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Float in the Snow - Avalanche Rescue Basics Part 1

Float in the Snow - Avalanche Rescue Basics Part 1

In the second installment of the Mountain Med Podcast by the UNM Austere and Mountain Medicine faculty, we discuss some basics of avalanche preparedness and basic buddy rescue. Avalanches impact patients in the backcountry who ski, snowboard, mountaineer, snowmobile or snowshoe in avalanche terrain and snowpacks that can often times be hard to predict. When rescuers enter these environments, they need the skills to execute quick, efficient and thorough searches and excavations of buried victims. In part 1 we also touch on the medical considerations of avalanche buried victims, and will get more in-depth with the medical component in part 2. Alright, stop reading and start listening!

Ophthalmology in the Wilderness (Part 1)

February 21, 2015

Ocular pathology is a topic that is often underappreciated in wilderness medicine education, despite vision being one of the major sensory inputs required for almost every task. Even seemingly benign issues such as a corneal abrasion, in a technical environment, can lead to debilitating pain and incapacitation. Impaired vision, even in one eye, can lead to decreased depth perception that can impact safe travel in difficult terrain, such as scree fields or ski touring. Consequently, the ability to diagnose and properly treat ophthalmologic issues in the backcountry is imperative. In part 1, we will cover all of the components of the complete eye exam. Depending on level of training, this may seem a little technical, but hang with me.
The Eye Exam
In a hospital or clinic environment, there are several aspects to the complete eye exam. Visual acuity and intraocular pressure are considered the “vital signs” of the eye. Extra-ocular muscle function, pupil size, shape, and response to light, and the examination of lids, lashes, and peri-orbital soft tissues make up the external part of the exam. Visual fields should also be assessed. Fundoscopy to evaluate the posterior chamber and retina, and a slit lamp exam to evaluate the cornea, anterior chamber, and lens are more advanced parts of the eye exam that take time and practice to develop proficiency. The response to topical anesthetic gives important information, as an improvement in pain generally guarantees that the pathology is external. Lastly, fluorescein staining to evaluate for any corneal defects such as abrasions or ulcerations finishes out the complete eye exam.
Outside of the hospital environment, the exam is more limited, however the components of the exam are still the same, even with a basic kit. A Snellen chart isn’t required for visual acuity – anything with print can be used to grossly estimate vision, with progression to finger counting, hand movement, and light and dark differentiation just like in the hospital. Acuity should be assessed with corrective lenses, but if the lenses are damaged or not available, a pin-hole can be easily improvised and provide an accurate exam. Increased intra-ocular pressure can be grossly assessed by pressing gently on the globes, feeling for asymmetry, firmness, or resistance to normal retropulsion. Extra-ocular muscle function, pupil exam, and evaluation of the external structures are no different from in a clinic, as long as a light source such as a flashlight or headlamp is available. Defects in pupil size and shape are usually obvious, but it is important to be able to know and look for a relative afferent pupillary defect. There are several causes, and almost all of them are vision threatening. A link to a video reviewing the exam can be found here. Fundoscopy is limited to those who choose to carry a direct ophthalmoscope in their kit, which isn’t unreasonable as there are lightweight options designed for austere environments. The slit lamp exam is impossible in the out of hospital arena, although there are small handheld potable devices available. Cutting a small slit in a thick piece of paper or tape does allow for a narrow beam of light that can be used to grossly assess anterior chamber angle and to look for corneal opacities. A topical anesthetic such as tetracaine should be part of a medical kit, although, just as with all medications, attention to environmental stability should be considered. Fluorescein staining is limited by the availability of either a UV light or a cobalt blue filter, however filters manufactured specifically for penlights are easily obtainable and there are several phone apps that have a cobalt blue screen light. One of the major limitations to performing an eye exam in the austere environment is getting out of the light into a dark enough area to be able to perform the exam, however going into a tent or covering up with a tarp or jacket can help to create a dark environment.
One final topic to discuss is ocular ultrasonography, which can be great adjunct to the eye exam. As ultrasounds platforms become smaller and more packable, it is much more feasible to bring one into the prehospital environment. Ocular ultrasound can give an immense amount of information, allowing for differentiation of some of the causes of acute vision loss, examining for glaucoma, penetrating foreign body, retrobulbar hematoma, increased intracranial pressure, and even pupillary response and extra ocular movements in a patient with extensive peri orbital edema. There are several great online resources regarding ocular ultrasound, which can be found here, here, and here. If available, ultrasound can help distinguish between the need to "call in the helicopter" versus having someone walk out or even stay on the expedition.
A thorough eye exam is essential in establishing a differential diagnosis for eye pathology, which can determine whether basic treatment is sufficient or if evacuation is required. Not all parts of the exam are required in every situation, but knowing how to perform an eye exam is crucial. If ultrasound is something that is available, it can be very useful. In part 2, we will get more into the meat with a discussion on the approach to the eye complaint and management of different common conditions seen in the wilderness environment.

