#242 Wilderness Medicine: Prepare for Disaster

November 16, 2020 | By Deb Gorth

Altitude Sickness, Frostbite, Animal Bites, Thermoregulation, and Wound Care with Dr. Tom Deloughery

Explore the essentials of Wilderness Medicine and prepare yourself for austere environments as we discuss Altitude Sickness, Frostbite, Animal Bites, Thermoregulation, Wound Care and the proper way to apply a tourniquet.

Thinking about outdoor escapes and vacations now more than ever? Listen as our esteemed guest Dr. Thomas DeLoughery @Bloodman (Oregon Health & Science University) takes us through the fascinating, and at times chilling, world of Wilderness Medicine. This episode will empower you to explore the great outdoors as safely as possible.  We discuss the breadth of wilderness medicine, multiple unique clinical entities encountered in austere environments, and practical ways to protect yourself and others on your adventures.  This episode is truly wild!

Listeners can claim Free CE credit through VCU Health at http://curbsiders.vcuhealth.org/ (CME goes live at 0900 ET on the episode’s release date).

Show Notes | Subscribe | Spotify | Swag! | Top Picks | Mailing List | thecurbsiders@gmail.com | CME!

Credits

• Written, Produced, and Infographic by: Avital O’Glasser MD, FACP, FHM
• Show Notes: Deborah Gorth ScM and Avital O’Glasser MD, FACP, FHM
• Cover Art: Kate Grant, MD
• Hosts: Matthew Watto MD, FACP; Paul Williams MD, FACP; Avital O’Glasser MD, FACP, FHM
• Editor: Matthew Watto MD, FACP (written materials); Clair Morgan of nodderly.com
• Guest: Thomas DeLoughery MD, MACP, FAWM

Sponsor

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VCU Health CE

The Curbsiders are partnering with VCU Health Continuing Education to offer FREE continuing education credits for physicians and other healthcare professionals. Visit curbsiders.vcuhealth.org and search for this episode to claim credit. See info sheet for further directions. Note: A free VCU Health CloudCME account is required in order to seek credit.

How to Claim VCU CME Credit

Time Stamps

• Sponsor – Provider Solutions and Development https://curbsiders.vcuhealth.org/
• Sponsor – VCU Health CE curbsiders.vcuhealth.org
• 00:00 Intro, disclaimer, guest bio
• 03:45 Guest one-liner, advice and Picks of the Week*
• 08:10 Sponsor – Provider Solutions and Development https://curbsiders.vcuhealth.org/
• 09:00 Case of mountaineering; What is Wilderness Medicine?

• 12:05 What’s in your first aid kit?

• 21:36 Altitude sickness: acute mountain sickness, high altitude cerebral edema and High altitude pulmonary edema

• 31:25 Hypothermia  
• 39:36 Frostbite 

• 47:25 Hyperthermia: Heat exhaustion and Heat stroke; How much water should you drink?

• 51:55 Bat bites and rabies

• 58:20 Snake bites

• 66:03 Wound care and tourniquets

• 75:40 Take Home Points; Outro; Bonus clip
• Sponsor – VCU Health CE curbsiders.vcuhealth.org

Wilderness Medicine Pearls

1. Wilderness medicine is practicing medicine in an austere environment. 
2. Clinicians from any specialty can get involved in wilderness medicine and pursue additional training.
3. Always bring an emergency kit on outdoor expeditions.  Specific contents beyond basic first aid supplies, such as pharmaceuticals, will vary based on the location and nature of the expedition..  
4. Many injuries and adverse events in the wilderness start with assuming “best case scenario” or taking shortcuts. Always prepare for the unexpected, including the need to spend the night in the wilderness.
5. High altitude sickness is a spectrum of illness that includes acute mountain sickness and that can progress to high altitude cerebral edema; High altitude pulmonary edema is a separate altitude-related clinical entity. AMS and HACE can be prevented by slow ascent or prophylaxis with acetazolamide 125mg BID.  Treatment includes acetazolamide 250mg BID or dexamethasone.
6. The Swiss Model of Hypothermia outlines the severity stages and clinical findings of hypothermia.  Patients with hypothermia need to be rewarmed but also moved very carefully, if at all, to avoid risk of cardiac arrest
7. Animal bites need to be treated seriously, with local health organizations vital in determining specific risk of transmissible illnesses such as rabies and post-exposure prophylaxis/treatment needs such as antivenom or antibiotics.
8. Long feared for the risk of limb loss, tourniquets now have a role in triage in the field and are an essential part of emergency kits.  Advances in local hemostasis such as bandages impregnated with procoagulants are additionally available.

Wilderness Medicine

What is wilderness medicine?

At its core, wilderness medicine is practicing medicine in an austere environment, including everywhere from space to disaster scenarios. While it has taken on this broad definition over the years, outdoor adventure is the mainstay of wilderness medicine. The Wilderness Medical Society offers fellowships, education, research support, and conferences. Travel medicine is a close sibling of wilderness medicine and has its own organization, the International Society of Travel Medicine.

The best way to get into wilderness is to go to a wilderness medicine meeting and/or sign up for a wilderness medicine course. And then, go for a hike.

