Category Archives: Exposure

Acclimation, Altitude Science, Exposure, Health, High Altitude, Technology

From Mountains to Mars: Why High-Altitude Research Matters for Mars Missions

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Thin Air

You step out of your car at roughly 9,000 feet in Frisco, Colorado, and the first thing you notice isn’t the mountain views –it’s your breath. It comes faster, deeper, almost as if your body knows something you don’t: the air pressure here is lower and each breath delivers ~28% fewer oxygen molecules than at sea level1. This “thin air” triggers the same hypoxic (low-oxygen) stress that Mars settlers will face, where every habitat and spacesuit must carefully control both pressure and oxygen1,2,7,8. On Mars, the atmospheric pressure is less than 1% of that on Earth.

Acclimatization

On your first hike, your heart pounds harder than usual. That’s your body’s rapid response: breathing quickens, heart rate rises, and oxygen delivery ramps up to keep the entire body going1,2,4. Within 24-48 hours, your kidneys release erythropoietin (EPO), signaling the bone marrow to make more red blood cells1,3. This raises hemoglobin levels, enhancing oxygen transport. Over the following weeks, blood volume and hemoglobin continue to rise1,2,4. This is acclimatization –which varies between individuals, an important consideration when selecting crew for long-duration Mars missions.

Sleep and Oxygen

At night, breathing becomes fragile. Many people develop “periodic breathing” –brief pauses that fragment sleep. Summit County residents often experience oxygen dips into the high 80% –lower than the ~90% seen in Denver; and far below the typical 96-98% at sea level1. These dips have real implications: hypoxia combined with sleep disruption can affect mood, stress, and cognitive performance, as seen in Antarctic “winter overs,” where low oxygen and isolation caused up to 20% drop in certain cognitive task speeds and increased mood disturbances. Altitude sleep data are useful for researchers to determine extra nighttime buffers and habitat controls. Predicting and mitigating these person-specific patterns is key for astronaut safety and performance4,5.

From Frisco to the Final Frontier

Frisco, Colorado is not just known for its scenic views. This mountain town serves as a “living laboratory”, allowing researchers to track oxygen saturation, breathing, heart rate, sleep, and exercise tolerance in residents and visitors. These insights can help engineers determine how much oxygen a Mars habitat should provide, and how quickly conditions can safely change after landing1,2,7,8. NASA spacecraft air pressures currently range from 8.2 – 14.7 psi, with oxygen comprising 21-32% of that air; parameters informed in part by high-altitude research7,8. At the 7th Chronic Hypoxia Symposium in La Paz, Bolivia at 12,000 feet elevation (3,640 m) the use of insights from high altitude populations to enable the exploration of Space was discussed. The sponsor and organizers were Drs. Gustavo Zubieta-Calleja and his daughter Natalia Zubieta De Urioste who run the Institute of High Altitude Pulmonology and Pathology there. Presenters and attendees came from 16 countries covering topics ranging from molecular biology to genetics.
A presentation on “BioSpaceForming”  identifies chronic hypoxia as a “fundamental tool” that “gives humans and other species an advantage on earth and beyond.” Dr Zubieta explained that the space station is engineered to have the barometric pressure (760 mmHg) and oxygen content of sea level. When the astronauts change into their space suits to work outside the ship they experience a pressure drop of over 200 mm Hg in a laborious process of donning the suit. Seeing that millions of inhabitants are healthy at 486 mm HG in Bolivia, he advocates that maintaining lower pressures and lower oxygen levels in the space station would be economical and promote the health of the astronauts. Several altitude scientists see this as a future that “uncouples biology and physics.

(Photo of Dr Gustavo in front of space slide)

Modeling Mars Conditions

Researchers combine data from high-altitude locations, Antarctic stations, Mars-analog habitats like HI-SEAS in Hawaii to build predictive models. These models provide guidelines for when oxygen supplementation or workload adjustments are needed to optimize safety while completing tasks 4-6,9. They also help develop “operations playbooks” for simulating life on Mars10; set habitat air pressure and oxygen guidelines7,8; define spacesuit safety limits4,6,11; and better understand how the human body responds to spaceflight and space living2,5,9,12,13. For example, extravehicular activity (EVA) suits –spacesuits used for work outside the spacecraft –typically operate at ~4.3 psi with 100% oxygen. While this allows astronauts to breathe in low-pressure environments, prolonged use can lead to overheating, dehydration, and higher risk of injuries11.

The gravitational pull is 38% of that on Earth. Solar and the more dangerous Galactic Cosmic Radiation of Alpha particles from distant supernovae is hundreds of times greater than on Earth, due to the lack of a magnetic field or protective atmosphere. A breeze on Mars could barely move a blade of grass. Global dust storms occur every few years and last months, devastating the surface.

At the 9th  Chronic Hypoxia and First International Space Physiology Symposium in La Paz, Bolivia in 2025 Dr. Akbar Hussain presented his Craterhab design for accommodations in austere high altitude environments and eventually on Mars.

(PHOTO akbar in front of slide with craterhub) 

Astronauts could be acclimatized before embarking on the long journey to distant space in facilities located at 5,000 meters near mines in the Andes.

(Photo of Dr Gustavo in front of space slide)

Limitations

Most high-altitude studies are conducted over weeks to months, while Mars missions could last years and require hundreds of participants to have the skills to be self-sustaining. Due to planetary rotations, travel to Mars is only feasible once every 26 months. Messages from Mars take 7 to 45 minutes to arrive on Earth. Individual differences in acclimatization, long-term cognitive effects, and combined stressors like radiation or microgravity are not fully captured. Longer-duration studies at high-altitudes, combined with simulated Martian habitats and spacesuit trials, are needed to refine safety parameters.