Out of state sports physician: are you covered?

Although this is not a classic mountain medicine topic, it is pertinent to anyone who travels out of state to provide medical care. One of my specific areas of interest is providing medical coverage for ultra-endurance events, which are often outside of my home state. This has caused some issues regarding to proper licensing.
Medical licensing in the United States is sanctioned on a state-by-state basis. This makes it challenging for physicians who often travel out of their home state to perform medical care. Common examples include sports team physicians, event physicians, and physicians who want to volunteer in high need situations (i.e. Hurricane Katrina). Complicating matters are that each state has its own rules and regulations regarding out of state physicians. Viola et al investigated this issue with regards to sports team physicians in an article published in the British Journal of Sports Medicine in 2013 where they surveyed 58 medical boards, with information obtained on 54. Only 18 medical boards specifically allow for physicians to travel with their team under their out of state medical license. 27 states specifically do not allow the practice of medicine without a license in their state. The remaining nine either do not address the issue or have non-relevant “consultant” laws. In the same publication, 20 malpractice insurance groups were surveyed, and of the 11 that responded, only 2 stated that they would provide coverage regardless of individual state licensing regulations. Five stated they would provide coverage out of state, but only with appropriate state licensure. Four actually responded that regardless of licensure or state requirements, they WOULD NOT provide coverage outside of the physician’s home state. This means that 67% of the time, a traveling sports physician is practicing without a valid medical license, and frequently without malpractice coverage.
An investigatory report performed by the Federation of State Medical Boards (FSMB) looked into the same issue with similar conclusions. All 68 state medical boards were investigated, with only 20 boards that have an applicable exemption from licensure. Aside from just team sports physicians, the FSMB workgroup look at other various out of state situations: youth camp physicians, volunteers to underserved/underinsured populations, and other groups not pertinent to this discussion. Recommendations to the state medical boards are made at the end of the report, encouraging the boards to consider updating their policies and giving exemption to team physicians, and encouraging issuance of special purpose licenses in other situations where required. Notably, the first author listed on this paper is a member of the Arizona Board of Osteopathic Medical Examiners, which is one of the boards that does not specifically have wording considering team physicians, and requires either a full medical license or an Arizona state licensed sponsoring physician plus a $300 Locum Tenens license. It is reassuring to see that the states are aware of their own issues and seeking to find a solution.
Thankfully, with the FSMB report and other publications, these issues are coming more to the forefront. The American Medical Society of Sports Medicine (AMSSM) is currently trying to push legislation for a federal patch to the licensing regulations allowing for a global exemption. Individual physicians will need to check with their own malpractice insurers concerning out of state coverage, and obtain additional coverage where necessary. For the time being, those of us who occasionally cover sporting events out of state need to be aware of the issues, and check with each state in advance to ensure we do not risk our careers unknowingly. I would appreciate hearing any other thoughts or feedback in relation to this issue.

  1. Viola T, et al. A Survey Of State Medical Licensing Boards - can the travelling team physician practice in your state. Br J Sports Med 2013;47:60–62. doi:10.1136/bjsports-2012-091460
  2. Steingard, et al. Report Of The FSMB Workgroup On Innovations In State Based Licensure. Apr2014

Wilderness Spinal Considerations - A Podcast

January 21, 2015

Welcome to the UNM Austere and Mountain Medicine Blog! We are excited to bring our greater audience up-to-date knowledge pertaining to the field of mountain rescue, wilderness medicine, and all things austere. This blog is intended for wilderness medicine providers and mountain rescue professionals as well as plain-ol mountain lovers who want to gain knowledge about emerging standards in the management of emergencies in the backcountry. We hope to keep our readers (and listeners) current on hot topics in wilderness medicine, backcountry travel, and emergency preparedness.
Our first Blog post addresses the commonly discussed and often heated topic of spinal precautions in the wilderness. To backboard or not to backboard, has been a question that has seen significant interest in the past decade from the world of EMS (Emergency Medical Services) and emergency departments across the globe. The discussion is further complicated when we encounter a potentially spine injured patient in hazardous terrain or complicated weather, and the implications of applying and maintaining "spinal immobilization" are much greater than in the ED, or even the streets of EMS.
To address this topic, we present our first of many to come podcasts! Listen in to Dr. Darryl Macias, Dr. Aaron Reilly, Dr. Jenna White and Jason Williams discuss where the literature is leading us in the management of possible spine injuries in the backcountry.
Hope you enjoy it!!!!!


