Category Archives: Exposure

Acclimation, Altitude Science, Athletic Training, Backpacking, Exposure, Health, High Altitude, High Altitude Training & Fitness, Mountaineering

When Altitude gets High, does Stroke get higher?

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Does altitude increase or decrease risk of strokes? As one review put it, “Due to limited literature, lack of large series, and controlled studies, the understanding of stroke at high altitude is still sketchy and incomplete”. What is clear is that stroke at high altitude can often be misdiagnosed (or underdiagnosed), due to the similarity of initial presentation with high altitude cerebral edema (HACE). Both conditions present with imbalance or ataxia, and both can present with focal neurological deficits.  There are few large urban populations at high altitude (Addis Ababa in Ethiopia is 7,726 ft), so medical providers have fewer resources.  Without the ability to perform neuroimaging with a CT scan or MRI in a timely manner a diagnosis of HACE vs. stroke could be uncertain. HACE often causes global cerebral dysfunction, differentiating it from an early stroke before the onset of focal symptoms can and often does prove challenging. 

While the prevalence of strictly hemorrhagic and ischemic strokes at high altitude remains murky, it is known that exposure to high altitude can result in conditions such as TIA, cerebral venous thrombosis (CVT), seizures, and cranial nerve palsies. Most of the research that has been done on strokes is focused on “moderate” and “high” altitudes, as opposed to “very high” or “extremely high” altitudes. As such, there is very little research on populations living at 3500m or higher. There was at least one tangible piece of evidence indicating that the higher the elevation, the earlier the mean onset of stroke – Dhiman et al. (2018) found that at an elevation of 2,000m, the mean age of onset of stroke was 62 years. The age decreased to a mean of 57.9 years at 2,200m in another study (Mahajan et al. (2004)). Yet another study (Razdan et al. (1989)) found 10.9% of the patients in their sample suffered strokes aged < 40, though this was at an altitude of only 1,530m. Some reports suggest higher stroke prevalence at higher altitudes, and at a strikingly young age – between age 20 and age 45.

Student presentation on stroke at altitude at Colorado Medical Society meeting 2022

There have been mixed results on the effect that altitude has on strokes. One systematic review study found 10 studies displaying an increase in stroke prevalence with higher altitude, 5 other studies showing that altitude was actually protective against stroke, and 2 studies in which the results were ambiguous. This study and other sources alluded to the fact that poorer stroke outcomes at higher altitude may be due to polycythemia and increased viscosity of blood. Specifically, Ortiz-Prado et. al noted that “living in high-altitude regions (>2500m) increases the risk of developing thrombosis through hypoxia-driven polycythaemia which leads to a hypercoagulation unbalance”, which was associated with increased risk for stroke. Ortiz-Prado et. al noted that most of their info came from “very few cross-sectional analyses”. These analyses did find “a significant association between living in high-altitude regions and having a greater risk of developing stroke, especially among younger populations”. When the effects of altitude on stroke were broken down by race (Gerken, Huber, Barron, & Zapata, 2022) it was found to be protective in some populations (Whites, African Americans), but detrimental in other populations (Hispanics, Asian-Pacific, and American-Indian). Going back to the work of Ortiz-Prado et. al, altitude increased the risk of stroke at elevations above 3500m, when the time spent at this elevation was at least 28 days, and more so in younger persons (below the age of 45). At lower elevations, between 1500m and 3500m, increased / easier acclimatization and adaptation to hypoxia seemed to offer protective effects against the risk of stroke. Chronic exposure to hypoxia at high altitude triggers adaptive / compensatory mechanisms, such as higher pulmonary arterial flow and improved oxygen diffusing capacity. Ortiz-Prado et. al concluded that a window of ideal elevation seems to exist – below an altitude of 2000m the adaptive mechanisms do not seem to be sufficient to yield a protective effect – however, above 3500m, adaptive mechanisms may actually become maladaptive (excessive polycythemia & blood stasis), yielding a higher risk for stroke. A lack of any adaptation (i.e. in altitude naïve persons) was even more detrimental at such high altitudes, with the authors concluding that “above 3500–4000m, the risk of developing stroke increases, especially if the exposure is acute among non-adapted populations” (Ortiz-Prado et. al, 2022).

Strokes are more common in males compared to females, and this held true at altitudes of 3380m, 4000m, and 4572m. In addition to the standard vascular risk factors such as hypertension, smoking, and diabetes, the higher incidence of polycythemia in persons living at high altitude is thought to play a role. One study (Jha et al. (2002)) found that 75% of the patients in their sample who had suffered strokes had some form of polycythemia – this was at an altitude of 4270m. (Dr. Christine Ebert-Santos of Ebert Family Clinic in Frisco, Colorado at 2743m suspects everyone who lives at altitude has polyerythrocythemia as more accurately described by Dr. Gustavo Zubieta-Calleja of La Paz, Bolivia at 3625m.)

Only about 2% of the world’s population resides at what is considered “high altitude”. Given the current world population (over 8 billion, 5 million), that is still over 160,100,000 people. The sheer number of people that may be at increased risk of stroke is all the more reason for us to act, and act soon, to get more research done. This is further exemplified by the fact that “cerebrovascular events or stroke is the second leading cause of death worldwide, affecting more than 16 million people each year” (Ortiz-Prado et. al). Guidelines need to be implemented to assist in the diagnosis and treatment of stroke at high altitude, to help differentiate it from related conditions such as HACE, giving patients the standard of care that they need and deserve. While a fascinating topic, stroke seems to be delegated to the sidelines in the mountains, cast aside by culprits such as HAPE, HACE, altitude sickness, and hypoxia. More research, more resources, and more funding need to be funneled into understanding stroke at higher altitudes. Overall, it is clear living at or even exposure to higher altitudes can result in a multitude of neurological symptoms, and that a higher incidence of stroke may yet be one of them.