Conclusion

High-altitude research gives scientists a window into human maladaptive and adaptive responses to low-oxygen, low-pressure conditions on Earth, and is directly relevant to anticipating health risks and necessary countermeasures for human habitation on Mars.

References

  1. 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.
  2. Le Roy B, Martin-Krumm C, Pinol N, Dutheil F, Trousselard M. Human challenges to adaptation to extreme professional environments: A systematic review. Neurosci Biobehav Rev. 2023;146:105054. doi:10.1016/j.neubiorev.2023.105054.
  3. Roach RC, Hackett PH. Frontiers of hypoxia research: acute mountain sickness. J Exp Biol. 2001 Sep;204(Pt 18):3161-70. doi: 10.1242/jeb.204.18.3161. PMID: 11581330.
  4. Mairesse O, MacDonald-Nethercott E, Neu D, et al. Preparing for Mars: Human sleep and performance during a 13-month stay in Antarctica. Sleep. 2019;42(1). doi:10.1093/sleep/zsy206.
  5. Pagel JI, Choukèr A. Effects of isolation and confinement on humans—Implications for manned space explorations. J Appl Physiol (1985). 2016;120(12):1449-1457. doi:10.1152/japplphysiol.00928.2015.
  6. Dunn Rosenberg J, Jannasch A, Binsted K, Landry S. Biobehavioral and psychosocial stress changes during three 8–12 month spaceflight analog missions with Mars-like conditions of isolation and confinement. Front Physiol. 2022;13:898841. doi:10.3389/fphys.2022.898841.
  7. Waligora JM, Horrigan DJ, Nicogossian A. The physiology of spacecraft and space suit atmosphere selection. Acta Astronaut. 1991;23:171-177. doi:10.1016/0094-5765(91)90116-M.
  8. Morgenthaler GW, Fester DA, Cooley CG. An assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations. Acta Astronaut. 1994;32(1):39-49. doi:10.1016/0094-5765(94)90146-5.
  9. Sarma MS, Shelhamer M. The human biology of spaceflight. Am J Hum Biol. 2024;36(3):e24048. doi:10.1002/ajhb.24048.
  10. Lim DSS, Abercromby AFJ, Kobs Nawotniak SE, et al. The BASALT research program: Designing and developing mission elements in support of human scientific exploration of Mars. Astrobiology. 2019;19(3):245-259. doi:10.1089/ast.2018.1869.
  11. Stirling L, Arezes P, Anderson A. Implications of space suit injury risk for developing computational performance models. Aerosp Med Hum Perform. 2019;90(6):553-565. doi:10.3357/AMHP.5221.2019.
  12. Cassaro A, Pacelli C, Aureli L, et al. Antarctica as a reservoir of planetary analogue environments. Extremophiles. 2021;25(5-6):437-458. doi:10.1007/s00792-021-01245-w.
  13. Fairén AG, Davila AF, Lim D, et al. Astrobiology through the ages of Mars: The study of terrestrial analogues to understand the habitability of Mars. Astrobiology. 2010;10(8):821-843. doi:10.1089/ast.2009.0440.
  14. Akbar Hussain M, Ayaz Hussain M, Mehdi Hussain M, Fatima R, Carretero R, eds. Craterhab Technology: Adapting Martian Habitat Systems to Combat Chronic Hypoxia in High-Altitude Mining in the Andes – A White Paper. Mareekh Dynamics. Published June 3, 2024. Accessed August 15, 2025. https://www.mareekh.com/post/craterhab-technology-adapting-martian-habitat-systems-to-combat-chronic-hypoxia-in-high-altitude-mi
Backcountry, Backpacking, Exposure, Health, High Altitude, Huts, Mountaineering, Summit Huts

Lightning Strikes in Colorado

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My love for hiking developed during my childhood explorations of the breathtaking landscapes of the Sierra Nevada. As I ventured into the rugged mountains and hiked along scenic trails, I couldn’t help but feel a deep connection with nature. However, my passion for hiking was not without its moments of caution. On several occasions, I witnessed the awe-inspiring yet intimidating power of lightning storms dancing across the vast mountain skies. These encounters instilled in me a profound curiosity about the risks associated with lightning strikes in high-altitude regions.

When I moved to Colorado for PA school, my awareness of the dangers posed by lightning strikes grew even stronger. The dramatic topography and frequent thunderstorms in Colorado amplify the risk for individuals exploring high-altitude areas. It was during my last clinical rotation at a burn unit that I had the opportunity to care for several patients who had been struck by lightning. Witnessing the effects firsthand fueled my determination to educate the public about the actionable steps they can take to stay safe during lightning storms.

Lightning strikes

​Lightning possesses an immense amount of energy, with a voltage of over 10 million volts (in comparison, most car batteries measure 12.6 V).1 Additionally, a lightning bolt reaches incredibly high temperatures, reportedly up to 30,000 Kelvin (53540.33 F).1 Lightning injuries occur in different ways, including as direct strikes, side splash, contact injuries, or ground current. 