  • Wilderness Medical Society practice guidelines for spine immobilization in the austere environment.
  • Robert Quinn, Jason Williams, Brad Bennett, Gregory Stiller, Arthur Islas, Seth McCord, Wilderness Medical Society: Wilderness Environ Med. 2013 September; 24(3): 241–252
  • The Long Backboard vs the Vacuum Mattress. McDonald N, Webster M, Orkin A, VanderBurgh, Johnson DE Prehosp Disaster Med. 2014 Feb;29(1):110.
  • Comparison of a SAM splint-molded cervical collar with a Philadelphia cervical collar. McGrath T, Murphy C. Wilderness Environ Med. 2009 Summer;20(2):166-8.

Ophthalmology in the Wilderness (Part 2)

Ophthalmology in the Wilderness (Part 2)

March 13, 2015

The Approach to the Eye Complaint
The Wilderness Medicine Society’s practical guidelines for treatment of eye injuries and illnesses has a great approach to the eye complaint, and I have found it to be the most optimal way to break down the differential diagnosis and guide the rest of the exam. This method divides eye pathology into three groups: the white eye, the red eye, and eye trauma.
The White Eye
Also known as the “quiet eye”, the white eye generally refers to painless vision loss. Peri-orbital pathology is included in this section, as there is no inflammation of the actual eye structures. Painless vision loss is an ominous symptom, and is often caused by a vision threatening process. The differential includes central retinal artery occlusion, central retinal vein occlusion, retinal detachment, vitreous detachment, vitreous hemorrhage, and optic neuritis. Without the ability to perform fundoscopy, it is impossible to differentiate the actual pathology, although ultrasound can be extremely helpful. A RAPD (see part 1) can be present, but is not specific for a specific diagnosis. For suspected retinal artery occlusion, simple maneuvers such as globe massage, carbon dioxide re-rebreathing, and high flow oxygen, if available, can be attempted. Ultimately, all painless vision loss should be emergently evacuated as determining the etiology is extremely difficult in the austere environment.
Causes of peri-orbital inflammation vary from benign skin and soft tissue pathologies to vision and life threatening infections. Knowing how to distinguish between them is essential. Peri-orbital etiologies include pre-septal cellulitis and dacrocystitis. These are both simple infectious processes that are easily treated with antibiotics and symptomatic management. Hordeola and chalazea are acute inflammatory processes of the eyelids and can be treated symptomatically with warm compresses and lid hygiene. Orbital cellulitis, however, is an infectious process that involves the structures of the orbit, and can progress to cavernous sinus or central nervous system infections. The presence of visual disturbances, painful limitations in extra ocular motion, proptosis, increased intra ocular pressure, or systemic signs of infection such as a fever clinically distinguish it from an extra-orbital process. These patients require IV antibiotics and emergent evacuation.
The Red Eye
There are multiple causes of a non-traumatic red, painful eye. A recommended approach that I find useful both in the austere environment and the clinical setting is to use simple testing to divide the differential into distinct categories. After performing a basic eye exam, the next step is to apply a topical anesthetic such as tetracaine and observe for improvement in symptoms. Lack of improvement indicates that the pathology is likely not isolated to the surface of the eye. This differential includes iritis/uveitis, scleritis, and acute angle closure glaucoma, and requires emergent evacuation. For those with improvement after the tetracaine, the fluorescein testing is performed. Etiologies such as conjunctivitis, blepharitis, and foreign bodies are generally improved with a topical anesthetic but do not have fluorescein uptake. If there is uptake, corneal erosion, corneal ulcer, UV keratitis, and herpes simplex keratitis should be considered. Of these, generally only herpes keratitis requires emergent evacuation, however in certain settings, urgent evacuation should be considered if the proper ophthalmologic evaluation and treatment are not available.
Traumatic Eye Injuries
Orbital and ocular trauma can range from mild to vision threatening, and any direct trauma should be thoroughly evaluated for emergent conditions. Retro orbital hematoma, globe rupture, complicated orbital fractures, complex lid lacerations, hyphema, or chemical injuries require emergent evacuation. Field treatment focuses on symptom control, preventing further damage, administration of parenteral antibiotics or steroids. If it is within the provider’s scope of practice, a clinically suspected retro orbital hematoma should have a lateral canthotomy performed. Orbital impalement objects should be stabilized and left in place. Often times covering both eyes will prevent eye movement and further damage. For any chemical injury, copious irrigation should be performed. All of these patients should be emergently evacuated for definitive care.
Simple corneal abrasions, keratitis, or corneal frostbite can be managed non-emergently pending the ability to continue safely in the current environment. Topical antibiotics can help prevent infection, and the patients should be frequently re-evaluated for any signs of disease progression.
In summary, it is important to know how to perform an eye exam and evaluate for a vision threatening process. Breaking the differential down into the white eye, the red eye, and eye trauma can help to guide treatment and evacuation priorities. Basic eye exam equipment and medications should be considered when putting together a medical kit for an expedition. Any vision threatening pathology should be evacuated emergently, and in non-emergent situations, consideration should be given to the limitations of decreased visual acuity or monocular vision. The Wilderness Medical Society Practice Guidelines for Treatment of Eye Injuries and Illnesses in the Wilderness is a great resource for wilderness ophthalmology and give a thorough overview and also goes into treatment recommendations for the conditions listed above. As always, comments and questions are welcome.

