain sickness (AMS) as measured by the Lake Louise Questionnaire AMS score.

The ideal way to prevent AMS is to ascend slowly and acclimatize. Some folks don't want to do this, others may not be able to do it, and some folks still need assistance from medications. The standard has been acetazolamide (Diamox) which is well studied and received an endorsement in the recent WMS Consensus Guidelines for Prevention and Treatment of Altitude Illness.

Acetazolamide (Diamox) works by stimulating breathing, which facilitates acclimatization. We don't know how ibuprofen, an anti-inflammatory medication, works in AMS treatment. It might dampen an inflammatory component to AMS. This remains an active area of research.

In the recent study 69% of the people taking placebo and 43% of the ibuprofen group developed AMS. The severity of the AMS score was less in the ibuprofen group, but it did not meet the predetermined level of significance the authors hoped for.

Ibuprofen is appealing because it is non-prescription and readily available. Both medications have their side effects - pick your poison. This study suggest ibuprofen might work faster than acetazolamide, which should be started the day prior to ascent.

I don't think this study knocks acetazolamide (Diamox) from the altitude medication podium. I'm always skeptical of the latest and greatest drug for altitude illness. They come and they go. We need to see this work replicated, controlled for ascent profile, dehydration and other causes of headache and compared head-to-head with acetazolamide.

In the meantime , given no contraindications or adverse side effects,it is reasonable to use Ibuprofen as a non-prescription medication for prevention of AMS symptoms. If you have a history of AMS talk with your doctor about your choice of medication. Acetazolamide, with it's proven effect on acclimatization, and it's ability to smooth out erratic breathing during sleep,might be a better choice for you.

Risk-taking Behavior and Helmet Use in Skiers

Paul Auerbach — Tue, 28 Feb 2012 02:48:03 GMT

by Paul Auerbach, M.D.

The general consensus in the medical community regarding helmet use and skiing (also snowboarding) is that helmets should be worn to prevent or lessen head injuries related to falls and collisions. While a helmet may not significantly lessen deceleration forces upon the brain incurred by a sudden stop at high speed, they almost certainly somewhat soften the blow and are useful to prevent skull fractures. As they become standard equipment for recreational skiing, we will learn more about the psychology associated with their use.

“Risk-taking Behavior in Skiing Among Helmet Wearers and Nonwearers” is an original research article by Lana Ruži?, MD, PhD and Anton Tudor, MD, PhD in a recent issue of Wilderness & Environmental Medicine (22, 291-296, 2011). The objective of the study was to examine differences in on-the-snow ski behavior between helmet wearers and non-wearers. Using a survey taken of 710 skiers, the predictive power for risk-taking behavior was tested for gender, age, educational level, level of skiing, years of skiing, and helmet usage. Independent predictors for overall risk could be correlated with younger age (less than 35 years of age), male gender, higher skiing level, and helmet usage. Significantly higher risk was assessed for male helmet wearers, while this was not seen to be significant for female helmet wearers. The group found to be most prone to risk-taking behavior was the male occasional helmet wearers

It has been shown previously that male skiers generally take more risks than do female skiers. It is new information that wearing a helmet appears to increase risk-taking behavior, perhaps even further, in young males. What should we make of this? Perhaps wearing a helmet contributes to a feeling of invincibility, or creates an impression in the user that regardless of behavior, a helmet will be protective. Skiers and snowboarders should be made to understand that the benefits of wearing a helmet might possibly be neutralized by risky behavior. Risk profiles for high-speed impacts decline with age, but that should not obviate the need for a helmet. The elder brain is less tolerant of injury, and there is a higher likelihood that a significant blow to the head will result in bleeding within the skull.

Perhaps the largest elephant in the room is the notion I have heard offered by some that if one is not wearing a helmet, he or she is more likely to ski with caution, in order to avoid a collision or fall. This sounds good, but has never been proven. Furthermore, despite all best intentions, collisions occur because skiers catch an edge, are impacted by a colliding skier, slip on ice, or due to a myriad other reasons to precipitously strike the ground or a foreign object with their heads. The takeaway here is that a helmet is not a license to throw away caution, but it appears that this may be the interpretation by young, male skiers. We need to inform them otherwise.

Reposted with permission from the Medicine for the Outdoors Blog

Lightning Safety Awareness

Paul Auerbach — Wed, 25 Jan 2012 16:42:00 GMT

by Paul Auerbach

This post relates information learned in a recent issue (Volume 22, Number 3, 2011) of the journal Wilderness & Environmental Medicine, published by the Wilderness Medical Society.

In an article entitled “Lightning Safety Awareness of Visitors in Three California National Parks” by Lori Weichenthal et al, the authors set out to assess the level of lightning safety awareness among visitors at three national parks in the Sierra Nevada Mountains of California.

Having recently enjoyed a wonderful trip to Yosemite National Park (one of the study sites) and gotten caught in a powerful thunderstorm replete with multiple lightning strikes and wind-driven sheets of rain and icy hail, this is timely for me and very important for anyone who spends time outdoors.

There were no surprises in the conclusions derived from this study, but the investigation reinforces the notion that we don’t recall all that we need to know, or may have never fully understood lightning safety in the first place.

For instance, while participants in the national parks knew that lightning is more likely to strike in the afternoon, they were not aware of the dangers of seeking shelter in a small cave or group huddling. Few people understood proper body position, and other than avoiding metal objects or isolated tall trees, the respondents had too many errors (in my opinion) with respect to advice such as avoiding water or thick groves of trees. The authors appropriately concluded that there exist many educational opportunities, which can take many forms, including trailhead awareness placards, park visitor pamphlets, public service announcements, and national park web site education portals.

Here is some information on lightning avoidance from the 5^th edition of the book Medicine for the Outdoors:

1. Know the weather patterns for your area. Don’t travel in times of high thunderstorm risk. Avoid being outdoors during a thunderstorm. Carry a radio to monitor weather reports. Lightning can lash out from many miles in front of a storm cloud, in seemingly clear weather. If you calculate (see above) that a nearby lightning strike is within 3 miles (5 km) of your location, anticipate that the next strike will be in your immediate area. The “30-30 rule” specifies that if you see lightning and count less than 30 seconds before hearing thunder, seek shelter immediately. Since thunder is rarely heard from more than 10 miles away, if you hear thunder, it is best to curtail activities and seek shelter from lightning. Do not resume activities outdoors for at least 30 minutes after the lightning is seen and the last thunder heard.

2. If a storm enters your area, immediately seek shelter. Enter a hard-roofed auto or large building, if possible. Tents and convertible autos offer essentially no protection from lightning. Tent poles are lightning rods. Metal sheds are dangerous because of the risk of side splashes. Indoors, stay away from windows, open doors, fireplaces, and large metal fixtures. Inside a building, avoid plumbing fixtures, telephones, and other appliances attached by metal to the outside of the building.