Direct strikes are uncommon, accounting for only 5% of cases, and happen when a person is directly struck by lightning.2

Contact injuries occur when a person touches an object that is struck by lightning. 2

Side splash injuries occur when the current jumps or “splashes” from a nearby object and then follows the path of least resistance to reach the individual. These injuries make up about 1/3 of all lightning related injuries. 2

Ground current is the most prevalent cause of injury, accounting for half of all cases, and occurs when lightning strikes an object or the ground near a person and subsequently travels through the ground to reach the individual. 2

In Colorado, an average of 500,000 lightning flashes hit the ground each year. Based on data since 1980, lightning causes 2 fatalities and 12 injuries per year throughout the state.3According to data since 1980, lightning causes an average of 2 fatalities and 12 injuries annually throughout the state. 3 Colorado ranked third in the United States for the number of lightning fatalities between 2005 and 2014, as depicted in Figure 1.

Fig. 1. Lightning fatalities by state. 3

The high number of injuries attributed to lightning in Colorado can be influenced by several factors. One of these factors is the easy access to high elevation terrain, such as 14ers (mountains with a peak elevation of at least 14,000 feet). This accessibility allows inexperienced outdoor enthusiasts to venture into potentially dangerous situations due to their lack of knowledge and preparation.

For instance, individuals who are not familiar with summer weather patterns may embark on a hike above the tree line late in the day, underestimating the risk of a storm forming. This lack of understanding puts them in an exposed and perilous position should adverse weather conditions arise.

Even with thorough preparation and extensive knowledge of weather patterns, it is still possible to find oneself in a situation where you have to weather a storm. Given that a significant proportion of Colorado’s hiking trails are located above the tree line, where appropriate shelter is sparse, hikers are more susceptible to lightning strikes in these exposed areas. 

Pathophysiology of Lightning Strike Injuries

The overall ratio of lightning injuries to deaths is 10:1 and there is a 90% chance of sequelae in survivors.4 The primary mechanism of injury in lightning strikes is the passage of electrical current through the body. The high voltage and current can cause tissue damage through several mechanisms, including thermal injury, electrical burns, and mechanical disruption of tissues. The severity of the injury depends on factors such as the voltage and current of the lightning bolt, the duration of contact, and the pathway the current takes through the body.

Lightning strikes can cause various types of injuries, with cardiac and respiratory arrest being the most common fatal complications.5 The path of least resistance determines the flow of electricity through different organs in the body, with nerves being the most conductive, followed by blood, muscles, skin, fat, and bone. 5 When lightning strikes, the electrical surge can induce cardiac arrest and cessation of breathing by affecting the medullary respiratory center. As a result, most patients initially present with asystole and may progress to different types of arrhythmias, commonly ventricular fibrillation. 5

Interestingly, there have been case reports documenting successful resuscitation of lightning strike victims who were initially apneic and pulseless for as long as 15 to 30 minutes. 5This has led to the recommendation that in the immediate aftermath of a lightning strike, individuals who appear to be dead should be prioritized for treatment.

Superficial skin burns are experienced by around 90% of lightning strike victims, but deep burns are less common, occurring in less than 5% of cases. A characteristic skin manifestation of a lightning strike is the Lichtenberg figure, which is considered pathognomonic. Neurological symptoms can also occur, including keraunoparalysis, which is a transient paralysis affecting the lower limbs more than the upper limbs. This paralysis is often accompanied by sensory loss, paleness, vasoconstriction, and hypertension, and is thought to result from overstimulation of the autonomic nervous system, leading to vascular spasm. In most cases, this paralysis resolves within several hours, but in some instances, it may last up to 24 hours or cause permanent neurological damage. 5

Additionally, it is common for lightning strike victims to have a perforated tympanic membrane (eardrum) or develop cataracts immediately following the incident. These injuries to the ear and eyes are associated with the intense energy of the lightning discharge. 6

What can hikers do to stay safe?

Preparation

Monitor weather forecasts: Stay updated on weather conditions before engaging in outdoor activities, especially in areas prone to thunderstorms. Pay attention to thunderstorm warnings or watches issued by local authorities. Having a mobile or handheld NOAA Weather Radio All-Hazards (NWR) can also be helpful as it can transmit life-saving weather information at a moment’s notice. 

In Colorado most thunderstorms develop after 11 am, so it is best to plan your trip so that you are descending by late morning.7 Fig. 2 shows number of lightning fatalities by time of day in Colorado between 1980 and 2020. The vast majority take place after the 11 am threshold.

Fig. 2  Lightning fatalities in Colorado by time of day3

What to Do If Caught in a Storm

If you can hear thunder, you are close enough to be struck by lightning. Lightning can strike up to 25 miles away from the storm. 7 Once you hear thunder, if possible quickly move to a sturdy shelter (substantial building with electricity or plumbing or an enclosed, metal-topped vehicle with windows up). Avoid small shelters, such as picnic pavilions, tents, or sheds. Stay sheltered until at least 30 minutes after you hear the last clap of thunder.

Fig 3. Areas to avoid when sheltering from lightning.

If you are outdoors and cannot reach a suitable shelter, avoid open areas, hilltops, and high places that are more exposed to lightning strikes. Seek lower ground and stay away from tall objects, such as trees, poles, or metal structures. Bodies of water, including lakes, rivers, pools, and even wet ground, are conductive and increase the risk of a lightning strike. Move away from these areas during thunderstorms. Separate group members by at least 20 ft as lightning can jump up to 15 feet between objects.