MountainMed Podcast Episode 3 Hot Hot Heat -Update on the Pathophysiology and Treatment of Heat Illnesses

MountainMed Podcast Episode 3 Hot Hot Heat -Update on the Pathophysiology and Treatment of Heat Illnesses

July 01, 2015

Dr. Darryl Macias and Dr. Aaron Reilly are back to talk about heat illness. It is the summer months, and if you are anywhere south of the Alaskan tundra in the Northern Hemisphere, you are more likely than ever to come across a patient presenting with heat illness. These two faculty physicians at the UNM Austere and Mountain Medicine program talk about the current literature, current understanding of the pathophysiology, and the most relevant considerations for treating patients with heat illness in the backcountry. Join us and our state of the art sound-effects for 20 or so minutes of information and entertainment!

  1. Lipman GS, Eifling KP, Ellis MA et al. Wilderness Medicine Society practice guidelines for the preventions and treatment of heat related illness: 2014 update. JWildEnMed; 2013;25(4):S55-65.
  2. Auerbach, P. (2011). Wilderness Medicine (6th ed., pp.215-239). Mosby.
  3. Noakes TD. A modern classification of the exercise-related heat illnesses.JSciMedSport; 2008 Jan;11(1):33-9.

Medicine and Science in Ultra Endurance Sports – an update from the 2nd annual medical conference

July 01, 2015

The Medicine and Science in Ultra Endurance Sports conference is an event put on in conjunction with the Western States Endurance Race (WSER) and is geared towards the most recent literature in ultra endurance sports. As it is estimated that there were over 50,000 ultra finishers last year, and new races are frequently popping up all over the world, developing data driven approaches to these events is a necessity. It’s a great conference for anyone associated with ultra endurance sports, including medical directors/providers, race directors, volunteers, coaches, and athletes.
Much of the content revolved around observational data of symptoms experienced during ultra events. Not surprisingly, nausea, bloating, and vomiting were the most commonly reported symptoms during an ultra. These generic symptoms are generally termed “exercise associated gastroparesis”, which is presumptively caused by reduced perfusion to the splanchnic/mesenteric circulation from shunting of blood that leads to a decrease in peristalsis. This was also the number one reason for non-finishers to drop out in the cohorts studied. Musculoskeletal issues, blisters, respiratory complaints, and dehydration were generally the other most common reasons for competitors to seek medical care. Interestingly, in one study, 10% of those that sought medical care were non-competitors (volunteers, pacers, etc).
As expected, exercise associated hyponatremia was a big topic. The risk primarily comes from two major factors: over hydration and SIADH. Consistent with the teaching over the past few years, managing dehydration by drinking according to thirst is still the top recommendation for avoiding both significant dehydration and dilutional hyponatremia. Electrolyte tablets don’t prevent cramps, nausea, or protect against hyponatremia, and can actually increase the thirst mechanism causing over hydration, so are now generally recommended against.
Acute Kidney Injury (AKI) in ultra runners is caused by three main mechanisms: dehydration (most common), rhabdomyolysis (most serious), and NSAIDs (most dumb) as described by Dr. Weiss. The key points were to avoid NSAIDS, and treat rhabdo with fluids. Dehydration, even with significant weight loss during the event, was not tied to performance, and clinically insignificant AKI is not unexpected in ultra runners.
Interestingly, there were several presentations on psychology. Dolores Christianson is a PhD student in psychology that is doing her thesis on recognizing the psychological difference between finishers and non-finishers. Although there is a lot left to study, and the mindset of a runner during a race is difficult to assess outside of real time, it seems that those that focus more on the race and how they are feeling as opposed to abstract, unrelated topics is more characteristic of separating finishers from non-finishers. Also, the unhappy triad of pain, nausea, and worsening mood seem to lead to a downward spiral toward the DNF column. Lastly, 2 ultra runners gave personal accounts of their struggles with depression, which was very a powerful look into the struggles of recognizing, accepting, and coping with their mental illness.
Dr. Joslin gave two talks, the first on considerations for the medical screening of ultra-endurance athletes. See this article published in the Journal of Sports Medicine. The second talk was on the management of the seriously ill or injured ultra marathoner, including trauma, anaphylaxis, hyponatremia, and several other potentially fatal conditions. John Vonhof of Fixing Your Feet gave a fantastic lecture of blister care. Dr. Hoeg gave a presentation on Ultramarathoner’s Eye, which is a degradation of visual acuity thought to be related to corneal edema, although it is poorly studied or understood. See this article in Wilderness and Environmental Medicine. Dr. Badowski spoke on recovery after exercise, and the paradigm is shift from a RICE approach to CAM – compression, activity (low intensity), and massage. She is collecting data during this year’s WSER to help better understand the potential benefits of different modalities.
There was an interesting talk given by Dr. Kurland on acute respiratory issues in ultra marathoners. He focused on exercise induced bronchospasm and vocal cord dysfunction (VCD). VCD is much more common than recognized, and characterized by severe respiratory distress with stridor without wheezing. It is exacerbated by physical or emotional stress, and ceases in a sudden manner with relaxation. As opposed to most causes of respiratory distress, the oxygen saturation is normal, and there is often a history of previous episodes. Recognition of VCD is key, as these individuals are often (inappropriately) intubated because of the severity of their presentation.
Overtraining Syndrome – yes, it’s a real thing. Interestingly enough, this article from Outside Magazine was going around social media in the weeks leading up to the conference, and was highlighted in a case report and as part of a couple of other presentations. It is characterized by generalized fatigue and exercise intolerance lasting >4 weeks that cannot be attributed to another cause. More information can be found here.
Each day of the conference had exhibited small groups on medical kits (Joslin) and foot care (Vonhof), and Dr. Hoffman gave presentations on how to do research in a race setting and discussed some of the medico-legal aspects of performing medical care at ultra events. Unfortunately I wasn’t able to attend these groups, but I’m sure they were excellent.
Lastly, the conference was held at Squaw Valley Ski Resort, which is a beautiful area with great terrain for hiking, trail running, mountain biking, and only about 10 miles from Lake Tahoe (see pics below). The wildflowers were in bloom and the weather was beautiful.
Overall it was a great conference and one that I would recommend to anyone associated with the ultra community. There is still much to be learned about the physiological changes and injury patterns in ultra-endurance athletes, and with 50,000 runners per year, it behooves us a medical community to continue to study this population and keep them healthy both on the course and in their day-to-day life.