3. Do not carry a lightning rod, such as a fishing pole or golf club. Avoid tall objects, such as ski lifts and power lines. Avoid being near boat masts or flagpoles. Do not seek refuge near power lines or tall metal structures. If you are in a boat, try to get out of the water. If you are swimming in the water, get out. Do not stand near a metal boat. Insulate yourself from ground current by crouching on a sleeping pad, backpack, or coiled rope.

4. Move off ridges and summits. Thunderstorms tend to occur in the afternoon, so attempt to summit early and be heading back down by noon. In the woods, avoid the tallest trees (stay at a distance from the tree that’s at least equal to the tree’s height) or hilltops. Shelter yourself in a stand of smaller trees. Avoid clearings—you become the tallest tree. Don’t stay at or near the top of a peak or ridge. Avoid cave entrances. In the open, crouch down or roll into a ball.

5. Stay in your car. If it is a convertible, huddle on the ground at least 50 yards (46 m) from the vehicle.

6. If you are part of a group of people, spread the group out so that everyone isn’t struck by a single discharge.

7. If your hair stands on end, you hear high-pitched or crackling noises, or see a blue halo (St. Elmo’s fire) around objects, there is electrical activity near you that precedes a lightning strike. If you can’t get away from the area immediately, crouch down on the balls of your feet and keep your head down. Don’t touch the ground with your hands.

More Lightning Safety Resources on OutdoorEd.com

Lightning Resources

Wilderness Medicine - 6th Edition released

Rick Curtis — Mon, 09 Jan 2012 02:25:00 GMT

I want to let everyone know about the release of the 6th Edition of Wilderness Medicine, the premiere textbook on the subject, edited by our frequent contributor Dr. Paul Auerbach. There are not too many books out there that I personally consider as "classics" in our field (titles like Mountaineering: The Freedom of the Hills comes to mind), for wilderness medicine, this book is a classic. I've used previous editions of this book for teaching first aid and it was one of my core reference books when writing the first aid chapter in The Backpacker's Field Manual. I'm really excited to see this new edition and that there will be an ebook version. At over 2,300 pages it's no wonder that this textbook is widely referred to as "The Bible of Wilderness Medicine."

This is one book that I recommend that every serious outdoor program have on the shelf as the ultimate reference guide. It covers every conceivable aspect of wilderness medicine in articles written by experts from around the world. What makes this book stand out is the combination of the breadth of coverage and its great readability. I try and keep current on wilderness medicine issues, but as a non-physician, reading things like the New England Journal of Medicine often leaves me scratching my head at the super-technical things that I don't have the background for. This textbook, written for both medical professionals and non-medical provides a great balance. Don't let the price tag deter you, any textbook of this magnitude is worth every penny. The book is available from the publisher Elsevier.com as well as on Amazon.com in hardcover and Kindle format and at Barnes and Noble in hardcover and Nook format.

From the Publisher:

"Quickly and decisively manage any medical emergency you encounter in the great outdoors with Wilderness Medicine! World-renowned authority and author, Dr. Paul Auerbach, and a team of experts offer proven, practical, visual guidance for effectively diagnosing and treating the full range of emergencies and health problems encountered in situations where time and resources are scarce. Every day, more and more people are venturing into the wilderness and extreme environments, or are victims of horrific natural disasters...and many are unprepared for the dangers and aftermath that come with these episodes. Whether these victims are stranded on mountaintops, lost in the desert, injured on a remote bike path, or ill far out at sea, this indispensable resource--now with online access at www.expertconsult.com for greater accessibility and portability-- equips rescuers and health care professionals to effectively address and prevent injury and illness in the wilderness!

From Paul Auerbach:

I’m thrilled to let you know that the 6th edition of the textbook Wilderness Medicine, for which I serve as Editor, is now available. The book is the culmination of more than three years’ work, and the publisher (Elsevier) has done a terrific job with the layout. The book contains 114 chapters, including a tremendous amount of information new to this edition.

This is the big reference book for medical and rescue professionals, educators, scientists, explorers, and others with wilderness medicine interests and activities. The depth of topic coverage underlies much of my other writing. The contributors have gone the extra mile to update their previous work, make new contributions, and do their best to create a comprehensive, encyclopedic work. I’m grateful to have had the opportunity to mold this edition, and am particularly pleased that the publisher allowed me to add chapters on matters related to wilderness preservation. I hope you find it an informative, useful, and fascinating book.

Here’s the Table of Contents:

PART 1 - Mountain Medicine

High-Altitude Medicine and Physiology
Avalanches
Lightning Injuries

PART 2 - Cold and Heat

Thermoregulation
Accidental Hypothermia
Immersion Into Cold Water
Nonfreezing Cold-Induced Injuries
Frostbite
Polar Medicine
Pathophysiology of Heat-Related Illnesses
Clinical Management of Heat-Related Illnesses

PART 3 - Burns, Fire, and Radiation

Wildland Fires: Dangers and Survival
Emergency Care of the Burned Victim
Exposure to Radiation From the Sun
Volcanic Eruptions, Hazards, and Mitigation

PART 4 - Injuries and Medical Interventions

Injury Prevention: Decision Making, Safety, and Accident Avoidance
Principles of Pain Management
Taping and Bandaging
Splints and Slings
Emergency Airway Management
Wilderness Trauma and Surgical Emergencies
Wound Management
Improvised Medicine in the Wilderness
Hunting and Fishing Injuries
Tactical Medicine
Combat and Casualty Care
Wilderness Orthopedics
The Eye in the Wilderness
Foot Problems and Care
Wilderness Dentistry
Management of Facial Injuries
Wilderness Cardiology
Wilderness Neurology
Chronic Diseases and Wilderness Activities
Mental Health in the Wilderness

PART 5 - Rescue and Survival

Wilderness Emergency Medical Services and Response Systems
Search and Rescue
Technical Rescue, Self-Rescue, and Evacuation
Litters and Carries
Helicopter Rescue and Aeromedical Transport
Essentials of Wilderness Survival
Principles of Meteorology and Weather Prediction
Jungle Travel and Survival
Desert Travel and Survival
Whitewater Medicine and Rescue
Caving and Cave Rescue

PART 6 - Animals, Insects, and Zoonoses

Protection from Blood-Feeding Arthropods
Mosquitoes and Mosquito-Borne Diseases
Malaria
Arthropod Envenomation and Parasitism
Tick-Borne Diseases
Spider Bites
Scorpion Envenomation
Bites by Venomous Reptiles in Canada, the United States, and Mexico
Envenoming and Injuries by Venomous and Nonvenomous Reptiles Worldwide
Bites and Injuries Inflicted by Wild and Domestic Animals
Bear Behavior and Attacks
Alligator and Crocodile Attacks
Wilderness-Acquired Zoonoses
Rabies
Emergency Veterinary Medicine