​If a strike is eminent (static electricity causes hair or skin to stand on end, a smell of ozone is detected, a crackling sound is heard nearby), the current recommendation is to assume “lightning position”, pictured in Fig. 4.

Fig. 4. Lightning position8

To potentially reduce the risk of ground current injury from an imminent lightning strike, another strategy is to insulate oneself from the ground. This can be done by sitting on a pack or a rolled foam sleeping pad. However, it’s important to note that this and the lightning position should be considered a strategy of last resort and not relied upon as the primary means of prevention. Maintaining this position for an extended period can be challenging, and it’s crucial to prioritize seeking proper shelter and following established lightning safety guidelines to minimize the overall risk of injury. 5

Case Study

25 YO F presents to the Burn Unit as a transfer from Cheyenne Regional Medical Center s/p lighting strike. Patient (pt) was caught in a thunderstorm on a hike and sheltered under a tall tree. Suddenly, she felt like she was being lifted up into the air and then dropped. Pt had a brief (<5 sec) loss of consciousness (LOC). When she woke up, she was completely numb and couldn’t move any of her extremities. Witness (friend) states the lightning splashed from the tree to the pt. Pt denies hitting her head with the fall. She denies taking blood thinners. She has no past medical history (PMHx) or past surgical history (PSHx).

Physical exam 

Neuro: AOX4, No CN deficit on exam, LE paralysis resolved, LE paresthesia improving but still present

HEENT: L ruptured tympanic membrane, hearing loss on L side

CV: RRR

MSK: Soft compartments diffusely

Skin: Lichtenberg figures on bilateral LE 

Fig. 6. Lichtenberg figure on LLE

V/S: BP: 128/92, HR: 96, RR:18, SPO2: 98%, Temp 98.1F. 

CBC, CMP, troponin were all WNL. Serum hCG negative. CK mildly elevated (222) 

EKG showed NSR.

CXR, CT brain, and c-spine neg for acute injury

She was admitted to the UC Health burn center for observation with tele. Her lab work and vitals remained stable throughout her hospitalization. She was evaluated by the trauma team with a negative trauma work up. The day of discharge, she was tolerating a regular diet, ambulating and sating well on room air. She was deemed appropriate for discharge home without patient audiology and ophthalmology follow up. 

References

1. US Department of Commerce N. Understanding lightning science. National Weather Service. April 16, 2018. Accessed July 8, 2023. https://www.weather.gov/safety/lightning-science-overview. 

2. Cooper MA, Holle RL. Mechanisms of lightning injury should affect lightning safety messages. 21st International Lightning Detection Conference. April 19-20, 2010; Orlando, FL. 

3. US Department of Commerce N. Colorado Lightning statistics as compared to other states. National Weather Service. March 4, 2020. Accessed July 7, 2023.https://www.weather.gov/pub/Colorado_ltg_ranking. 

4. US Department of Commerce N. How dangerous is lightning? National Weather Service. March 12, 2019. Accessed July 8, 2023. https://www.weather.gov/safety/lightning-odds. 

5. Chris Davis, MD; Anna Engeln, MD; Eric L. Johnson, MD; Scott E. McIntosh, MD, MPH; Ken Zafren, MD; Arthur A. Islas, MD, MPH; Christopher McStay, MD; William R. Smith, MD; Tracy Cushing, MD, MPH. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Lightning Injuries: 2014 Update. WILDERNESS & ENVIRONMENTAL MEDICINE. 2014; 25, S86–S95 

6. Flaherty G, Daly J. When lightning strikes: reducing the risk of injury to high-altitude trekkers during thunderstorms. Academic.oup.com. Accessed July 8, 2023. https://academic.oup.com/jtm/article/23/1/tav007/2635599. 

7. NWS Colorado Offices – Boulder G. Colorado Lightning Awareness Week june 19-25, 2022. ArcGIS StoryMaps. June 25, 2022. Accessed July 8, 2023. https://storymaps.arcgis.com/stories/11d021f1b800429a869ead2dc32c0f96. 

8. McKay B and K. How to survive A lightning strike: An illustrated guide. The Art of Manliness. April 25, 2022. Accessed July 8, 2023. https://www.artofmanliness.com/skills/outdoor-survival/how-to-survive-a-lightning-strike-an-illustrated-guide/. 

A woman with long, light brown hair over her shoulders wearing a blue, sleeveless shirt with red details smiles with blue eyes.

Sophia Ruef is a Physician Assistant student at Red Rocks Community College in Arvada, CO. She grew up on the central coast of California and earned her Bachelor of Science degree inBiology with a concentration in anatomy and physiology from Cal Poly San Luis Obispo. She worked as an EMT and a tech in the Bay Area after her undergraduate education. In her free time, she enjoys hiking, backpacking, canyoneering, and spending time with family and friends.

Acclimation, Altitude Science, Diabetes, Exposure, Genetics, Health, High Altitude

Living High and Testing Higher: Can Living at High Altitudes Skew Diagnostic Diabetes Tests? 

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by Hailey Garin PA-S

Diabetes is very prevalent in our society, with around 11% of the population in the United States diagnosed with this disease2. A key diagnostic test used in healthcare is the hemoglobin A1c (HbA1c) blood test. This blood test measures an individual’s average blood sugar over a 3-month period. A value of less than 5.7% is normal, 5.7%-6.4% is pre-diabetic range, and 6.5% and greater is a diagnosis of diabetes1. There are other blood tests that are used in the diagnoses of diabetes including fasting plasma glucose (FPG) and 2-hour postprandial glucose (2-h PG) testing. FPG testing measures blood sugar levels after 8 or more hours of fasting. A FPG value of 126 mg/dl or greater is diagnostic of diabetes. The 2-h PG test is a blood sugar reading 2 hours after eating a meal. A 2-h PG value of 200 mg/dl or higher is diagnostic of diabetes3. Currently the HbA1c blood test is the most used to diagnose diabetes, and many individuals around the world are diagnosed and placed on medications based off HbA1c results alone.