Hyperthermia and Heat-Related Illness

May 10, 2015
As summer gets closer, so does the risk for heat injury. In this post we will review heat injury, as well discuss some of the misconceptions in regards to hyperthermia and other classic heat related illnesses.
First off, it needs to be understood that hyperthermia does not equal fever. Fever is a desired change in homeostatic baseline core body temperature as a means of defense against infection, and body temperature rises because the hypothalamus wants it to. In contrast, hyperthermia is an undesired net gain of heat which causes an increase in body temperature in spite of the hypothalamic set point. In essence, heat gained > heat lost.

Heat transfer occurs by four primary mechanisms:

  1. Evaporation: heat liberation by liquid changing into a vapor (sweating)
  2. Radiation: heat transfer from a warm object into the surrounding environment (solar warmed rock in cool air)
  3. Conduction: heat transfer from a warm object by direct contact with a cooler object (warm hand on a metal chair)
  4. Convection: moving current removes radiated heat from the area adjacent to the body (this is prevented by a wet suit or a down jacket that keeps the radiated warmth next to the body)

Heat accumulation has both internal and external components. Routine metabolism generates heat through exothermic reactions leading to approximately enough heat to increase body temperature by 1.1°C per hour. Intense exercise can increase this metabolic heat production up to 20x. Heat can also be gained from the environment through the heat transfer mechanisms discussed above. Normally, the body deals with this heat accumulation through sweating (evaporation) and vasodilation of the skin vasculature (radiation). Heat can also be dissipated through respiration, although this in minimal in comparison to dogs which can lose a good deal of heat through panting. The environment can play a large role in our ability to lose heat. As humidity reaches 100%, sweat evaporation is impaired as there is no "room" in the air for the vaporized sweat molecules. Also, once the ambient temperature reaches 35°C, the temperature gradient begins to favor heat retention, and as it increases, can lead to heat gain.
As body temperature rises, more blood is shunted to the periphery in attempts to dissipate the excess heat. This is done so at the expense of core perfusion. The first organ to suffer hypo-perfusion is the mesentery, which leads to loss of microvilli in the gut and endothelial compromise. Endotoxins, normally contained in the intestines, are able to cross into the blood. Intracellular toxins from muscle breakdown also release into the bloodstream. This toxemia leads to a massive systemic inflammatory response (SIRS). There is also some degree of direct thermal injury, but this only occurs at extremely high temperatures (>42°C). Temperatures of this magnitude can cause intracellular protein deformation and mitochondrial dysfunction, as well as apoptosis and cell death. Eventually, if the process is not halted and reversed, multi-organ injury occurs, and ultimately death.
There are several factors that help to assess the risk for heat injury. These should always be considered, especially when any activity is scheduled, from sporting events, to military training, to expeditions.