PART 7 - Plants

Seasonal and Acute Allergic Reactions
Plant-Induced Dermatitis
Toxic Plant Ingestions
Toxic Mushroom Ingestions
Ethnobotany: Plant-Derived Medical Therapy

PART 8 - Food and Water

Field Water Disinfection
Infectious Diarrhea From Wilderness and Foreign Travel
Nutrition, Malnutrition, and Starvation
Dehydration, Rehydration, and Hyperhydration
Living Off the Land
Seafood Toxidromes
Seafood Allergies

PART 9 - Marine Medicine

A Brief Introduction to Oceanography
Submersion Injuries and Drowning
Emergency Oxygen Administration
Diving Medicine
Hyperbaric Medicine
Injuries From Nonvenomous Aquatic Animals
Envenomation by Aquatic Invertebrates
Envenomation by Aquatic Vertebrates
Aquatic Skin Disorders
Safety and Survival at Sea

PART 10 - Travel, Environmental Hazards, and Disasters

Travel Medicine
Non-North American Travel and Exotic Diseases
Natural Disaster Management
Expedition Medicine
Global Humanitarian Medicine and Disaster Relief
Natural and Human-Made Hazards: Disaster Risk Management Issues

PART 11 - Equipment and Special Knowledge

Global Crimes, Incarceration, and Quarantine
Wilderness Preparation, Equipment, and Medical Supplies
Ultrasound and Telemedicine in the Wilderness
Outdoor Clothing for the Wilderness Professional
Nonmedical Backcountry Equipment for Wilderness Professionals
Ropes and Knot Tying
Wilderness Navigation Techniques and Communication Methods

PART 12 - Special Populations and Considerations

Training for Wilderness Adventure
Exercise, Conditioning, and Performance Training
Children in the Wilderness
Women in the Wilderness
Elders in the Wilderness
Persons With Special Needs and Disabilities
Wilderness and Endurance Events
Ranch and Rodeo Medicine
Wilderness Medicine Education
Medical Liability and Wilderness Emergencies
The Ethics of Wilderness Medicine
Native American Healing

PART 13 - The Wilderness

The Changing Environment
Biodiversity and Human Health
Health Implications of Environmental Change
Wilderness Management and Preservation
Leave No Trace
Space Medicine: The New Frontier
Appendix - Drug Stability in the Wilderness

INDEX

The hard copy book and e-reader versions both come with access to Elsevier’s expertconsult.com

Epinephrine for Out-of-Hospital Treatment of Anaphylaxis

Paul Auerbach — Sun, 18 Dec 2011 17:11:00 GMT

by Paul Auerbach, M.D.

For management of a serious (even life-threatening) allergic reaction, I have been teaching adults to administer epinephrine (adrenaline) by injection for years. This can be a lifesaving intervention. The Emergency Medical Services (EMS) community now concurs that EMS personnel should be trained to recognize a serious allergic reaction and be allowed to administer epinephrine. In a recent issue of the journal Prehospital Emergency Care (2011;15:570-576), there is an article by Jacobsen and Millin entitled "The Use of Epinephrine for Out-of-Hospital Treatment of Anaphylaxis: Resource Document for the National Association of EMS Physicians Position Statement" that details the use of epinephrine for this purpose.

The major new thrust of this document is to highlight the fact that the intramuscular (IM, directly into the muscle) injection route of administration is preferred, rather than the traditional primary recommendation to inject into the tissue space just under the skin layers ("subcutaneous"). This is because injection into the muscle tissue results in smoother and more reliable drug absorption, with higher peak therapeutic levels of the drug achieved sooner than with subcutaneous injection. The lateral thigh is often used for the IM injection; the outer upper arm is most commonly used for the subcutaneous injection. In an "autoinjector pen" used to administer epinephrine (often referred to by the brand name “EpiPen”), the needle may not be long enough to reach the muscle tissue of a large and/or obese person. However, if the epinephrine is injected into the subcutaneous tissue, it will in all likelihood still be effective, albeit perhaps not as quickly following the injection.

Here is advice about how to give epinephrine for a severe allergic reaction:

Administer aqueous epinephrine (adrenaline) 1:1,000 in an intramuscular or subcutaneous injection (depending on the depth obtained by the needle). The adult dose is 0.3 to 0.5 mL; the pediatric dose is 0.01 mL/kg of body weight, not to exceed a total dose of 0.3 mL. For weight estimation, 1 kg equals 2.2 lb. The drug is available in preloaded syringes in certain allergy kits, which include the EpiPen autoinjector and EpiPen Jr. autoinjector, the Twinject autoinjector (0.3 mg or 0.15 mg doses; 2 doses per unit), and the Ana-Kit. Instructions for use accompany the kits. The EpiPen and Twinject epinephrine products are generally easier for laypeople to use, because they require less dexterity to accomplish injection with them. The Twinject autoinjector and Ana-Kit syringe are configured with enough epinephrine for a second (repeat) dose, which is sometimes necessary. The Twinject is a true autoinjector for the first dose; the second dose is delivered as a routine injection from a concealed syringe and needle.

For dosing purposes, the EpiPen and Twinject 0.3 mg autoinjector should be used for adults and children over 66 lb (30 kg) in weight. Children 66 lb and under should be injected with the EpiPen Jr. or Twinject 0.15 mg autoinjector.

Take particular care to handle preloaded syringes properly, to avoid inadvertent injection into a finger or toe. Do not intentionally inject epinephrine into the buttocks or a vein. Epinephrine should not be exposed to heat or sun, but does not need to be kept refrigerated. If clear (liquid) epinephrine turns brown, it should be discarded. When administering an injection, never share needles between people.

Reposted with permission from the Medicine for the Outdoors Blog

Ski Helmets and Reaction Time

Paul Auerbach — Sun, 11 Dec 2011 17:08:00 GMT

by Paul Auerbach, M.D.

Ski season is upon us. Many experts (including myself) are of the opinion that helmets should be worn by all downhill skiers and snowboarders to help prevent head injuries. One of the “con” arguments proposed by some persons who object to wearing helmets is that they interfere with skiing in such a way as to perhaps make it more dangerous. In their opinion, this might occur by obscuring peripheral vision or diminishing the perception of sound. A very important article entitled article entitled “Do Ski Helmets Affect Reaction Time to Peripheral Stimuli?” (Wilderness & Environmental Medicine:22,148-150,2011) has recently been published by Gerhard Ruedl and colleagues from the Department of Sports Science at the University of Innsbruck in Austria.

The investigators sought to determine whether or not ski helmet use affects reaction time to peripheral stimuli. They used the Compensatory-Tracking-Test (CTT) in a laboratory situation to study 10 men and 10 women during four conditions in a randomized order: wearing a ski cap, wearing a ski helmet, wearing a ski cap and goggles, and wearing a ski helmet and goggles.