But is this appropriate for individuals living at altitude? 

A groundbreaking study completed in mainland China has begun to answer this question for us. Altitudes and Hemoglobin A1c Values: An Analysis Based on Two Nationwide Cross-sectional Studies by Zheng et al was published in 2024. In this study, 95,000 adults were examined by comparing HbA1c, fasting blood glucose, and 2-hour postprandial (after a meal) glucose levels between individuals living above and below 2,500 meters (8,200 feet)4. 

A key finding of this study was that individuals living above 2,500 meters had higher HbA1c levels but the same FPG and 2-h PG results as individuals below 2,500 meters4. The individuals at altitude may have HbA1c levels that are falsely elevated. This inaccuracy can lead to an inappropriate diagnosis of diabetes in individuals living at altitude. The researchers explained that oxygen levels at higher elevations are lower, and the body reacts to these low levels by increasing levels of red blood cells and the lifespan of red blood cells. When lifespan is increased, the hemoglobin is exposed to glucose in our blood stream for longer, eliciting a higher HbA1c result despite normal blood sugar levels4. 

Another study by Bazo-Alvarez et. al in 2017 sought to evaluate the relationship between HbA1c and FPG among individuals at sea level compared to those at high altitude.

The study analyzed data from 3613 Peruvian adults without diagnosed diabetes from both sea level and high altitude (>3000m). The mean values for hemoglobin, HbA1c, and FPG differed significantly between these populations. The correlation between HbA1c and FPG was quadratic at sea level but linear at high altitude, suggesting different glucose metabolism patterns. Additionally, for an HbA1c value of 48 mmol/mol (6.5%), corresponding mean FPG values were significantly different: 6.6 mmol/l at sea level versus 14.8 mmol/l at high altitude.

These studies show that one-size-fits all screening for diabetes may not work for everyone, especially those living at altitude. Ebert Family Clinic, at 2743m (9000 ft) in the Colorado Rocky Mountains, has been researching the effects of altitude on many aspects of health including examining HbA1c levels in our residents and thus far we have seen elevated HbA1c levels in our otherwise healthy, “thin”, and active patients despite implementing appropriate lifestyle interventions to lower blood sugar. This can lead to unnecessary health anxiety that we hope to avoid by determining if HbA1c will continue to be an appropriate diagnostic tool with our residents living well above 2,500 meters.

References

1. Centers for Disease Control and Prevention. (n.d.-a). A1C test for diabetes and Prediabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/diabetes-testing/prediabetes-a1c-test.html 

2. Centers for Disease Control and Prevention. (n.d.-b). National Diabetes Statistics Report. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/php/data-research/index.html 

3. U.S. Department of Health and Human Services. (n.d.). Diabetes tests & diagnosis – NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis 

4. Zheng, R., Xu, Y., Li, M., Wang, L., Lu, J., Wang, T., Xu, M., Zhao, Z., Zheng, J., Dai, M., Zhang, D., Chen, Y., Wang, S., Lin, H., Wang, W., Ning, G., & Bi, Y. (2024). Altitudes and hemoglobin A1C values: An analysis based on two nationwide cross-sectional studies. Diabetes Care, 47(2). https://doi.org/10.2337/dc23-1549 

Acclimation, Altitude Science, Exposure, Health, High Altitude

ERUCTILE DYSFUNCTION AT ALTITUDE: Low Barometric Pressures Worsen Discomfort for Those Who Can’t Burp

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by Noor Pawar, PA-S


Retrograde Cricopharyngeus Dysfunction and the Impact of Altitude

Lucie Rosenthal’s journey, captured in her viral Reddit video, sheds light on a lesser-known condition: retrograde cricopharyngeus dysfunction, or “no-burp syndrome.” What makes her story particularly fascinating is the intersection of this medical condition with the effects of altitude—a factor that significantly influences our bodies and their functions.

In her video, Lucie joyfully discovers her ability to burp after a procedure that injects Botox into the upper esophageal muscle. However, her initial excitement turns into an uncontrollable experience that raises questions about the body’s mechanisms, especially in relation to altitude. As she recounts the bloating and discomfort that accompanied her condition, it echoes a broader issue faced by many individuals living in higher elevations, where changes in atmospheric pressure can exacerbate gastrointestinal symptoms.

The relationship between altitude and digestive health is an important consideration. At higher elevations, the reduced atmospheric pressure can lead to gas expansion in the stomach and intestines, intensifying feelings of bloating and discomfort. This is particularly relevant for individuals like Daryl Moody, who struggled with no-burp syndrome while also engaging in activities like skydiving. As he ascended, the altitude caused his stomach to inflate like a bag of chips, amplifying his discomfort and highlighting how altitude can complicate existing health issues.

The article emphasizes the growing awareness surrounding retrograde cricopharyngeus dysfunction, especially through online communities like the r/noburp subreddit. These platforms provide vital support for those affected, particularly in regions where altitude impacts digestive health. It’s a testament to how individuals can come together to share experiences and coping strategies, transforming personal struggles into a collective understanding of a shared condition.