References

Maryam J. Syed, Ismail A. Khatri, Wasim Alamgir, and Mohammad Wasay. Stroke at Moderate and High Altitude. High Altitude Medicine & Biology.Mar 2022.1-7. http://doi.org.mwu.idm.oclc.org/10.1089/ham.2021.0043

Current World Population – https://www.worldometers.info/world-population/ 

Ortiz-Prado E, Cordovez SP, Vasconez E, Viscor G, Roderick P. Chronic high-altitude exposure and the epidemiology of ischaemic stroke: a systematic review. BMJ Open. 2022;12(4):e051777. Published 2022 Apr 29. doi:10.1136/bmjopen-2021-051777

Gerken, Jacob (MS), Huber, Nathan (MS), Barron, Ileana (MD, MPH-S), Zapata, Isain (PhD). “Influence of Elevation of Stroke and Cardiovascular Outcomes”. Poster presented at a conference in Colorado, in 2022.

Links

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9058702/ https://www-liebertpub-com.mwu.idm.oclc.org/doi/full/10.1089/ham.2021.0043

Born in Salt Lake City, Utah, Piotr Poczwardowski has also lived in Upstate New York, Florida, and Colorado (where he spent the 13 years prior to moving to Glendale for PA school). While attending the University of Denver, he volunteered at a nearby hospital Emergency Department, and also participated in a study abroad program in Italy. After earning a degree in Psychology, he worked as both a Primary Care Medical Scribe and Neurology MA. His main hobbies include skiing, watching movies, hiking, swimming, playing video games, reading, and playing ping pong. Piotr has also volunteered at the Sky Ridge Medical Center Emergency Department and secured a job as a Primary Care Medical Scribe after graduating from the University of Denver in 2018. Piotr is now attending Midwestern University’s PA program in Glendale, AZ.

Acclimation, Altitude Science, Athletic Training, Child Growth & Development, Doc Talk, Exposure, Health, High Altitude, High Altitude Training & Fitness, Medicine, Mountaineering

Going Home to the Mountains Can Be Dangerous: Re-Entry HAPE (High Altitude Pulmonary Edema)

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Louie was excited to get out on the slopes after spending Thanksgiving with family in Vermont. He got tired early and felt his breathing was harder than usual, leaving early to go home and rest. As a competitive skier he thought that was strange. But he was getting over a cold. He could not have imagined that in 24 hours he would be in the emergency room, fighting for his life.

Louie experienced a dangerous condition, set off by altitude, and inflammation from his “cold”, that caused his lungs to fill with fluid.  His oxygen saturation was 54 % instead of the normal 92, he had been vomiting and feeling very weak and short of breath. His blood tests showed dehydration, hypoxemia and acute kidney injury. His chest x-ray looked like a snowstorm. He was transferred to Children’s Hospital in Denver and admitted to the intensive care unit.

The diagnosis of Re-entry HAPE was confirmed by echocardiogram showing increased pressures in his lungs. He improved rapidly with oxygen and low altitude.

Re-entry HAPE is not rare, affecting several Summit County children every year.  Many do not come to medical attention because after their first episode parents carefully monitor their oxygen and have a concentrator available in their home when they return from travel. 

Medical providers may not be aware of this risk, expecting that children living at altitude are acclimatized. (See blog entry on Acclimatization vs. Adaptation, April 17, 2019) Re-entry HAPE seems to occur mostly in children between the ages of 4 and 15. Inflammation, such as a viral respiratory infection, seems to play a role.  Trauma may also predispose a returning resident to Re-entry HAPE, as described in our blog post from February 5, 2018, Trauma related High Altitude Pulmonary Edema

Louie agreed to share his story on our blog to help educate medical personnel and families living in the mountains about this dangerous condition. Further research will help define who is at risk. 

Exposure, Health, High Altitude

Exostosis of the External Auditory Canal – Surfer’s Ear

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You do not have to be a surfer to have surfer’s ear, but what is it exactly?

Not to be confused with swimmer’s ear surfer’s ear or exostosis of the ear auditory canal is when there is the presence of multiple benign boney outgrowths. It is quite common in individuals who have repeated exposure to cold water or wind, which typically ends up being those who surf waves in the pacific.

So now that we know what surfer’s ear is, how can we tell if we have it?

The diagnosis of Surfer’s ear is made by visual exam with an otoscope by a medical provider. Generally, there are no symptoms of Surfer’s ear unless there are multiple bony outgrowths, or the ones present are occluding your ear canal. In those cases, you may experience ear infections as these outgrowths can narrow the ear canal causing water and debris to become trapped and cause an infection. When there is significant occlusion of the ear canal typically 90% or more conductive hearing loss may occur.

What is the treatment for surfer’s ear?

A great preventative tool, to decrease the occurrence of these bony outgrowths is to wear ear protection like ear plugs when you have exposure to cold water or earmuffs when exposed to cold winds. As mentioned above, when there is only a few and/or small boney outgrowths there tends to be no associated symptoms and in those cases no need for treatment. In those, however, that continue to have exposure to cold water/winds, have several boney outgrowths and/or significant occlusion the only definitive treatment is to have those bony outgrowths removed surgically, this is typically done by an Ear, Nose, and Throat specialist.