The CTT is performed by using a video projector that projects on a screen. The subjects being studied are seated at a table and instructed to respond to visual stimuli that appear on the screen, notably including the periphery of vision. The results were interesting. The lowest (quickest) mean reaction time (approximately 477 milliseconds) was noted for persons wearing only a ski cap. This was not statistically significantly different from the mean reaction time noted for persons wearing a ski helmet (approximately 478 milliseconds). The persons wearing both the goggles and cap or helmet had longer mean reaction times (514 milliseconds and 498 milliseconds, respectively). Note that all of these times are around one-half second.

What are the take-aways from this study? First, it is important to note that this is a simulation that involved only one measure—peripheral vision. It did not take into account the influence of sound. It was not a field experiment, so the influences of extraneous factors were not included. Such factors might be sounds (e.g., ski and wind noise, talking, etc.), thickness of helmet or design of goggles, ambient weather (e.g., sunshine or cloud cover), speed of travel on skis and snowboard, and so forth. However, it somewhat counters the notion that wearing a helmet per se diminishes reaction time to external visual stimuli, regardless of the situation. Furthermore, in a very controlled setting, the differences in reaction time are very, very small—approximately 30 milliseconds (30/1000 of a second), which would not seem to be a huge factor in causing ski accidents. So, while more studies need to be somehow accomplished in more realistic field settings, this is a good start to dispelling the automatic notion that wearing protective helmets is harmful to skiers wishing to avoid the sorts of accidents that cause head injuries.

Reposted with permission from the Medicine for the Outdoors Blog

Wilderness Medical Society Practice Guidelines for Frostbite

Paul Auerbach — Sun, 04 Dec 2011 17:08:00 GMT

by Paul Auerbach, M.D.

Led by Scott McIntosh, MD and his colleagues, the Wilderness Medical Society has published "Practice Guidelines for the Prevention and Treatment of Frostbite" (Wild Environ Med 2011:22;156-166). These guidelines are intended to provide clinicians about best evidence-based practices, and were derived from the deliberations of an expert panel, of which I was a member. The guidelines present the main prophylactic and therapeutic modalities for frostbite and provide recommendations for their roles in patient management. The guidelines also provide suggested approaches to prevention and management of each disorder that incorporate the recommendations.

In outline format, here is what can be found in these guidelines:

Introduction
Methods
Pathophysiology of Frostbite
Classification of Frostbite
Prevention
Field Treatment and Secondary Prevention
- Scenario 1: The Frozen Part Has the Potential of Re-freezing and Will Not Be Actively Thawed
- Scenario 2: The Frozen Part Can Be Kept Thawed and Warm With Minimal Risk of Refreezing Until Evacuation is Completed
Immediate Medical Therapy – Hospital (or High Level Field Clinic)
Other Post-Thaw Medical Therapy
Conclusions
Disclosure
References

The science and medicine of frostbite and other cold-induced injuries are not without discussion, opinions, and some controversy. These Practice Guidelines are an excellent beginning point for persons interested in the topic.

Read it Online

Read the Journal Article online at Wilderness & Environmental Medicine Journal.

Reposted with permission from the Medicine for the Outdoors Blog

Stinging Nettles

Paul Auerbach — Mon, 21 Nov 2011 05:18:47 GMT

by Paul Auerbach, M.D.

Hikers often brush up against injurious plants, such as poison oak or thorny shrubs. One particularly vexing plant is the “ubiquitous weed, Urtica dioica,” commonly known as stinging nettles. As described in an article entitled “Mechanism of Action of Stinging Nettles” (Wilderness & Environmental Medicine:22,136-139,2011) by Alexander Cummings and Michael Olsen, direct contact exposure to the weed causes immediate stinging and burning sensation on the skin. The authors exposed mouse skin to the plants and looked at this skin using an electron microscope. They found smooth nettle spicules that had pierced the skin surface, a few of which retained their bases, which appeared empty of liquid contents. The authors concluded that the mechanism of action of stinging nettles skin reaction was both biochemical and mechanical, likely caused by impalement of spicules into the skin.

Spicules of a stinging nettle, photo courtesy of Randy A. Nonenmacher (CC BY 3.0)The spicules are present as small “hairs” that are found on the stem and undersides of the leaves of the plant. Even light touch against the plant can cause a reaction, which is often characterized as instantaneous burning, itching, and sometimes a slight swelling of the skin. The nettles have been found to contain biologically active chemicals, which might account for part or all of the reaction. This current study shows that spicules, in whole or in part, are retained in the skin. To what extent the mechanical effect of spicule retention contributes to the reaction is yet to be determined, but it is certainly possible that there is such a mechanical effect.

It is not known if removing spicules soon after they enter the skin might be helpful, but it seems logical to make the attempt. There aren’t great ways to do this, because the spicules are so tiny and numerous. It is possible that a peeling method, in which the sticky side of adhesive tape is applied to the skin and then removed, might be helpful. It is certainly worth a try, if someone encounters stinging nettles and can rapidly get their hands on some tape (e.g., is carrying it with them).

Reposted with permission from the Medicine for the Outdoors Blog

Sawyer Squeeze Water Filtration System

Paul Auerbach — Mon, 31 Oct 2011 03:44:00 GMT

by Paul Auerbach, M.D.

As most of you know, I am sometimes sent outdoor health equipment and supplies to evaluate. I’ve recently received a few items worthy of mention.

Sawyer Squeeze Water Filtration SystemFirst, there is the Sawyer Products ‘Squeeze’ Water Filtration System. Advertised to be able to endure filtering 1 million gallons of water for the purpose of water disinfection/purification, this 0.1 micron filter is rated to be able to remove sediment, bacteria, protozoa, and cysts from water. It uses an in-line series of a bag (to contain the unfiltered water: 3 bags are supplied in sizes of one each at 32 ounces, 16 ounces, and 12 ounces) connected to a filter that simply screws onto a fitting at one end of the bag. The water is then squeezed through the hollow fiber-containing filter and exits the system through a discharge port similar to the pop-up closure top found on many water bottles, such as those used by cyclists.

It is easy to use, extremely lightweight, and convenient to pack and carry. The kit comes with a 60 milliliter syringe to be used to backwash (clean) the filter should it become less efficient, because it is becoming clogged with whatever has been removed from the water by the unit. You can learn more about this product and others from Sawyer Products at www.sawyer.com.

Reposted with permission from the Medicine for the Outdoors Blog

Comparing New Agents Used to Control Bleeding

Paul Auerbach — Sun, 16 Oct 2011 21:29:00 GMT

by Paul Auerbach, M.D.