The financial barriers mentioned in the article are further complicated for those living in high-altitude areas. With treatments often deemed “experimental” by insurance companies, individuals may face significant out-of-pocket expenses, particularly in regions where healthcare costs are already high.

Historically reports of individuals unable to burp date back centuries. The contemporary acknowledgment of retrograde cricopharyngeus dysfunction reflects an evolving understanding of how environmental factors, such as altitude, can play a crucial role in health. As we continue to learn more about this condition, the need for further research into the effects of altitude on digestive health becomes increasingly apparent.

In summary, Lucie Rosenthal’s story illustrates the complexities of retrograde cricopharyngeus dysfunction, particularly in relation to altitude. The interplay between physiological responses and environmental factors underscores the importance of patient advocacy and community support in addressing these issues. As we navigate our health, understanding how altitude can influence our bodies highlights the need for a comprehensive approach to medical care that considers all aspects of a patient’s environment.

Accessibility, Acclimation, Altitude Science, Athletic Training, Child Growth & Development, Exposure, Genetics, Health, High Altitude, Medicine, Postural Orthostatic Tachycardia Syndrome (POTS)

Thin Air Making You Lightheaded?

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by Joy Plutowski, PA-S2

Feeling lightheaded after going to a high altitude is a key symptom of acute mountain sickness (AMS)—a condition caused by the reduced oxygen available in thin mountain air. AMS often comes with other symptoms like headache, nausea, and fatigue, usually starting after a recent climb to higher elevations.

But what if it’s not just AMS? For people with conditions like postural orthostatic tachycardia syndrome (POTS), which affects blood flow and heart rate, lightheadedness at altitude could be a clue to an underlying issue. While AMS happens because of low oxygen, POTS is tied to a problem with how the nervous system regulates the body. In some cases, going to altitude might even uncover undiagnosed POTS, as symptoms can become more noticeable in these conditions.

Living With POTS

Living with POTS has been a journey of adaptation, requiring constant vigilance and adjustment to manage a complex array of symptoms. Each new environment brings its own challenges, demanding a personalized approach to maintaining stability. My recent clinical rotation in Frisco, Colorado, situated at 9,000 feet above sea level, provided an invaluable opportunity to observe firsthand how altitude influences the physiology of POTS. An overnight stay in Denver for partial acclimatization helped mitigate some initial altitude-related exacerbations, but the first few days at higher elevation were marked by pronounced symptoms, including lightheadedness, tachycardia, and insomnia. Physically demanding activities, such as snowboarding, pushed my body to its limits, resulting in extreme fatigue and heightened tachycardia. Despite these challenges, I observed gradual improvement; by the second week, I had returned to my baseline—if not better than during my time in the heat of Phoenix, Arizona. Interestingly, the colder temperatures of the region seemed to offer symptomatic relief, likely through vasoconstriction that may enhance circulation. These experiences have deepened my understanding of POTS as a highly individualized condition, emphasizing the critical importance of lifestyle modifications, environmental considerations, and a patient-specific approach to management. My journey underscores how adaptability and tailored interventions can significantly improve functionality and quality of life for those navigating the complexities of this syndrome.

What is POTS?

Postural Orthostatic Tachycardia Syndrome (POTS) is a chronic condition characterized by an abnormal increase in heart rate upon standing. It is a form of dysautonomia, involving dysregulation of the autonomic nervous system, which balances the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) systems. The autonomic nervous system regulates involuntary bodily functions such as heart rate, blood pressure, and digestion. POTS primarily affects women, with symptoms often appearing in their teens or twenties. It is estimated to affect between 1 to 3 million people in the United States, though it is likely underdiagnosed due to lack of awareness. Under normal conditions, standing triggers the body to constrict blood vessels and slightly increase heart rate to counteract gravity’s effects. In POTS, this response is impaired, leading to blood pooling in the lower extremities and reduced blood flow to the brain. The exact cause of POTS is not fully understood, but it is commonly linked to viral infections, autoimmune conditions, genetic predispositions, small fiber neuropathy, impaired norepinephrine regulation, or hypovolemia (low blood volume). Notably, long-COVID, a range of long-term symptoms and conditions resulting from an acute COVID infection, is linked to POTS. Approximately 1% of patients with an acute COVID-19 infection go on to develop orthostatic intolerance (Cheshire, 2024). Studies also show that keeping up with COVID-19 vaccinations can prevent long-COVID.

The hallmark symptom of POTS is an excessive increase in heart rate of over 30 bpm quickly after standing (WP, 2024). Common symptoms include tachycardia, palpitations, dizziness, and fainting (syncope or near-syncope), brain fog, headaches, lightheadedness, and severe fatigue. Less common symptoms include nausea, bloating, abdominal discomfort, shakiness, and exercise intolerance. POTS symptoms are often worsened by factors such as dehydration, heat, prolonged standing, illness, or physical stress. Diagnosing POTS involves a tilt-table test which monitors heart rate and blood pressure during positional changes. Treatment for POTS focuses on improving symptoms and quality of life through lifestyle adjustments. Key components include hydration, increased salt intake, compression garments, graded exercise therapy, and psychological support. Medications such as Fludrocortisone or Midodrine, that both increase blood pressure, may be added if the provider deems it fit. The course of POTS varies widely; some individuals experience significant improvement with treatment, others may have persistent symptoms. Early diagnosis and a multidisciplinary approach can lead to better outcomes.