References

  1. Surfer’s ear. UCI Health Otolaryngology. https://www.ucihealth.org/medical-services/ear-nose-throat-ent/hearing-ear-disorders/surfers-ear. Accessed October 11, 2022.
  2. Weber PC. Etiology of Hearing Loss in Adults. UpToDate. https://www.uptodate.com/contents/etiology-of-hearing-loss-in-adults?search=surfers+ear§ionRank=1&usage_type=default&anchor=H9&source=machineLearning&selectedTitle=1~150&display_rank=1#H9. Published March 15, 2022. Accessed October 11, 2022.
A young woman with chest-length, curly, dark brown hair smiles showing bright white teeth, dressed in a white coat over a black top.

Gabriela Rodriguez Ortega is a second year Physician Assistant student at Red Rocks Community College in Arvada, CO. She grew up in South Florida and received a Bachelor of Science in Biomedical Sciences and Bachelor of Arts in Psychology from the University of South Florida (Go Bulls!). Prior to PA school, she held many positions in the medical field including ENT medical assistant/scribe, pharmacy technician and ER medical scribe. In her free time, she enjoys spending time with family and friends, running, hiking, roller skating and playing guitar.   

Acclimation, Altitude Science, Child Growth & Development, Doc Talk, Exposure, Health, High Altitude, Medicine

HARPE is the New HAPE

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It took ten years for me to convince high altitude experts that children living in the mountains get high altitude pulmonary edema (HAPE) without leaving home. My observations were published in 2017 in the Journal of High Altitude Medicine and Biology,

High-Altitude Pulmonary Edema
in Mountain Community Residents

This week Dr. Jose A Castro-Rodriguez MD PhD ATSF discussed HAPE in children at the 8th World Hypoxia conference in La Paz including the now renamed high altitude resident pulmonary edema (HARPE) in his presentation.

Dr. Castro-Rodriguez emphasized the importance of recognizing the three forms of HAPE, including reentry HAPE when children return to the mountains from vacation, since these can be life threatening.

My work has been cited in articles by pulmonologists Deborah Liptzin and Dunbar Ivy from Children’s Hospital of Colorado and geneticist Christine Eichstaedt and her team at the University of Heidelberg.

At Ebert Family Clinic we give every patient/family a free pulse oximeter. The ability to measure the oxygen saturation of anyone with cough, congestion, or fatigue can facilitate early treatment with oxygen and prevent visits to the emergency room, hospital and intensive care unit.

I recently received first prize for a poster presentation on HARPE at the fall Colorado Medical Society meeting, and second prize for a poster on Trauma and HAPE.

For more information about HAPE, HARPE and Trauma-related HAPE, see previous blog entries.

References

Ebert-Santos C. High-Altitude Pulmonary Edema in Mountain Community Residents. High Alt Med Biol. 2017 Sep;18(3):278-284. doi: 10.1089/ham.2016.0100. Epub 2017 Aug 28. PMID: 28846035.

Giesenhagen AM, Ivy DD, Brinton JT, Meier MR, Weinman JP, Liptzin DR. High Altitude Pulmonary Edema in Children: A Single Referral Center Evaluation. J Pediatr. 2019 Jul;210:106-111. doi: 10.1016/j.jpeds.2019.02.028. Epub 2019 Apr 17. PMID: 31005280; PMCID: PMC6592742.

Liptzin DR, Abman SH, Giesenhagen A, Ivy DD. An Approach to Children with Pulmonary Edema at High Altitude. High Alt Med Biol. 2018 Mar;19(1):91-98. doi: 10.1089/ham.2017.0096. Epub 2018 Feb 22. PMID: 29470103; PMCID: PMC5905943.

Eichstaedt CA, Mairbäurl H, Song J, Benjamin N, Fischer C, Dehnert C, Schommer K, Berger MM, Bärtsch P, Grünig E, Hinderhofer K. Genetic Predisposition to High-Altitude Pulmonary Edema. High Alt Med Biol. 2020 Mar;21(1):28-36. doi: 10.1089/ham.2019.0083. Epub 2020 Jan 23. PMID: 31976756.

Acclimation, Altitude Science, Backpacking, Exposure, Health, High Altitude, High Altitude Training & Fitness, Medicine, Mountaineering, Technology

High-Altitude Pulmonary Edema is not just for tourists

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HAPE can affect long term locals too. There is no specific test to diagnosis HAPE leading to delayed treatment or improper treatment, including death.

HAPE is defined as fluid accumulation in the lungs when an individual spends about 48 hours at elevations of 8,200 feet or higher. This can occur when 1) tourists who are not accumulated to high altitudes appropriately 2) locals who re-enter high altitude after being at lower elevation for a period of time or 3) long term residents who develop an illness.

What are the signs and symptoms you ask? Exhaustion, dyspnea on exertion, productive cough, tachypnea, tachycardia, low oxygen saturation levels, and crackles upon lung assessments are the most common to be seen. These are very generic symptoms and resemble many other diseases, such as pneumonia and asthma, leading to misdiagnosis and improper treatment.

How is HAPE treated?

The answer is simple, oxygen. The body is being deprived of oxygen and is unable to feed our cells. By giving oxygen (either through an artificial source or returning to lower elevation) and allowing the body to rest, the body is able to meet its demand for oxygen and symptoms resolve. If one receives oxygen and symptoms do not improve, there is most likely an underlying cause that is contributing to the symptoms unrelated to HAPE.

A pulse oximeter is the easiest way that one can monitor their oxygen levels at home. This device can be purchased over the counter, relatively inexpensive, and easy to use. By placing the pulse oximeter on one’s finger, the device will read the individual’s oxygen level which should be greater than 90% (when at altitude). The heart rate will also be recorded which tends to be between 60-100 beats per minute when at rest for adults.