Once of the major recent advances in trauma care has been the evolution of topical substances that can be applied to wounds in order to limit or stop hemorrhage (bleeding). This is very important in wilderness medicine, because uncontrolled bleeding is a leading cause of death from injuries. When the bleeding site can be approached in such a manner as to stop the bleeding, then something very valuable may possibly be done for the patient.

In article entitled “Comparison of Celox-A, ChitoFlex, WoundStat, and Combat Gauze Hemostatic Agents Versus Standard Gauze Dressing in Control of Hemorrhage in a Swine Model of Penetrating Trauma,” Lanny Littlejohn, MD and colleagues used an animal model of a complex groin injury with a small penetrating wound, followed by completely cutting the femoral artery and vein, to determine whether there was any benefit to one or another hemostatic (stops bleeding) agent in comparison to each other and to standard gauze dressing. To cut to the chase (no pun intended), the results showed that no difference was found among the agents with respect to initial cessation of bleeding, rebleeding, and survival. In this study, WoundStat was inferior with respect to initial cessation of bleeding and survival when compared to Celox-A.

The authors point out how important it is to control severe bleeding early in the course of a patient’s therapy, because at a certain point, bleeding leads to organ failure and a vicious cycle of severe acid-base imbalances, more bleeding, and the complications that might occur from blood transfusions. The different hemostatic agents, be they free granules poured into a wound or gauze impregnated with active substances, need to be readily available, easy to deploy, effective in a short period of time, not painful, and without complications. There are more than a few agents that fit the bill, so it’s important to be objective about the pros and cons of each agent. In this study, it was confirmed that they all work roughly equally effectively, so the choice often comes down to comfort of the user with a particular product and personal preferences.

What was surprising as an outcome in the study was the observation that a standard (nonmedicated) gauze dressing was as effective as any of the hemostatic agents. That contradicts some of the current rhetoric that I have heard at medical meetings from experts on wound care, who are beginning to swear by the use of hemostatic agents. If it is true that there are circumstances in which hemostatic agents do not add any benefit to the clinical process of stopping or limiting bleeding, we need to know, so that we don’t waste precious time and money deploying these agents. Obviously, if these agents are beneficial, we need to know about that as well.

A practical observation of this particular study was that a rolled, impregnated (with hemostatic agent) gauze introduced into a bleeding wound should first be unrolled prior to application, to avoid creating a congealed mass of gauze and blood that cannot be properly manipulated and positioned within the confines of the wound.

Reposted with permission from the Medicine for the Outdoors Blog

The Concept of Risk

Paul Auerbach — Tue, 11 Oct 2011 04:15:00 GMT

by Paul Auerbach, M.D.

Dr. Robert “Brownie” Schoene, an enormously talented, accomplished, and insightful physician who resides within the bedrock of wilderness medicine, gave a wonderful presentation about the concept of risk at the 2010 annual summer meeting of the Wilderness Medical Society. Risk is inherent in outdoor activities, whether it is part of exploration, adventure, science, or industry. I am going to summarize his approach to the topic, which is among the most important general concepts in the field, and editorialize with some of my thoughts.

When one thinks of risk related to outdoor health, it is about the possibility of suffering harm, damage, or loss. When a person is aware of the possibility of a specific risk, he or she usually weighs the risk against the possible benefits. When you hike on a slippery, snowy trail in early spring, where the trail winds over patches of ice near ledges from which a fall would cause a severe injury, is the experience worth the risk? When you ride a wave on your surfboard when the waves are intimidating and you are outside your comfort zone, is the improvement in performance worth the possibility of a tumble and possible muscle tear or broken bone? Sometimes the answer is easy. When I travel to a third world country, I always run the risk of acquiring infectious diarrhea. The benefits of the mission supersede the discomfort, and I both anticipate the risk and prepare for treatment by carrying oral rehydration supplies and appropriate antibiotics.

I love the quote from Winston Churchill that Dr. Schoene used to illustrate a risk-taker’s approach: “Risk more than you can afford to lose and learn the game!” Amen. Learn the game. Foolish risk occurs when a person expects to stay out of harm’s way, but doesn’t bother to learn, observe, prepare, anticipate, or react.

A risk seeker (sometimes foolishly) puts him- or herself in danger. A risk taker accepts the risks and proceeds into the activity, having weighed the benefits versus the risks, and a risk avoider (risk aversion) takes few or no risks, up to the point of being immobile via indecision. Because nothing in life is completely predictable, there is always a degree of uncertainty, and this factors into decisions. To the best extent possible, it makes sense to try to determine the degree of certainty, but that may oppose spontaneity, which is a component of the “spice of life.”

A major feature of any discussion about risk needs to be personal risk versus the risk of something happening to others, particularly companions, family, and friends, or any other category of individuals (or entities) for which one holds responsibility. In many circumstances, it’s acceptable to take personal risk. In a non-critical situation, placing others at risk is generally frowned upon. What if you are a coach or a guide? What is your feeling about head injuries in football? Do you feel comfortable exposing youth to these events? You can’t play football without banging heads. What about falling off a horse on the trail? Anyone who rides a horse can fall off. What about guiding an inexperienced person on a technical climb? You get the picture.

One person has commented that acceptance of risk is tantamount to admitting to have the ability to be instantly decisive in the presence of uncertainty during a moment of crisis. Perhaps, perhaps not. When one accepts risk, does one automatically have the ability to accept failure? I am not sure. I have seen many risk takers be so inclined because they do not comprehend the notion of failure. I have also seen them not be particularly smart or remotely capable of handling the situations into which they plunge. This is because they are not prepared and not of a disposition to solve problems. Rather, they create problems. Clearly, there is a complex interaction of knowledge, appreciation of the environment, disposition, personality, bravery, bravado, caution, apprehension, and fear.

To mitigate risk, even if one wishes to accept it, it is important to act responsibly, prepare for both the expected and unexpected, accept the responsibilities of risk and therefore become a more engaged and reliable participant, and be a student of historical accounts of how people were afflicted and how they responded in similar situations.

In the Wake of Hurricane Irene – Methods of Water Disinfection

Paul Auerbach — Tue, 13 Sep 2011 02:06:39 GMT

by Paul Auerbach, M.D.

In the wake of Hurricane Irene, many people will be without electrical power for days. If they need to disinfect water to obtain drinking water, the following are some techniques that may be used:

Water disinfection is the treatment of water with chemicals, boiling, or filtration in order to remove agents of infectious disease, such as bacteria and cysts. The principal offending agents in contaminated water or on unwashed food that cause illness and diarrhea are the bacteria Salmonella, Shigella, E. coli, and Campylobacter, and the flagellate protozoan Giardia lamblia.

All containers should be wiped clean to remove external moisture and dirt. If the water to be disinfected is cloudy or dirty, it should be allowed to rest for several hours in order for large particles to settle to the bottom. The top portion can be poured off—if possible, it should be poured through a filter or fine cloth.