The Effect of Altitude on the Autonomic Nervous System

Altitude significantly influences the autonomic nervous system due to reduced oxygen levels and atmospheric pressure, which challenge the body’s ability to maintain homeostasis. At higher elevations, the sympathetic nervous system becomes more active, increasing heart rate and blood pressure to compensate for lower oxygen availability. This is because hypoxia alters chemoreceptor and baroreceptor function, leading to increased sympathetic excitation and decreased parasympathetic tone.

During a study at 4300 m, urine norepinephrine levels—a marker of sympathetic activity—peaked 4–6 days after altitude exposure (Mazzeo, 1998). The study compared women in different hormonal phases when exposed to high altitude. The urinary norepinephrine levels heart rates both increased over time in both follicular and luteal phases. The differences between the two were not statistically significant, showing that women experience sympathetic increase at altitude regardless of what phase of their cycle. This was done in comparison to a previous study showing the same findings in men (Mazzeo, 1998). 

A line graph indicating the rise follicular and luteal heart rates in beats per minute as days at altitude increase.
A line graph indicating increasing amounts per 24 hours of urinary norepinephrine.

Other physiological responses include increased ventilation, cardiac output, and heart rate. However, with acclimatization, heart rate and cardiac output typically return to sea-level values within 9–12 days (Hainsworth et al., 2007). Over time, improved oxygen-carrying capacity enhances tolerance to orthostatic stress. All in all, orthostatic tolerance during hypobaric hypoxia involves three mechanisms: cardiovascular control of heart rate and cardiac output, cerebrovascular responses to hypocapnic hypoxia (due to hyperventilation), and elevated sympathetic activity (Blaber et al., 2003). 

For individuals with POTS, altitude-related stresses may exacerbate symptoms. Hypoxia and reduced barometric pressure can worsen fatigue, brain fog, and dizziness by increasing the body’s effort to oxygenate tissues. Reduced oxygen delivery to the brain and tissues may intensify lightheadedness and syncope— which is already common in POTS.

Although acclimatization typically occurs within 1–2 weeks at altitude in healthy individuals, research on acclimatization in POTS patients is limited. Further studies are needed to determine whether individuals with autonomic dysfunction can adapt as effectively as those without.

Living With POTS at Altitude 

Living with POTS at altitude presents unique challenges that require careful management, as patients may find it harder to adapt to the altitude-induced changes in blood oxygenation and pressure regulation. These challenges are compounded by the existing difficulties they face in maintaining autonomic stability. The reduced oxygen levels and increased demands on the cardiovascular system can amplify POTS symptoms, making daily activities more difficult. Patients with POTS generally understand their triggers and have a protocol that was formulated with their provider. Such strategies include staying well-hydrated, using compression garments, increasing salt intake, decreasing alcohol and caffeine consumption, and avoiding sudden changes in posture. Also, gradual exposure to altitude helps the body adapt to the reduced oxygen and barometric pressure, minimizing symptom flares. For individuals with POTS visiting high-altitude environments, strict adherence to their treatment regimen, including lifestyle modifications and potentially pharmacologic interventions, is paramount for managing their condition effectively.

References

Blaber AP, Hartley T, Pretorius PJ (2003) Effect of acute exposure to 3,660 m altitude on orthostatic responses and tolerance. J Appl Physiol 95:591–601

Cheshire WP. (2024) Postural tachycardia syndrome. UpToDate. 

Hainsworth, R., Drinkhill, M. J., & Rivera-Chira, M. (2007). The autonomic nervous system at high altitude. Clinical autonomic research : official journal of the Clinical Autonomic Research Society, 17(1), 13–19

Mazzeo RS, Child A, Butterfield GE, et al. (1998) Catecholamine response during 12  days of high-altitude exposure (4,300 m) in women. J Appl Physiol 84:1151–1157

Joy Plutowski is a second-year PA student born and raised in Arizona. She completed her undergraduate degree in biology at Arizona State University and is now pursuing her master’s at Midwestern University in Glendale, AZ. Before PA school, she worked as a medical scribe for an interventional cardiologist, a field she is interested in pursuing. Currently, she has the wonderful opportunity of completing her pediatrics rotation in Frisco, CO. In her free time, Joy enjoys exploring national parks, playing video games, dancing, and most recently, snowboarding. 

Acclimation, Altitude Science, Exposure, Genetics, Health, High Altitude

Boy Scouts and Skiers: Reducing the Risk of Developing Acute Mountain Sickness

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Thousands of boy scouts travel to Philmont Scout Ranch (PSR) in Cimarron, New Mexico each year in hopes of improving their wilderness survival skills by ascending its rugged, mountainous terrain. Elevations at PSR range from 2011 to 3792 m, in sharp contrast to the lower elevations the boy scouts are used to. Those with a history of daily headaches, gastrointestinal illnesses, and prior acute mountain sickness were found to be most at risk of developing altitude related illnesses while ascending PSR. The incidence of acute mountain sickness was 13.7% at PSR when participants ascended from base camp (2011 m) to 3000m+ as compared to up to 67% in other staged ascent studies [3]. Similarly to PSR, millions of people ascend the Colorado Rocky Mountains during ski season and face the same potential complications. This risk makes it abundantly important to investigate potential ways to prevent the development of altitude related illnesses.