References

A new mechanism to prevent pulmonary edema in severe infections. Lung Disease News. (n.d.). Retrieved September 2, 2022, from https://lungdiseasenews.com/2015/01/14/researchers-discover-a-new-mechanism-to-prevent-pulmonary-edema-in-severe-infections/

Bhattarai, A., Acharya, S., Yadav, J. K., & Wilkes, M. (2019). Delayed-onset high altitude pulmonary edema: A case report. Wilderness & Environmental Medicine, 30(1), 90–92. https://doi.org/10.1016/j.wem.2018.11.002

Fixler, K. (2017, October 12). Colorado doctor: Health effects of living in mountains unknown to medical establishment. SummitDaily.com. Retrieved September 2, 2022, from https://www.summitdaily.com/news/summit-county-doctor-makes-a-case-for-high-altitude-disorder-that-affects-even-the-acclimated/

Backcountry, Backpacking, Exposure, Health, High Altitude, High Altitude Training & Fitness, Huts, Medicine, Mountaineering, Naturopathic Medicine, Wildlife

Lost, Stranded, and Hungry in the Mountains of Western Colorado? A Mini Guide to Edible Plants

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From backpacking and camping to skiing and snowboarding, there are plenty of activities outdoors in the Colorado high country. If you find yourself wandering around and lost without food in the mountains, there are several wild plants that you can eat. 

However, before you consume the delectable greens, there are a few precautions to take.

Moose shopping
  • Do not eat any wild plants unless you can positively identify them. There are iOS and Android apps that you can download prior to your hike to help distinguish plants, such as PictureThis and NatureID. 
  • Be aware of environmental factors such as pollution or animal waste. Avoid popular wild animal gathering areas.
  • Make sure you’re not allergic to the plant by rubbing it against your skin and observing for a reaction. If so, do not eat the plant. Before ingesting a large quantity, eat a small amount and check for a reaction. 

It may be difficult to cook if you did not come prepared with a portable stove, pots, and water, which could limit ways to enjoy vegetation. Here is a list of edible plants, how to identify them, where can they be found, and which part you can eat.

Wild plants

Dandelions (Taraxacum officinale): yellow ray florets that spread outward from center with toothy, deep-notched, hairless basal leaves and hollow stems. They can be found everywhere and anywhere. Every part of the dandelion plant is edible including the leaves and roots.

Yellow-green hemispheres bud in a bunch from green stems with pine needle-like leaves.

Pineapple Weed/ Wild Chamomile (Matricaria discoidea): the flower heads are cone-shaped and yellowish-green and do not have petals. Often found near walking paths and roadsides, harvest away from disturbed, polluted areas. If you’re feeling anxious about being lost, pineapple weed promotes  relaxation and sleep and serves as a  digestive aid.

Fireweed (Epilobium angustifolium): vibrant fuchsia flowers. Grows in disturbed areas and near recent burn zones. Eat the leaves when they are young as  adult leaves can stupefy you. Young shoot tips and roots are also edible. 

Wild onions (Allium cernuum): look for pink, lavender to white flowers with a strong scent of onion. They grow in the subalpine terrain and are found on moist hillsides and meadows. Caution: do not confuse with death camas. If it doesn’t smell like an onion and has pink flowers, it is not likely an onion.

Cattails (Typha latifolia or Typha angustifolia): typically 5-10 feet tall. Mature flower stalks resemble the tail of a cat. Grow by creek, river, ponds, and lakes. This whole plant is edible, from the top to the roots. Select from pollution-free areas as it is known to absorb toxins in the surrounding water.

Wild berries:

Wild strawberries (Fragaria virginiana): they are tiny compared to  store-bought. Can be identified by their blue-green leaves; small cluster of white flowers with a yellow center; and slightly hairy, long and slender red stems.

Huckleberries (Vaccinium spp): They grow in the high mountain acidic soil and flourish in the forest grounds underneath small, oval-shaped, pointed leaves. They resemble blueberries and have a distinguishable “crown” structure at the bottom of the berry. They can be red, maroon, dark blue, powder-blue, or purple-blue to almost black, and they range from translucent to opaque.

Deep blue berries stand out against bright red and green, waxy leaves.

Oregon grapes (Mahonia aquifolium): powder-blue berries, resembling juniper berries or blueberries, with spiny leaves similar to hollies that may have reddish tints.

Fun fact: The roots and bark of the plant contain a compound called berberine. Berberine has antimicrobial, antiviral, antifungal, and antibiotic properties.

Mushrooms

Brown whole and halved mushrooms lie on a green table with ridged, sponge-looking caps.

True morels (Morchella spp.): cone-shaped top with lots of deep crevices resembling a sponge. They will be hollow inside. A false morel will have a similar appearance on the outside but will not be hollow on the inside and are toxic. Morels are commonly found at the edge of forested areas where ash, aspen, elm, and oak trees live. Dead trees (forest wildfires) and old apple orchards are prime spots for morels.

Short, stubby mushrooms with white stems and brown camps stand in a row growing over grass.

Porcini (Boletus edulis): brown-capped mushrooms with thick, white stalks. Found at  high elevations of 10,500 and 11,200 ft in  areas with monsoon rains and sustained summer heat.

There are many more edible plants, flowers, berries, and mushrooms in the mountains. These are just 10 that can be easily identifiable and common in the Western Colorado landscapes. I recommend trying out the apps listed above and reading “Wild Edible Plants of Colorado” by Charles W. Kane, which includes 58 plants from various regions, each with details of use and preparation. Hopefully this post made you feel more prepared for your next adventure. 