These risk factors can be broken down into four categories:

  1. Individual factors: Overall fitness, BMI, chronic medical conditions, and hydration status both pre and during exertion all play a big role. Medications that interfere with the response to heat, such as those that prevent increases in heart rate (B-Blockers, Calcium Channel Blockers, etc.), decrease intravascular volume (diuretics), reduce vasodilatation (nicotine), or increase metabolic production (caffeine, SSRIs, amphetamines, cocaine, etc.) all predispose to heat injury. Deficiencies in the ability to sweat (ichthyosis, scars) can also play a role. The biggest risk factor for developing heat injury is previous history of heat injury, and should be taken seriously when considering medical clearance for a particular event.
  2. Activity: Metabolic Thermal Production = Intensity + Duration. Simply put, higher exertion levels for longer periods of time leads to increased heat production, which will need to be dissipated.
  3. Environment: Several environmental factors come into play when assessing heat transfer. Ambient temperature, solar radiation, humidity, and wind speed can all affect the heat transfer mechanisms and lead to a significant decrease in the ability to dissipate heat. Wet bulb globe temperature (WBGT) takes all of these factors into play and can give a baseline risk assessment for development of heat injury.
  4. Clothing and Equipment: This comes into play in sports like football where pads and helmets, or military personnel required to wear full coverage uniforms with heavy flak, can significantly inhibit heat loss mechanisms.

Taking all of these factors into account can help to both predict and mitigate the risk of significant heat injury.
Acclimation can help to reduce the likelihood of heat injury, however it is a process. General recommendations are to exercise in a hot environment, 90 minutes per day for 14 days. Acclimation leads to several changes in the physiological response to heat stress, including cardiovascular, metabolic, and biochemical protective factors. Cardiovascular affects include earlier heart rate response and lower upper exertion heart rate, preservation of cardiac output despite peripheral vasodilation, and better heat-loss mechanisms. Sweating starts sooner, with a significantly lower concentration of sodium in the sweat which helps to maintain electrolyte and fluid balances. In response to the heat stress during acclimation, heat shock proteins (HSP) are developed. There are multiple types of HSP that fulfill separate roles, but the basic function of protective HSP is to stabilize the intracellular environment to maintain protein conformation and function, and to help break down deformed and rebuild proteins required for intracellular processes and mitochondrial functions. All of these changes lead to better performance in hot environments as well as decreased risk of developing heat injury.

Here are several conditions that have be classically termed "heat related illness".

  1. Heat rash (miliaria rubra): pruritic, vesiculo-pustular rash generally in areas covered by clothing. This results from clogging and subsequent inflammation of sweats glads. Prevention consists of wearing wicking clothing and keeping the skin clear of pore-clogging dust/dirt. It generally resolves spontaneously, but topical anti-itch therapies may help with symptoms.
  2. Heat edema: dependent swelling of the distal extremities that occurs during prolonged exercise, primarily due to peripheral vasodilation and increased hydrostatic pressures leading to vascular leak. Rings and other constrictive items should be removed, however there is no other necessary therapy. The edema resolves once exertion ceases and with elevating the extremities.
  3. Heat cramps: muscle spams that can occur in single muscles or in multiple large muscle groups. There are several theories on the pathophysiology, including hypovolemia from dehydration, electrolyte abnormalities, or fatigue at the neuromuscular junction, however nothing has panned out in the literature. The cramps tend to improve with rest, stretching, hydration, and electrolytes, but will occasionally persist and require cessation of activity.
  4. Heat syncope: brief loss of consciousness with rapid return to baseline associated with exertional activity. This usually occurs just after an athlete finishes their activity, with a sudden loss of pumping action from the leg muscles that leads to orthostatic pooling in the lower extremities leading to a drop in right atrial pre-load. This induces a reflex skeletal muscle vasodilation and decrease in cardiac output (Barcroft/Edholm reflex) and vasogenic syncope. Evaluation of other cases of syncope should be investigated, however the majority of finish line collapses can be attributed to this reflex. Treatment consist of placing the patient supine with their lower extremities elevated. Very rarely are IV fluids indicated, and no further therapies are required. If there is a delay in return to baseline or any other situation that points to a more complicated process, further evaluation and treatment is warranted.
  5. Heat exhaustion: generalized fatigue, nausea, and cramping related to exertion. This may be due to a combination of dehydration, electrolyte imbalance, and caloric depletion from prolonged effort. Rest, repleting calories, oral hydration, electrolyte replacement, and passive cooling with close monitoring for worsening symptoms if indicated. There is some thought that heat exertion will progress to heat stroke if not recognized and treated.