What is in your first aid kit?

While there is no shortage of premade wilderness first aid kits, it is worth creating your own to suit your specific needs; a wilderness first aid kit should be tailored to the type of trip, climate of the locale, number of participants, and length of trip. Some of the basics are: analgesia (acetaminophen and NSAIDs), oral rehydration salts, anaphylaxis management (antihistamines and EpiPen®), bandages, gauze/absorbent pads, materials for sprinting (ace bandage), and medicine useful for high altitude (acetazolamide and dexamethasone). Antibiotics can be useful for longer trips, with amoxicillin-clavulanic acid (Augmentin), trimethoprim-sulfamethoxazole (Bactrim), or doxycycline being particularly well suited to treat infected scrapes or UTIs. 

Don’t forget to bring your home medications and remind your expedition partners to bring their own home medications.  Know how to keep medications, like insulin, safe with changes in temperature and altitude! For example, prevent insulin from freeezing and vent insulin bottles to prevent shattering as pressure changes! Separate guidance exists for hiking with chronic illnesses (Auerbach’s textbook chapter 92 “Older Adults in the Wilderness”).

When going into the wilderness, always prepare for the unexpected. The best wilderness medicine is not practicing wilderness medicine. A common mistake is assuming a best-case scenario and only preparing for such.  Be prepared to stay overnight unexpectedly.  Another mistake is being too strongly goal directed or cutting corners; too many injuries begin with trying to take a shortcut. Why treat a sunburn when you can wear sun protection? Always bring extra clothing, food, and water. Beware of overreliance on technologies; have the ability to navigate without cell phone reception.  Similarly….don’t bring a stethoscope.  However, is there a role for POCUS?

Dr. DeLoughery’s expert opinion: “space can be better used for bandaids”.

Altitude Sickness

Sudden altitude ascension (>2500m or 8200ft) without allowing for time to acclimatize can lead to altitude sickness.

Acute mountain sickness and high altitude cerebral edema

Acute mountain sickness (AMS) comprises a constellation of symptoms including headache, nausea, vomiting, and fatigue (Luks et al. 2019). High altitude cerebral edema (HACE) represents a severe form of acute mountain sickness. Risk stratification can be a useful tool to determine who needs altitude sickness prevention (Campbell et al, 2015). Individuals are low risk if they have no history of altitude sickness and gradually ascend to <2800 meters. Moderate risk individuals have a history of AMS and plan on ascending no higher than 2500-2800 m in 1 day. Having a history of AMS and ascending to >2800 m in 1 day is considered high risk. Additionally, ascending >3,500 m in 1 day regardless of AMS history is high risk. HACE affects younger individuals more, perhaps due to behavioral factors or larger baseline brain volume. Gradual ascent as well as sleeping at an altitude below maximum altitude reached during waking hours (“Climb high, sleep low”) are preventative measures. Dr. Hackett, a key researcher in altitude physiology, is also the coauthor on a high yield Up-to-Date article on the subject.

A survey of adults traveling to resort communities in the Rocky Mountains (6300–9700 feet elevation) found that 25% of these individuals developed acute mountain sickness with an odds ratio favoring acute mountain sickness of 3.5 for individuals whose permanent residence was below 3000 feet (Honigman et al 1993).  Acute mountain sickness happens at medical meetings, too (Montgomery et al 1989; Dean et al, 1990)!

Acetazolamide speeds acclimatization. 125mg BID helps prevent altitude sickness or HACE (Low et al 2012); continue for 2-3 days after reaching maximum altitude. Acetazolamide 250mg BID can be used for treatment (Luks et al. 2019).  However, it may reduce exercise performance. 

Dexamethasone can be used for AMS and HACE treatment (4-8 mg q6 hours) as well as prevention in high risk patients or situations (Luks et al. 2019).  

High altitude pulmonary edema

Although also caused by altitude, high altitude pulmonary edema (HAPE) is a separate clinical entity than acute mountain sickness/HACE.  HAPE has been reported even at altitudes as low as ski resorts. It carries individual susceptibility, and if you have it once, you would likely get it again. There is little consensus on genetic risk factors. Nifedipine can be used for prevention or treatment, working as a pulmonary vasodilator and accentuating hypoxic vasoconstriction (Luks et al. 2019).  Treatment can also include a portable hyperbaric bag (ex. The Gamow® bag), which is an inflatable pressure bag that a person can fit inside.  The bag can be pressurized to an effective altitude thousands of feet lower than current altitude within minutes. 

Hypothermia

Hypothermia can be insidious (Dow et al, 2019). Paradoxical reactions can occur as the brain gets cold but one perceives being warm. The adage “cotton kills” is important–cotton saturated by sweat can lose the ability to provide insulation. Shivering increases metabolism five times so the shivering response is important to the body trying to maintain temperature. Make sure your hypothermic patient is well fed so they can generate an adequate shivering response.

(The Swiss Model of Hypothermia, adapted from Durrer et al, 2003; Brown et al, 2012).  

Separate a person from the ground to avoid additional temperature loss (by conduction). If their clothing is wet and there isn’t dry clothing available, wrap them in additional insulation to prevent evaporative losses. 