Resources:

Davis, E., 2022. Fall plant tour: Frisco, CO | Wild Food Girl. [online] Wildfoodgirl.com. Available at: <https://wildfoodgirl.com/2012/eleven-edible-wild-plants-from-frisco-trailhead/> [Accessed 10 July 2022].

McGuire, P., 2022. 8 Delicious Foods to Forage in Colorado | Wild Berries…. [online] Uncovercolorado.com. Available at: <https://www.uncovercolorado.com/foraging-for-food-in-colorado/> [Accessed 10 July2022].

Rmhp.org. 2022. Edible Plants On The Western Slope | RMHP Blog. [online] Available at: <https://www.rmhp.org/blog/2020/march/foraging-for-edible-plants> [Accessed 10 July 2022].

Lifescapecolorado.com. 2022. [online] Available at: <https://lifescapecolorado.com/2014/01/edible-plants-of-colorado/> [Accessed 10 July 2022].

Pfaf.org. 2022. Plant Search Result. [online] Available at: <https://pfaf.org/user/DatabaseSearhResult.aspx> [Accessed 10 July 2022].

Cindy Hinh is a second-year Physician Assistant student at Red Rocks Community College in Arvada, CO. She grew up in southern Louisiana and received her undergraduate degree in Biology from Louisiana State University. Prior to PA school, she was a medical scribe in the emergency department and an urgent care tech. In her free time, she enjoys baking, cooking, going on food adventures, hiking, and spending time with family and friends.

Acclimation, Exposure, Health, High Altitude, High Altitude Training & Fitness

Non-Freezing Cold Injury

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Eighteen-year-old, NorAm skier, NCAA Division I Rugby player, and lover of the outdoors, presents to the clinic complaining of cold, painful hands. She states hands always feel cold, and in cold weather they are extremely painful. Blood tests to rule out vascular disease were normal. What could be the cause of this?

Normally, in cold weather our bodies work to keep essential organs functioning. Skin is not considered essential. When exposed to cold, blood vessels constrict, decreasing blood flow to the skin. Because the metabolic demand of our skin is low, more important organs like our heart and brain need the blood flow. Paradoxically, exposure to cooler temperatures like those below 15 degrees Celsius or 59 degrees Fahrenheit can cause cold-induced vasodilation. This allows blood to flow to the skin to help prevent more serious injury or frostbite. The vasodilation cycles in 5- to 10-minute intervals.

Nonfreezing cold injury (NFCI) occurs when tissues are damaged due to prolonged cooling exposure, but not freezing temperatures. NFCI is due to exposure of the extremities to temperatures around 0 to 15°C or 32 to 59°F, commonly the hands and feet. Current theory is that NFCI is due to a combination of vascular and neural dysfunction. With prolonged vasoconstriction, the skin experiences reduced blood flow with a neurological component influencing the damage as well.

Some patients living in cold environments like the Inuit, Sami people, and Nordic fisherman have a larger cold-induced vasodilation response and more rapid cycling. This is thought to decrease their risk of NFCI. Is it possible that patients who develop NFCI have a smaller and slower cycling of their cold-induced vasodilation? Could this be the issue with our patient with NFCI?  Further research is needed to learn more about NFCI and find better ways to treat it.

What we do know is there are 4 Stages of NFCI:

Stage 1: During the cold exposure – Loss of sensation, numbness, clumsiness. Usually painless unless rewarming is attempted.

Stage 2: Following cold exposure – occurs during and after rewarming. Skin can develop a mottled pale blue-like color, area continues to feel cold and numb, possible swelling. Usually lasts a few hours to several days.

Stage 3: Hyperemia – affected area becomes red and painful. Begins suddenly and lasts for several days to weeks.

Stage 4: Following hyperemia – affected areas appear normal but are hypersensitive to the cold. Areas may remain cold even after short exposure to the cold. This stage can last for weeks to years.

Mountains covered in pine forests reach up past tree line toward a deep blue sky spotted with fluffy white cumulous clouds over two people in bikinis standing on paddle boards reflected with the clouds in the dark water below them.

Outdoor paddle sports like kayaking and canoeing put patients at greatest risk due to the continual exposure to the cold, wet environment. It was thought that in order to have NFCI, one had to be exposed to both cold and wet environments. However, it has been shown that this is not always the case. Like in our patient, exposure to just cold environment can trigger the syndrome. Our 18-year-old patient is an avid skier and spends most of the winter on the mountain. It was also noted that she enjoys paddleboarding and kayaking, which were recognized as triggers for the hand pain. We are unable to determine exactly what caused our patient to develop this syndrome. But we do know it affects their life significantly.

 We choose to live in the mountains because of the things we love. Whether it is hiking, biking, skiing, kayaking, paddleboarding, or the hundreds of other activities offered in this area, we are at risk of NFCI. Currently, there is no good treatment for this syndrome. Prevention is  best. The purpose of this blog is to share information about staying healthy at high altitude. Sharing this information on the stages of NFCI with friends and family will help prevent this painful, debilitating syndrome.

Resources

Nonfreezing cold water (trench foot) and warm water immersion injuries. UpToDate. https://www.uptodate.com/contents/nonfreezing-cold-water-trench-foot-and-warm-water-immersion-injuries/print#:~:text=Nonfreezing%20cold%20injury%20%E2%80%94%20NFCI%20is,to%2059%C2%B0F)%20conditions. Accessed July 14, 2022.