There is some controversy regarding the so called "heat associated illnesses", as they require neither hyperthermia nor a hot environment to occur. All have been documented in normothermia and in cooler temperatures, leading to a call to reclassify and rename them as exertional or exercise associated illnesses as opposed to heat related. This would prevent early dismissal of the possibility of these etiologies in moderate temperatures or in the absence of elevated body temperature, and better indicate the pathology in the name.
True heat injury is referred to as Heat Stroke. Three things are required for the diagnosis of heat stroke: 1) Hyperthermia >40°C, 2) CNS manifestations, and 3) prolonged exposure to heat or exertion. There are two types of heat stroke: Classic and Exertional. Classic heat stroke occurs with prolonged exposure to high ambient temperatures in the absence of significant exertion. It generally occurs in those limited abilities to dissipate heat or change their environment in order to prevent heat gain, such as the young, the old, and the bed bound. Exertional heat stroke occurs in the setting of prolonged intense exercise, and is more likely in hot temperatures but can occur in cooler temperatures if other factors are present.
Recognition of heat stroke and early institution of treatment is directly related to outcome. Morbidity and mortality is directly related to the duration and magnitude of the heat stress. If hypotension occurs, mortality increases 3x from 10% to over 30%. After assessing the ABCs, the next step is to stop heat gain and start active cooling. Moving the patient off of hot rocks or asphalt and into the shade will prevent further heat gain by conduction and radiation. There are several active cooling methods, however the best by far is submersion in an ice bath. If an ice bath is not available, a cold stream or lake is an option, with care taken to prevent the patient from completely submersing. Other less optimal options include misting with spray bottles while fanning the patient to help with evaporative and conductive heat loss, or cold packs in the groin, axillae, and neck to cool the large, superficial vasculature. There was also a small study published in 2014 about placing cold packs on the cheeks, palms and soles which showed better cooling rates than the traditional placement sites. Ice packs are always preferable to chemical cold packs, if available.
It is important to assess for other causes of altered mental status (AMS). Although hyperthermia and CNS manifestations are required for the diagnosis of heat stroke, not all hyperthermia and AMS is heat stroke. A study monitoring core temperatures in marathoners showed several asymptomatic runners with core temperatures >40°C, and two >41°C without symptoms of heat illness. Hypoglycemia and exercise associated hyponatremia (EAH) should be ruled out with blood glucose and sodium levels, if possible. Dehydration, rhabdomyolysis, and acute renal failure with uremia can occur. If altitude is a factor, high altitude cerebral edema should be considered. Metabolic (thyrotoxicosis) or toxicologic hyperthermia (silicates, serotonin syndrome, neuroleptic malignant syndrome) are also possibilities. Make sure to keep a broad differential while instituting cooling mechanisms.
Transport to a critical care capable facility should take place as soon as possible. IV hydration should be performed with caution unless EAH has been ruled out with sodium testing, however resuscitation should be initiated in the setting of hypotension to prevent further hypo-perfusion and organ damage. Cooling should be continued in hospital until 39°C. Evaluation for end organ injury and intensive supportive care are required. There is no role for antipyretics in heat stroke, as the hypothalamic set point is already at baseline, and NSAIDs and acetaminophen (paracetamol) can worsen organ injury.
In summary, heat stroke is the only true heat injury, and must be recognized and treated early. Submersion is the best form of cooling, however other methods should be used if submersion is not available. Emergent transfer to definitive care is imperative. The other "heat related illnesses" are actually exertion related conditions, and can generally be treated in the austere environment without the need for evacuation depending on the circumstances.


  1. Lipman GS, Eifling KP, Ellis MA et al. Wilderness Medicine Society practice guidelines for the preventions and treatment of heat related illness: 2014 update. JWildEnMed; 2013;25(4):S55-65.
  2. Auerbach, P. (2011). Wilderness Medicine (6th ed., pp.215-239). Mosby.
  3. Noakes TD. A modern classification of the exercise-related heat illnesses. JSciMedSport; 2008 Jan;11(1):33-9.

MountainMed Podcast 4 - Climbing Injuries

MountainMed Podcast 4 - Climbing Injuries

August 13, 2015

In this months podcast, Dr. Darryl Macias familiarizes us with the different types, difficulties and techniques of rock climbing, including a discussion of traditional rock climbing vs. sport climbing. This topic becomes a jumping point to discuss the most commonly encountered injuries experienced by climbers, focusing in on injuries to fingers, hands, wrists and elbows. Whether you are a climber or a mountain rescuer, this podcast should further inform you about what to expect in terms of injuries, and how to assess and heal them.

MountainMed Podcast 5 - High Altitude Acclimatization Part 1 - The Short Game

MountainMed Podcast 5 - High Altitude Acclimatization Part 1 - The Short Game

December 26, 2015

Dr. Darryl Macias is back with another edition of our MountainMed Podcast. This month he addresses the short term adaptations that occur during acclimatization to high altitude.
Give it a listen and give us some feedback with any questions you may have!


  1. Luks AM. McIntosh SE. Grissom CK, et al. Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness. Wilderness and Environmental Medicine, 21: 146-155 (2010)
  2. Bartsch P, Swenson ER. Acute high-altitude illnesses. N Engl J Med. 2013 Oct 24;369(17):1666–7.
  3. Macias DJ, Bartsch: The "OLD HAG" mnemonic discussion. At X World Congress of High Altitude and Physiology, Bolzano Italy, May 28 2014 (submitted to High Altitude Medicine and Physiology)
  4. Subudhi AW, Bourdillon N, et al. AltitudeOmics: The Integrative Physiology of Human Acclimatization to Hypobaric Hypoxia and Its Retention upon Reascent. PLoS One. 2014; 9(3): e92191.