Coagulation and flocculation techniques can remove smaller suspended particles: Add a pinch of alum (an aluminum salt) to a gallon (3.8 liters) of water and mix well, then stir occasionally for 60 minutes. Allow the water to rest while the aggregated particles settle, then pour off the upper (and hopefully clearer) part through a paper filter (such as a laboratory-grade filter with a pore size of 20 to 30 microns).

Water may be disinfected by any of the following methods:

1. Boil the water.

At sea level, when water has been boiled for a few minutes, it can be considered to have been disinfected. Giardia cysts are instantly killed in water heated to 158° F (70° C). To play it safe, keep boiling it for a few minutes at this temperature to kill off all bacteria and most viruses. Hepatitis A virus requires a full minute of boiling to assure inactivation. To provide a wide margin of safety, boil the water for three minutes.

Time and temperature have an inverse relationship with respect to water disinfection: The higher the temperature, the less time is required, and vice versa. For instance, pasteurization of food products can occur at a lower temperature (158° F, or 70° C) if 30 minutes at this temperature are allowed. Sterilization (killing of all microorganisms) occurs after five to 10 minutes of boiling at sea level.

2. Use a halogen, such as iodine or chlorine, as a chemical disinfectant.

The rate at which halogens kill microorganisms depends upon the concentration (measured in mg per liter, or parts per million [ppm], which are equivalent) of halogen and time allowed for disinfection. At a given water temperature and pH, contact time is inversely related to concentration. Thus, you double the contact time if half the concentration of halogen is present. Decreased (cold) water temperature or cloudy (more organic material) water requires a longer contact time or higher halogen concentration. Halogens can create an unpleasant taste if the concentration exceeds four mg/liter. They can lose effectiveness after prolonged exposure to moisture, heat, or air, and may be corrosive or stain clothing. In general, to improve taste, use a lower concentration of halogen for a longer contact time. Eight mg/liter (or ppm) is considered the concentration of iodine effective for water disinfection in room-temperature, clear water. A pregnant woman or a person with thyroid disease or iodine allergy should consult a physician before using any iodine compound for water disinfection.

Water disinfection tablets, such as Potable Aqua® (see below) and other iodine- and chlorine-based products may be used inside plastic hydration bladders, such as those found in the CamelBak®. While they may discolor the plastic, they do not degrade it.

Add one tablet of fresh tetraglycine hydroperiodide (Potable Aqua®, Globaline, Coughlan’s, EDWGT) to one quart (liter) of water and allow the water to stand for 15 minutes. If the water is cloudy, use two tablets. If the water is cold, allow one hour after adding the tablets before drinking. Each tablet releases approximately 8 mg/liter of iodine. Do not leave an open bottle exposed to high heat and/or humidity. Potable Aqua Plus includes oxidizing tablets to remove the iodine taste after disinfection.

Add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	1 tab for 15 minutes	2 tabs for 30 minutes
cold	1 tab for 60 minutes	2 tabs for 60 minutes

After adequate time for disinfection has elapsed, add a few grains of sodium thiosulfate per quart (liter) of water; this kills the iodine taste. Ascorbic acid (vitamin C) is also effective. Any fruit flavorings that contain vitamin C should be mixed in after full time for disinfection has elapsed. Granular activated charcoal removes organic material, chemicals, and radioactive particles by adsorption, but does not remove all microorganisms, and thus cannot be relied upon to disinfect water. Rather, it should be used to improve taste and clarity. Use it after water has been properly disinfected.

Zinc metal reduces free chlorine or iodine in solution through a chemical reaction. A wand of zinc bristles stirred into a quart (liter) of water for 4 minutes will remove 10 mg/liter of residual chlorine.

Because a 50-tablet bottle of tetraglycine hydroperiodide contains only 0.4 g of iodine (1/50 the lethal dose), the tablet method is very safe. If you use military surplus iodine tablets, they should be steel gray in color and not crumble when pinched by two fingers; discard older, crumbled tablets. Also, no matter what chemical disinfection system you use, allow disinfected water to seep around the cap and threads of your canteen or water bottle, in order to disinfect them.

Another method is to add 8 to 10 drops (0.5 ml in each drop) of standard 2 percent iodine tincture per quart (liter) of water and allow it to stand for 15 minutes. Use a dropper for measurement. If the water is not at least 68° F (20° C), this technique may not eliminate Giardia. If the water is cold, allow it to stand for 1 hour before drinking. If you have extra time and do not like the iodine taste, use four to five drops of iodine and allow the water to stand for 8 hours or overnight. Five drops of tincture of iodine disperses to approximately 4 mg/liter.

add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	5 drops for 15 minutes	10 drops for 30 minutes
cold	5 drops for 60 minutes	10 drops for 60 minutes

Another iodine product that can be used to disinfect water, but has not definitively been proven effective for this purpose, is 10 percent povidone iodine (Betadine) solution (not “scrub”):

add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	8 drops for 15 minutes	16 drops for 30 minutes
cold	8 drops for 60 minutes	16 drops for 60 minutes

Another method is to fill a 1 oz (30 ml) glass bottle with iodine crystals (U.S. Pharmacopoeia [USP] grade, resublimed: 2 to 8 grams), then fill the bottle with water. The bottle should have a paper-lined Bakelite cap. Warm the water to 68 to 77° F (20 to 25° C). Shake vigorously, then allow the crystals to settle to the bottom for 1 hour. This will create a saturated solution of iodine. As a crude measure, pour at least half of this liquid (not the remaining crystals), or approximately 12.5 to 15 ml, through a fine filter (such as Teflon) into a quart (liter) of water and allow it to stand for 30 minutes. If the water temperature is not at least 68° F (20° C), this technique may not eliminate Giardia. The crystals may be reused up to 1,000 times. Two grams (0.07 oz) of iodine represents a potentially lethal dose if ingested, so it is absolutely essential to keep the iodine crystals out of the hands of children. A commercial iodine crystal system that can be reused to disinfect up to 2,000 quarts (liters) of drinking water is sold as Polar Pure Water Disinfectant.

If one capful from a 2 oz (59 ml) bottle equals approximately 2.5 ml, then using a saturated solution prepared from iodine crystals in water:

add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	5 capfuls for 15 minutes	10 capfuls for 30 minutes
cold	5 capfuls for 60 minutes	10 capfuls for 60 minutes

An alcohol-iodine solution can be prepared by adding 8 g of iodine crystals to 100 ml of 95 percent ethanol. The resulting supernatant yields 8 mg iodine per 0.1 ml. To add to water, measure with an eyedropper:

add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	0.1 ml for 15 minutes	0.2 ml for 30 minutes
cold	0.1 ml for 60 minutes	0.2 ml for 60 minutes

3. Filter the water through a category-three (as set for purification by the Environmental Protection Agency) water treatment device.