Oakley B, Brown HL, Johnson N, Bainbridge C. Nonfreezing cold injury and cold intolerance in Paddlesport. Wilderness & Environmental Medicine. 2022;33(2):187-196. doi:10.1016/j.wem.2022.03.003

Rachel Cole is a Physician Assistant Student at Red Rocks Community College in Denver, Colorado. She originally grew up in Salt Lake City, Utah, where she learned to love the outdoors. She studied Biology at Western Colorado University in Gunnison, Colorado prior to PA school. She played soccer for the college and fell in love with Colorado and small mountain towns. When she is not studying for school, she enjoys skiing, hiking, backpacking, fishing, waterskiing, canyoneering, and any other activities that get her outside. After graduation she hopes to practice family medicine in a rural community in the mountains.

Acclimation, Altitude Science, Child Growth & Development, Exposure, Health, High Altitude

Kids Living at Altitude are Built Different: How Phenotypic Variations in Pediatric Patients Born at Altitude Help Them Compensate for Their Hypoxic Environment

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One of the phenomena I experienced while caring for pediatric patients in Summit County was the image of a [1] child with an oxygen saturation of 83% who wasn’t in any respiratory distress. This got me thinking: do adaptations in children exposed to chronic hypoxia at altitude prepare them to encounter an episode of acute hypoxia?

It turns out this phenomenon has been studied previously. Children permanently residing at high altitudes exhibit phenotypic variations to help them adapt to their chronically hypoxic environment. According to de Meer, K., et al., for those children living at altitudes greater than 3000m above sea level since gametogenesis, the opportunities for phenotypic plasticity are particularly excellent.

These changes in phenotypic expression have led to both theorized and proven physiologic differences in oxygen uptake, transport, systemic circulation, and consumption, allowing them to overcome the effects of chronic high-altitude hypoxia.

The lower partial pressure of oxygen causes high-altitude hypoxia to those who are visiting from lower altitudes. With less oxygen in the air, increased respiratory effort would be required to maintain the same oxygen levels as those children living at sea level. However, children living at altitude have physiologic increases in ventilation, lung compliance, and pulmonary diffusion, which help negate the need for augmented respiratory effort.

To conserve respiratory rate, increases in lung compliance and tidal volume have been observed in children living at altitude. In one study by Mortola, J. P., et al., lung compliance and tidal volume remained increased even while participants were on 100% supplemental oxygen.      This suggests that this is a permanent physiological adaptation in kids living at altitude.2

Additionally, children living at altitude are more efficient at delivering oxygen to their tissues. An increase in pulmonary diffusion capacity facilitates this improved efficiency. Pulmonary diffusion capacity is determined by the surface area available for diffusion. Assuming all other anatomic variables are the same in highlanders and lowlanders[2] , this increased capacity can only be explained by an increase in the number and size of alveoli.1 To study this possibility, researchers compared the lung volumes and chest dimensions of children exposed to chronic hypoxia at altitude since birth to those of children living at sea level and found that lung volumes and chest dimensions of children residing at altitude indeed were greater.

Despite this opportunity for increased oxygen uptake by the lungs of children living at altitude, the partial pressure of oxygen in their blood is still substantially lower. This decrease in arterial blood oxygen concentration that is associated with hypoxia encourages the kidneys to release erythropoietin, which subsequently stimulates the production of erythrocytes contributing to an increased erythrocyte and hemoglobin concentration in children living at altitude. Elevated hemoglobin concentration leads to a relative increase in arterial oxygen saturation, which compensates for the lower availability of oxygen at altitude.1

Despite the witnessed phenomenon of the ability of children living at altitude to adapt to acute hypoxia, it is still debated whether chronic hypoxemia in this population results in decreased oxygen consumption. New research has concluded that previously observed decreases in oxygen metabolism in newborns at altitude are reactions to acute stress and hypoxia and should not be considered an effect of chronic exposure to hypoxia.1 In other words, the ability of children living at altitude to decrease ventilation during an episode of acute hypoxia is due to a decrease in tissue metabolism only during that event of respiratory stress.

Like most things in life, these advantages do not come without consequences. Humans exposed to chronic hypoxia are prone to pulmonary hypertension; in fact, phenotypic, physiological changes in tidal volume and lung diffusion that improve oxygen uptake contribute to pulmonary hypertension. However, unlike children who develop pulmonary hypertension unrelated to altitude, highland children often present with a less severe clinical picture and fewer irreversible complications.1

Children born and residing at altitude offer a window into a world of medical phenomena that are little understood. The more we know about the physiological differences in this population, the better we can serve them as clinicians.

References

  1. de Meer, K., et al. “Physical Adaptation of Children to Life at High Altitude.” European Journal of Pediatrics, vol. 154, no. 4, Apr. 1995, pp. 263–72. Springer Link, https://doi.org/10.1007/BF01957359.
  2. Mortola, J. P., et al. “Compliance of the Respiratory System in Infants Born at High Altitude.” The American Review of Respiratory Disease, vol. 142, no. 1, July 1990, pp. 43–48. PubMed, https://doi.org/10.1164/ajrccm/142.1.43.

Lauren Thompson is a second-year Physician Assistant Student at Drexel University in Philadelphia. She is here all the way from sunny sea level, Florida, where she got her degree in Psychology with a minor in Biology from Florida State University. She is currently completing her clinical rotation, which has taken her all over the country with her feline and canine companions, Duke and Remi. Before PA school, Lauren worked as a Certified Nursing Assistant at a local hospital and a Medical Assistant at a pediatric specialty clinic. Outside of medicine, Lauren enjoys traveling, spending time with her animals, singing karaoke, playing disc golf, and taking in all of what mother nature has to offer, whether it’s hiking, skiing, diving, or enjoying the beach.