1st Masters in Mountain Emergency Medicine - International Collaboration Conference

What a week we had October 5th - October 11th! 19 physicians from Italy, Slovakia, Chile, Brazil, the U.S. and the Netherlands joined in New Mexico for a week of conference and practical training in Mountain Emergency Medicine. This collaboration marked a milestone in international collaboration for the UNM Austere and Mountain Medicine program, and we are left feeling grateful to host such an exceptional group. Each physician represents a locus of progression that continues to advance the level of medical care delivered to sick patients in the most challenging mountain environments.
We thought our readers might like to read a description of our activities, accompanied with plenty of photos and a few snippets of video documenting the week. We anticipate this is just the first of many opportunities to engage other leaders of mountain medicine from around the world, sharing ideas and pushing the standards for rescue in the mountains.

Arrival and Conference

After a hand full of trips to the Albuquerque International Sunport, the group assembled on Monday at the UNM School of Medicine for an afternoon of lectures. The timing of the trip was great, and many participants saw the sky filled with balloons that were flying as a part of the Albuquerque International Balloon Fiesta.

Here is a list of the lecture topics and presenters for this afternoon of conference...

  • History of Rescue Operations in the United States - Jason Williams, NR-P, DiMM, Director UNM Mountain Med
  • Snake Bites and Stings of the Desert Southwest - Darryl Macias, MD, FACEP, DiMM, Primary Faculty UNM Mountain Med; Director UNM Wilderness, Austere and International Emergency Medicine Fellowship and Clerkships
  • Lightning Injuries - Dane Abruzzo, NR-P, DiMM, Primary Faculty UNM Mountain Med
  • High Altitude Cultures and Adaptation - Joe Alcock, MD, Faculty UNM Mountain Med, UNM Evolutionary Biology
  • Climbing and Rescue Equipment and Systems Research - Pull Testing - UNM Faculty

Conference Day 2 - Special Guest Dr. Ben Levine

Day 2 was packed with didactics and we were happy to have Dr. Ben Levine as a guest lecturer. Dr. Levine has been a leading researcher in the field of exercise science for over 2 decades, and focused his talks for us around high altitude adaptations in athletes. He is a practicing cardiologist at UT Southwestern, and the current director & original founder of the Institute for Exercise and Environmental Medicine. Also on the docket was Marc Beverly, PA-C, UIAGM Mountain Guide and PhD in Exercise Science, who presented some preliminary findings from his original research investigating Harness Suspension Stress..

Here is a brief synopsis of all the lectures that day:

  • Heat Illness and Hyponatremia - Trevor Mayschak, NR-P, Primary Faculty UNM Mountain Med, Grand Canyon SAR Paramedic
  • State-of-the-Art Training at Altitude - Ben Levine, MD, Professor UT Southwestern, Director IEEM
  • Lightning Injuries - Dane Abruzzo, NR-P, DiMM, Primary Faculty UNM Mountain MedHarness Suspension Stress - Ben Levine, MD, Professor UT Southwestern, Director IEEM
  • Lawful/Unlawful Training Methods - Ben Levine, MD, Professor UT Southwestern, Director IEEM
  • Oxygen and the Gut Microbiome - Implications for Mountaineers - Joe Alcock, MD, Faculty UNM Mountain Med, UNM Evolutionary Biology
  • Taos Ski Valley Case Reports - Carl Gilmore, EMT-I, Taos Ski Valley Ski
  • Dislocations, Reductions and Fractures - Darryl Macias, MD, FACEP, DiMM, Director UNM Wilderness, Austere and International Emergency Medicine Fellowship and Clerkships; Primary Faculty UNM Mountain Med
  • EMS Systems with the US Border Patrol - Russ Baker, DO, UNM EMS Fellow

The Grand Exodus - To the Grand Canyon!

On Wednesday morning we packed the vans and headed out to the Grand Canyon. The focus here was on practical exercises, ranging from practice utilizing the iStat for heat related illnesses to High Angle Rescue Evolutions to a helicopter med-evac demonstration. Photos and video do these days justice, so take a look below...

As was perfectly stated in the video by Dr. Luigi Festi, this is only the beginning, and the faculty at the University of New Mexico Austere & Mountain Medicine program couldn't be more excited to see what the future has in store. We are happy to continue meeting and working with individuals from around the world that share the vision of what mountain rescue and mountain medicine can become.
Feel free to ask any questions in the comments below about this adventure, our programs, or the many partners we have met through this process.
- UNM Austere and Mountain Medicine Team -

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