Manufacturers who sell representative devices are the Mountain Safety Research, Katadyn, AquaRain Filter Systems, General Ecology Inc., Recovery Engineering, Timberline, Stearns Outdoors Inc., McNett, and Sawyer Products. The Sawyer Point Zero Two™ water filter, with a 0.02 micron filter, is rated to remove viruses. This product is available with a bucket adapter kit, or can be fitted to four liter bags or a special water bottle.

If the filter doesn’t come with a “prefilter” (nylon mesh or screen) to remove large particles, pour the water through filter paper (like coffee filter paper) or fine cheesecloth. This helps keep your expensive water filter from clogging up, allows it to work more efficiently, and will improve the appearance and taste of the water.

4. Use halazone prodcuts to disinfect water.

Halazone (a mixture of monochloraminobenzoic and dichloraminobenzoic acids) or other chlorine (bleach) products have been considered less effective for field water disinfection. Halazone has been characterized as losing 75 percent of activity after two days’ continuous exposure to air with high heat and humidity; having a shelf life of six months; and decreasing potency by 50 percent after storage above 104° F (40° C). Therefore, you should obtain a new bottle every three to six months.

Each Halazone tablet releases 2.3 to 2.5 mg/liter of chlorine. To disinfect water:

add to 1 quart (liter) of water:

water

clear

cloudy

warm (>15° C, 59° F)

5 tablets for 15 minutes

2.5 tablets for 30 minutes

7 tablets for 15 minutes

5 tablets for 30 minutes

cold

5 tablets for 60 minutes

7 tablets for 60 minutes

Liquid bleach (hypochlorite solution; household bleach, usually 5.25 percent) can be used to disinfect water via chlorination. There should be a faint smell or taste of chlorine before drinking.

For 5.25 percent bleach, add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	2 drops (0.1 ml) for 30 minutes	4 drops (0.2 ml) for 30 minutes
cold	2 drops (0.1 ml) for 60 minutes	4 drops (0.2 ml) for 60 minutes

For 1 percent bleach, add to 1 quart (liter) of water:

water	clear	cloudy
warm (>15° C, 59° F)	10 drops (0.5 ml) for 30 minutes	20 drops (1 ml) for 30 minutes
cold	10 drops (0.5 ml) for 60 minutes	20 drops (1 ml) for 60 minutes

5. Superchlorination and dechlorination.

Superchlorination followed by dechlorination is an effective technique. This is a more complicated method that requires understanding and experience. Add 27 g or more of calcium hypochlorite crystals to a gallon (3.8 liters) of water to attain a chlorine concentration of 27 to 30 parts per million. After the requisite disinfection time (10 to 30 minutes), add six drops of concentrated (30 percent, caustic) hydrogen peroxide to dechlorinate the water. The chemical reaction produces calcium chloride (which remains in solution), water, and oxygen.

6. Aquamira® water treatment.

Aquamira® water treatment uses stabilized 2 percent chlorine dioxide combined with an activator (5 percent food grade phosphoric acid) to improve the taste of water. One kit can be used to treat more than 120 liters of water. Mix 7 drops of the two bottles together, and let sit 5 minutes, then pour the contents into 1 quart of water. Oxygen is released in a highly active form to kill odor-causing bacteria. The process takes approximately 20 minutes.

7. The SteriPEN™

The SteriPEN™ carries the promotional byline of “safe drinking water anywhere.” Distributed by Traveler’s Supply, Inc., this unique hand-held water purifier that uses ultraviolet light (UVL) is advertised to fit into most plastic consumer water bottles as well as other types of containers up to 32 ounces (1 liter). It operates on 4 AA batteries, with nickel-metal-hydride or lithium batteries recommended. According to the distributor, only 48 seconds of exposure to the UVL is required to disinfect 16 ounces (1/2 liter) of water and 90 seconds for 32 ounces (1 liter). The claim is that the device is effective against common outdoor and household pathogens, as well as less common micro-organisms, to include bacteria, viruses, and protozoa. The test results are found at an Internet link provided by the company. According to the product literature, the SteriPEN™ meets U.S. Environmental Protection Agency standards for microbiological water purifiers. A filter can be used to remove particulates from the water prior to UV treatment.

UVL works for water disinfection by destroying the DNA of microbes. This keeps the germs from reproducing, which is necessary in order for them to make a person ill. The light emitted by the SteriPEN™ device is in the UV-C range, of wavelength 254 nanometers. This wavelength is germicidal (kills germs) by causing adjacent thymine base nucleotides in DNA to bond together, which prevents them from being properly recognized (“read”) in the replication process, which is necessary for DNA to allow a micro-organism to reproduce. Thus, the germ(s) is rendered harmless. Used as directed, the UVL exposure is of no consequence, as this wavelength of UVL does not pass through most materials (e.g., glass, metal, ceramic, and nearly all plastics). Furthermore, the underside of the air/water surface in a water container acts as a reflector for UV-C. So, if the SteriPEN™ lamp is completely immersed in water and used according to the instructions, the UV-C is contained and does not pose any health risk to the user. For additional safety, the SteriPEN is equipped with water sensors and will not operate unless the lamp is under water. The SteriPEN™ contains a microcomputer that controls operation time, according to information it receives from integrated temperature sensors and user indication of the volume of water to be disinfected. During use, the device should be used to gently stir the water. It is intended for use in clear water, so cloudy water must be filtered or otherwise made clear prior to using the SteriPEN™. Disposable lithium or rechargeable AA nickel metal hydride batteries will provide many more disinfection cycles than will alkaline batteries. The latter are better in a cold weather situation.

The Role of the Routine Physical Examination in Young People

Paul Auerbach — Mon, 29 Aug 2011 11:20:00 GMT

by Paul Auerbach, M.D.

Increasing numbers of young people participate in outdoor activities, including strenuous competitive athletics. In so doing, they subject their bodies to stresses that are more intense and prolonged than those presented by a largely sedentary life. Every story of a sudden death in a young person is a tragedy, and usually accompanied by commentary pondering the role and utility of pre-activity screening. Could the death have been prevented? What was the physiological condition of the deceased? Could the collapse, often attributed to a heart problem, have been predicted? Was there an examination or evaluation that might have indicated that the deceased was at greater risk, or should have been held out of the activity? These are all important questions, with no simple answers.

Sudden collapse and cardiac arrest in a young person seems wrong. It shouldn’t happen. It is a parent’s worst nightmare. Similar horrors occur on the freeway when a teenage driver is killed, or at the beach when a surfer is tossed in a monster wave and drowned. We know a great deal about injury prevention; much of our teaching and experience points to errors in judgment. But the situation is different when the seemingly healthy slumps to the ground without a pulse. That person has been taken by surprise in a cruel act of fate.