Backcountry, Backpacking, Exposure, High Altitude, High Altitude Training & Fitness, Mountaineering

After 21 Years of Hiking at Altitude I Had to Call Rescue

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Another Lesson on High Altitude Health and Safety

Wild animals, storms, avalanches, cold, high altitude pulmonary edema or cerebral edema, falls, fires and injuries are the most common dangers in the mountains. I’ve climbed 19 different mountains in Colorado over 14,000′, and some of them more than once, making for 28 successful ascents. But I called Summit County Search and Rescue Saturday for something I was not expecting: deep wet snow that trapped me less than 2 miles from the trailhead.

A colorful map of lines in red, green and white depicting trails through various mountain terrain.
Summit County trail map

It was a bright, warm day — I had even left my hand warmers at home. My plan was to hike from Miners Creek trailhead in Frisco to Gold Hill Trailhead north of Breckenridge which is about a 6- or 7-mile trip one way. I had hiked from both ends in previous weeks and saw the turn-off had snow and no tracks. I attached my snowshoes to my backpack with plans to turn up towards Gold Hill if there were tracks, and there were.

After 4 miles I was out of the forest on top with gorgeous 360˚ views of mountains. I no longer saw the trail markers or tracks so set out across the open space with my snowshoes sinking into the snow every 10 to 20 feet. The trail maps and GPS on my phone were sketchy, only showing I was very near the Colorado Trail. I turned down a logging road to get out of the wind thinking the snow would be packed. I could see several open areas that I thought would take me to the familiar trails to Gold Hill.

After an hour sinking into deep snow I noticed I had only one snowshoe. I backtracked 100 feet following the tracks to find it, dug at several spots where I had sunk the deepest but never found it. I went back towards the Colorado Trail but could not progress, having to dig my boot out of deep snow several times.  I tried to backtrack in my footsteps but couldn’t get far. I had now covered a mile in an hour and a half, my phone showing I was only 48 minutes from the Gold Hill trailhead.

So I called 911, thinking they could drive a snowmobile up to get me.  Bad news: the vehicle would just sink the same way I was. The 911 operator knew me and the Summit County Search & Rescue mission coordinator Mark Svenson was in touch several times as I waited from 3:17 until about 6 pm when the crew arrived with skis and extra snowshoes. My Blue Heeler Isa and I stayed within one foot of a small pine tree where we found firm footing after rolling through the deep, soft snow. Luckily the sun kept us warm until 5 pm, and I had food and water. My gloves and boots were soaked so my feet were very cold and I tried to keep Isa lying over my legs or feet.  I had a plastic rain shield extension that I could pull out and sit on in a pocket of the backpack that one of my students had gifted me.

The rescuers had water, snacks, dry socks, dry gloves, gators and snowshoes. They had packed down the trail but there were still times we post-holed on the way down. We arrived at the rescue vehicle as darkness fell. Special Operations Sheriff SJ Hamit waited with Mark and other SCSR staff to welcome us. One of the rescuers told me how happy he was that I was still smiling when they arrived!

Summit County Search & Rescue team, Sheriff Hamit on the left, Dr. Chris far right.

What did I learn? Stay out of deep, wet snow even if it means going back the long way. Bring extra socks and gloves. Buy gators.

I was not afraid because I knew they were coming before dark. I do feel exhilarated that I was able to do such a challenging hike without any pain or blisters, that my knees were strong enough to extract my feet from the deep snow so many times, and that Isa was with me to warn if any animals were near and announce when the rescuers arrived.

Christine Ebert-Santos, MD, MPS is the founding physician and president of Ebert Family Clinic in Frisco, Colorado, where she leads high altitude research in addition to running a full-time family practice. Isa is a two-year-old blue heeler and Dr. Chris’s familiar and guardian angel.

Altitude Science, Exposure, Health, High Altitude

A Hike a Day May Keep the Cardiologist Away

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Cardiovascular disease is one of the leading causes of death worldwide, with approximately 17.9 million people succumbing to the disease annually (World Health Organization, 2021). In the United States, there is an estimated 18.2 million Americans (20 years and older) with coronary artery disease. Of those, an estimated 655,000 Americans die annually from heart disease. Approximately 805,000 experience myocardial infarction (i.e., heart attack); 605,000 of these are first time heart attacks, and the other 200,000 have experienced at least one in their lifetime (Centers for Disease Control, 2020). Prevention and management of myocardial infarctions is constantly evolving, and new innovations are being developed to minimize the long-term, chronic consequences one may deal with. Interestingly, it is possible that life at higher altitudes, such as in the Rocky Mountains, may provide a natural edge over life at sea level. For example, Summit County, Colorado (avg elevation ~11,113 ft) has a life expectancy of 86.83 years (Stebbins, 2019). On the contrary, Lauderdale County, Mississippi (elevation 668 ft) has a life expectancy of 75.2 years (U.S.News, 2021). When looking at data regarding heart attack deaths, Summit County experiences 7.2 per 100,000 and Lauderdale County has 334.1 per 100,000 (Centers for Disease Control, 2017-2019).

Myocardial infarction is defined by cardiac muscle death that results from prolonged ischemia. The ischemia is typically the result of an atherosclerotic plaque that ruptures and occludes an artery supplying an area of heart muscle. This leads to an imbalance between the oxygen supply and demand in the affected tissue. Additional swelling ensues, occluding microcirculation, which results in more regional ischemia (Montecucco, Carbone, & Schindler, 2016). In addition to the lack of oxygen, cardiac cells overload with calcium, which causes excess contraction, cytoskeleton digestion, excess reactive oxygen species (ROS) formation, DNA fragmentation, and the release of cytochrome C from mitochondria, which signals cellular death (Heusch & Gersh, 2017).