Hypothermic patients need to be physically handled very carefully, as cardiac arrest can occur when warm core blood begins to circulate and rapidly cools. Keep them horizontal! Follow the Cold Card. 

Frostbite 

Frostbite is very common (McIntosh et al, 2019). Frostnip is a superficial injury. Frostbite is tissue damage. At first glance, frostbite does not look bad as it is often just pale hard skin. However, the tissue can then blister and is susceptible to gangrene. 

A cycle of thawing-refreezing is bad. Definitive help is important. 

The proper way to rewarm is with 40 degrees Celsius warm water to thaw the affected limb. It can be painful. Aspirin and NSAIDS could be useful to deal with pain.  There is some thought that the antiplatelet effect prevents thrombosis and further damage, and tPA is being studied as treatment (Hutchinson et al, 2019). There are prediction rules for the ultimate severity of damage (Cauchy et al, 2001), and the acute appearance doesn’t equal final disability.

Heat Exposure

Heat exhaustion reflects a spectrum of injury related to overheating, starting with heat cramps and heat syncope. Heat stroke is the end stage when people are unable to thermoregulate >104 F with CNS depression (Lipman et al, 2019). End organ damage, including brain, liver, and renal damage, can occur. Medications can predispose, including tricyclics, anticholinergics, amphetamines, ephedra, and antipsychotics. Older patients are prone.  Acclimatization, by gradually increasing exercise intensely over a couple of weeks, is warranted.

Drink to thirst to avoid hyponatremia (Bennett et al, 2020). Hyponatremia from excess water intake is more common than dehydration (i.e. hypernatremia) during exercise. 

Animal Bites

Bats

Bat bites are subtle, and rabies can also be transmitted through bat scratches. A high percentage of bats carry rabies. If bitten/scraped, start by washing the site with soap and water then pursue appropriate post-exposure prophylaxis. The CDC has a list of local contacts to help in the case of possible rabies exposure.  Dr. DeLoughery has personal experience with bat bites.

Snake Bites

Approximately nine thousand snake bites present to EDs in the USA annually, with about a third reflecting bites from venomous snakes (Kanaan et al, 2015).  However, very few people die of snake bites in the USA annually compared to other countries. Wikipedia keeps a list of fatal snake bites in the United States.  Most bite victims are young men 18-34 years old bitten on an extremity because they were messing with the snake…often while intoxicated. Even decapitated or dead snakes can bite and release venom due to residual bite reflexes.  Snakes, young men, and alcohol are the three component parts of the DeLoughery Triad of Doom. Taking a picture of the snake after a bite can provide information to the healthcare providers. Antivenom is the only definitive therapy; first aid in the field should not delay transfer to a facility where antivenom can be administered.  There can be cardiac effects, but complications are usually DIC and thrombocytopenia. Cobras and coral snakes have neurotoxic venom. 

Expert opinion: don’t mess with snakes.

Wound Care

Although simple, old fashioned direct pressure is a simple and often effective method to achieve hemostasis, tourniquets may have a role in acute bleeding (Drew et al, 2015). They need to be tight enough to stop arterial bleeding in addition to venous bleeding. Instructional videos abound. After around 2 hours, remove to see if the bleeding has stopped. Local hemostatics like QuikClot ®, which are bandages impregnated with procoagulants, are available. For big dirty wounds, prophylactic antibiotics can be used, especially if there is going to be a delay to definitive care. 

Wilderness first aid resources include: NOLS and  Advanced Wilderness Life Support

Clean wounds with soap and water!

Links*

1. De Gaulle by Julian Jackson 
2. Command and Control by Eric Schlosser
3. Auerbach’s Wilderness Medicine, 2-Volume Set 
4. Whatever book Paul said he was reading, sounds nerdy (The First Law Trilogy) 
5. Wilderness Medicine Society
6. Stop The Bleed: Home 
7. Into Thin Air: A Personal Account of the Mt. Everest Disaster by Jon Krakauer
8. National Outdoor Leadership School
9. Advanced Wilderness Life Support 
10. Inside the ER at Mt. Everest 
11. Annapurna by Maurice Herzog 
12. K2, The Savage Mountain: The Classic True Story Of Disaster And Survival On The World’s Second-Highest Mountain– by Charles Houston and Robert Bates

*The Curbsiders participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising commissions by linking to Amazon. Simply put, if you click on our Amazon.com links and buy something we earn a (very) small commission, yet you don’t pay any extra.

Goal

Listeners will learn the basics of wilderness medicine and how to approach a few common conditions. 

Learning objectives

After listening to this episode listeners will…  

1. Appreciate Wilderness Medicine as a medicine subspeciality and understand why or how someone might pursue this clinical focus area
2. Recognize signs and symptoms of high altitude sickness
3. Develop an approach to treating animal bites and injuries
4. Learn high yield tips for administering first aid in the wilderness including field hemostasis

Disclosures

Dr DeLoughery reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures.

Citation

O’Glasser AY, Gorth D, Deloughery T, Williams PN, Watto MF. “#242 Wilderness Medicine: Prfor Disaster”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list Original air date November 16, 2020.