Sometimes we learn that the victim had a congenital or acquired heart abnormality, such as idiopathic hypertrophic subaortic stenosis, a seizure disorder, or a propensity to abnormal heart rhythms. A young person may be walking around with an inflamed heart muscle after apparently recovering from a viral infection, and not know until it is too late that his or her heart is operating at a greatly reduced capacity, such that heart failure is just around the corner. The young person with a brain aneurysm is in great shape until the dilated blood vessel bursts and leaks a lethal torrent into the confined space within the skull.

A large proportion of sudden adverse health events—whether a first serious attack of ketoacidosis associated with diabetes, a stroke in a person with a brain aneurysm, or cardiac arrest in a person with a potentially lethal heart rhythm disorder—come without any antecedent event or other warning. To what degree should apparently healthy persons be screened for the possibility of an occult problem?

Warning Signs

To begin with, the child should receive a prompt physical examination if there is a chronic problem with any of the following:

fainting spells
frequent urination
fatigue out of proportion to the activity
weight loss
shortness of breath
palpitations (particularly with an irregular pulse)
chest pain

The doctor will screen for heart problems and other abnormalities. Routine parameters of good health, such as appropriate pulse rate, blood pressure, ease of breathing and breath sounds, and ideal body mass and total weight are essential. Similarly, routine laboratory testing, such as blood counts, urinalysis, blood glucose, and essential electrolytes establish what is hopefully a normal baseline for the participant.

What is “Extra”?

An electrocardiogram (ECG, EKG – “heart tracing”) is not usually part of a basic physical examination in youth. The test will detect arrhythmias and certain structural abnormalities of the heart. An echocardiogram bounces sound waves off the heart and determines anatomy and function. Combined with the ECG, an ultrasound becomes a very reasonable heart screening regimen for persons of all ages.

Exercise-associated events, such as dizziness, fainting or chest pain, should be examined with an ECG and echocardiogram, and perhaps a stress test (“treadmill”). Further testing is guided by the results of these three examinations.

What is the Value of “Family History?”

Certain congenital conditions and many medical disorders have a basis in genetics. Knowing whether or not your father or mother had heart problems is useful to help determine your risk, but in my opinion, a “negative” family history does not rule out the need for a physical examination and proper testing. The person who collapses with a heart attack may be the first one in the family to do so.

What Are the Controversies in Testing?

False Positive Results

There is always a possibility that the results of a test deemed positive for a problem are in fact incorrect—there is not a problem, so the test is “false positive.” If the false positive rate is high, then there will be too much unnecessary follow-up testing, and, furthermore, persons may be precluded from activities when they are perfectly normal.

Cost

How many lives are saved for what total dollar amount? How much is it worth to society to save a small number of athletes who, without screening, might go on to collapse and die? Finally, what is the quality of “mass screening?” Do we rush through the exams and make mistakes with the interpretations because we don’t have a high index of suspicion combined with a hasty effort?

Final Words

My recommendation, which is entirely based on opinion, is that a healthy child, who has received all the normal examinations and healthcare, should have a comprehensive physical examination prior to undertaking a new and very strenuous activity (be it on the playing field, underwater, or climbing a mountain). A baseline EKG is good for people to have in their possession for future medical reference, provided that it will be safely stored, and not misplaced or lost. If there is any suggestion of a heart problem by virtue of history or exam, or if there is a significant family history of heart abnormalities, an echocardiogram should be obtained.

reposted with permission from the Medicine for the Outdoors Blog

Fatal Bear Attack

Paul Auerbach — Mon, 22 Aug 2011 04:42:00 GMT

by Paul Auerbach, M.D.

By now, most everyone is familiar with the tragic circumstances in which a visitor on a trail in Yellowstone National Park on July 6, 2011 surprised a brown (grizzly) bear with cubs, provoking a fatal attack. Fortunately, events like this are rare. At the same time, they are also predictable by virtue of our understanding of bear behavior, particularly in the wildland-urban interface. It was not the victim’s fault, and our hearts go out to his family and friends. For the benefit of others who will backpack and explore in bear country here is an excerpt about avoidance of hazardous animals, in particular bears, adapted from the book Medicine for the Outdoors:

Avoidance of Hazardous Animals

Most wild animal encounters can be avoided with caution and a little common sense. Follow these rules:

1. Do not surprise or otherwise provoke animals. Unless they are apex predators, starving, senile, or ill, most animals will not attack humans without provocation. Do not corner or provoke a carnivore. Do not tease animals. Do not approach an animal when it is with young. If you are a photographer approaching a wild animal that may become provoked and charge, do not come any closer to the animal than 100 yards distance. Some experts say that you should attempt to stay even further away from bears.

2. Do not disturb a feeding animal. Do not explore into its feeding territory, approach during rut, or disrupt mating patterns.

3. Do not separate fighting animals using your bare hands. If possible, drive animals apart using a long stick or club.

4. In bear country, make your presence known by calling out, clapping your hands, or otherwise making noise, particularly when approaching streams and blind spots on the trail. If you are a jogger on a trail, you may approach a bear more rapidly than it has time to flee, so it is best to stay off trails frequented by bears if you are traveling at a brisk pace.

5. Hang all food off the ground in trees away from the campsite. Never keep food or captured game inside a tent. Use proper food storage to keep food away from bears. Cook at a site away from the sleeping area. Do not sleep in clothes worn while cooking or eating.

6. Make noise when hiking, particularly on narrow paths or through tall grass. Walk slowly. If you confront a brown (grizzly) bear, avoid eye contact and try to slowly back away. If you confront a black bear, shout, yell, throw rocks or sticks, or do whatever you can to frighten off the animal.

7. If attacked by a bear, do not try to outrun it; you can’t. If you are carrying pepper spray (at least one percent capsaicin or capsaicinoids) in a canister intended for use against a bear (“bear pepper spray” that meets EPA standards; a spray distance of 25 feet under optimum conditions, minimum spray duration of six seconds, minimum net content of 7.9 ounces or 2.25 grams), use it if you have time. Personal defensive spray, such as Mace, will likely not work because the canister shoots a relatively thin stream and the substance is not sufficiently potent. Carry the spray where it is obvious and can be immediately deployed. It should be on a holster on your waist or chest, not in the bottom of your pack. Show your companions its location.

8. If you are attacked by a bear and not carrying bear pepper spray, cover your head and the back of your neck with your arms and curl into a fetal position or lay flat on the ground, face down, to protect your abdomen. If you are wearing a backpack, keep it on for additional protection. Use your elbows to cover your face if a bear turns you over. After a bear attack, remain on the ground until you are certain that the bear has left the area. More than one victim has successfully protected himself during the initial attack, only to arise too soon (before the bear has lost interest and left the area) and be mauled during the second attack.

5. Never leave a small child alone with an animal, regardless of the animal’s demeanor.

6. Do not pet or feed animals.

reposted with permission from the Medicine for the Outdoors Blog