How might altitude play a protective role in such a complicated process? There are many hypotheses out there, and some interesting findings have been discovered in animal models. Mentioned earlier, ROS fragment the DNA within cardiac cells, which is a trigger for cellular death. With the DNA damaged, cellular function ceases. ROS exposure is a normal part of life; they result from the oxygen we breath, which form free radicals (lone oxygen atoms), the pollution in the air, and the alcohol one may consume. Surprisingly, there is a reduction of ROS formation when someone is at a high enough altitude. This leads to the cardiac cell’s ability to form new, healthy cells. This suggests that ROS are like the breaks to a car and reduces the cell’s ability to move forward in the process of cell division. By taking the breaks off, it may be possible to regenerate healthy, functional tissue (Nakada, et al., 2017).

Another issue of myocardial infarction is the process of remodeling and scar tissue formation. Depending on the extent of the damage, remodeling can be detrimental and compromise the heart’s ability to pump blood efficiently. The inflammation that results signals neutrophils to the area to form scar tissue to try and repair the damage. Neutrophils also work to prevent adverse remodeling. The goal in managing heart attacks is to minimize any sort of damage that may result, but if we are too aggressive in this process, we can cause the formation of excess ROS. These ROS play a role in prolonging the lifespan of these neutrophils, allowing them to keep working. If we do not get timely resolution of the neutrophil remodeling, then healing may not be optimized (Montecucco, Carbone, & Schindler, 2016).

One study in rats explored how the heart remodels when exposed to intermittent hypoxia. Over the course of this study, rats were gradually exposed to higher simulated altitudes, and returned to baseline elevations for periods of time. The highest elevation they were exposed to was 8000 m, or the summit of Mt. Everest. They discovered that both right and left ventricles did remodel over the course of the experiment, but the left ventricle experienced significant remodeling only at the highest altitude. They also discovered that the functionality of the left ventricle was maintained. The remodeling was explained by reoxygenation that occurred at normal elevations, which resumed the production of ROS. This mechanism was absent at altitude. There are rare adverse effects of living at high altitude, which include stunted body growth, erythrocythemia (excess red blood cell formation), pulmonary hypertension, and myocardial fibrosis (Papoušek, Sedmera, Neckár, Oštádal, & Kolár, 2020).

It is exciting to explore some of the possible benefits of being and living in higher elevations. Going forward, it will be important to see if there are clinical applications, and if these applications can be administered safely and efficiently. Just like scuba divers being treated for the bends in hyperbaric chambers, what if we can develop a hypobaric chamber for those who experienced a recent heart attack? Is it possible to minimize damage by reducing the amount of oxygen entering the body, and how long would one have to be exposed to such treatment? These are very important questions that need further investigation. For now, the best course of action is to eat healthy, stop smoking, and go for a hike. If you happen to be hiking in Colorado, it may help keep the cardiologist away.

References

Centers for Disease Control. (2017-2019). Interactive Atlas of Heart Disease and Stroke. Retrieved from Centers for Disease Control and Prevention: https://nccd.cdc.gov/DHDSPAtlas/reports.aspx?geographyType=county&state=CO&themeId=8&filterIds=9,2,3,4,7&filterOptions=1,1,1,1,1#report

Centers for Disease Control. (2020, September 8). Heart Disease Facts. Retrieved from Centers for Disease Control and Prevention: https://www.cdc.gov/heartdisease/facts.htm

Heusch, G., & Gersh, B. J. (2017). The pathophysiology of acute myocardial infarction and strategies of protection beyond reperfusion: a continual challenge. European Society of Cardiology, 774-784.

Montecucco, F., Carbone, F., & Schindler, T. H. (2016). Pathophysiology of ST-segment elevation myocardial infarction: novel mechanisms and treatments. European Society of Cardiology, 1268-1283.

Nakada, Y., Canseco, D. C., Thet, S., Abdisalaam, S., Asaithamby, A., Santos, C. X., . . . Schiattarella. (2017). Hypoxia induces heart regeneration in adult mice. Nature, 222-226.

Papoušek, F., Sedmera, D., Neckár, J., Oštádal, B., & Kolár, F. (2020). Left ventricular function and remodelling in rats exposed stepwise up to extreme chronic intermittent hypoxia. Respiratory Physiology and Neurobiology.

Stebbins, S. (2019, September 6). 50 counties with high life expectancies: Does yours make the list? Retrieved from USA Today: https://www.usatoday.com/story/money/2019/09/06/the-50-counties-where-people-live-the-longest/40072465/

U.S.News. (2021). Overview of Lauderdale County, MS. Retrieved from U.S.News: https://www.usnews.com/news/healthiest-communities/mississippi/lauderdale-county

World Health Organization. (2021, June 11). Cardiovascular Diseases (CVDs). Retrieved from World Health Organization: https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)

Tyler Cole is a second year Physician Assistant student at Midwestern University in Glendale, Arizona. He was born and raised in Glendale, and went to The University of Arizona in Tucson, where he earned his bachelor’s in Physiology and Biochemistry in 2013. From there, he went on to serve the city of Tucson as an Emergency Medical Technician for six years. He was also an EMT instructor at Pima Community College for three years. Outside of medicine, Tyler enjoys watching hockey, fishing, traveling, and spending time with his dog, Louie.