Oxygen from inspired air (air breathed in) flows down its concentration gradient from the alveolar space into the blood, where it is carried primarily bound to hemoglobin and delivered to tissue. At high altitudes, oxygen availability and barometric pressure decrease remarkably, hindering the concentration gradient and increasing the risk of tissue hypoxia [2]. Progressive tissue hypoxia eventually leads to high altitude illnesses (HAI), which are cerebral and pulmonary syndromes resulting from rapid ascent. The likelihood of developing these disease processes can be greatly reduced if the body is given time to acclimate to the increased altitude. This is especially relevant during the holidays, when many are traveling from lower altitudes to higher altitudes abruptly for vacation or to visit with family.

This raises the question: should travelers spend the night in Denver before ascending into the mountains to allow for acclimatization and reduce the risk of HAI?

The rate of acclimatization, or the body’s ability to adjust to and accommodate increased oxygen requirement, is difficult to generalize given rate of ascension is not the only factor that influences the development of HAI. This process can take anywhere from days to potentially months depending on a number of factors including cardiopulmonary comorbidities, a history of HAI, genetics, certain medications, substance usage, and degree of physical exertion amongst others [5].

Despite the multifactorial nature of developing HAI, rate of ascent remains one of the primary risk factors. Studies have shown that spending time at moderate altitude before ascending to higher altitudes in a process called “staged ascent” decreases the likelihood of developing HAI in unacclimatized individuals [4]. A recent study conducted at the U.S. Army Research Institute of Environmental Medicine assessed incidence of acute mountain sickness (AMS, a subcategory of HAI), in unacclimatized individuals who were staged for 2 days at altitudes of 2500 m, 3000 m, and 3500 m respectively before ascending to 4300 m. Another group ascended directly to 4300 m without staging. Ultimately, the incidence of AMS was significantly lower in the staged groups than in the direct ascent group; AMS incidence in the staged groups was up to 67%, while AMS incidence in the direct ascent group was up to 83% [1].

Two graphs, A and B, illustrate the incidence of acute mountain sickness by percent at elevations of 2500m, 3000m, 3500m and a control group, as well as peak acute mountain sickness severity ranked from 0 to 2 for the same elevations and a control group.

Graphs A and B show that the incidence of AMS at 4300 m is reduced when unacclimatized individuals are staged at 2500 m, 3000 m, and 3500 m as compared to those who directly ascended to 4300 m [1].

Given the above information, unacclimatized individuals, skiers and boy scouts alike, may benefit from spending the night in Denver before coming to the mountains, as this mimics staged ascent and thus decreases the incidence of HAI.

Tall, snowy pines rise up out of powdery snow on a ski slope overlooking forests stretching out toward a range of white peaks in the distance under a sunny blue sky.
View from the top of Keystone Resort taken while snowboarding (elevation 3782 m)

References

[1] Beth A. Beidleman et al. “Acute Mountain Sickness is Reduced Following 2 Days of Staging During Subsequent Ascent to 4300m”. In: High Altitude Medicine & Biology 19.4 (2018). Published Online: 21 December 2018, pp. xxx–xxx. doi: 10.1089/ham.2018.0048. 

[2] Chris Imray et al. “Acute Mountain Sickness: Pathophysiology, Prevention, and Treatment”. In: Progress in Cardiovascular Diseases 52.6 (May 2010), pp. 467–484. doi: 10.1016/j.pcad.2009.11.003.

[3] Courtney LL Sharp et al. “Incidence of Acute Mountain Sickness in Adolescents Backpacking at Philmont Scout Ranch”. In: Wilderness and Environmental Medicine 35.4 (2024), pp. 403-408

[4] Andrew M. Luks, Erik R. Swenson, and Peter B¨artsch. “Acute high-altitude sickness”. In: European Respiratory Review 26.143 (Jan. 2017), p. 160096. doi: 10.1183/16000617.0096-2016.

[5] Michael Schneider et al. “Acute mountain sickness: influence of susceptibility, preexposure, and ascent rate”. In: Medicine & Science in Sports & Exercise 34.12 (Dec. 2002), pp. 1886–1891

Matison Miratsky is a physician assistant student who attends Midwestern University in Arizona with plans to go into OB/GYN. Before PA school, she grew up in Denver, Colorado and attended the University of Colorado at Boulder. She worked in an emergency department in Denver, then at a family medicine clinic in Arizona. Her personal interests include snowboarding, watching movies, spending time with family, and cooking.

Altitude Science, Backpacking, Exposure, Health, High Altitude, Mountaineering, Wildlife

­­Avon skin so soft as a mosquito repellent? It’s not just an old wives’ tale!

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by Megan Furry, PA-S

The common thought that mosquitos do not live at higher elevations may no longer be true. With temperatures slowly rising, we are seeing a rise in mosquito populations at higher elevations and farther north than we have before.1 Mosquitos are having luck finding their ideal conditions with standing water, higher temperature, and humidity at higher elevations.

As of June 27, 2024, the state of Colorado had already seen its first case of West Nile Virus for the year, something that does not usually occur until late in the summer. In 2023, Colorado dealt with its worst West Nile virus outbreak ever recorded.2 As we are beginning to see more and more mosquitos in our community, people are looking for the best and safest mosquito repellents.

The most common big hitters when it comes to bug spray are DEET-containing bug sprays and those that say DEET-free. If your mom is like mine and used to tell you that Avon Skin So Soft is a great mosquito repellent, I’m here to help you determine if it actually does work. A study published in the BC Medical Journal compared DEET-containing mosquito repellent, Avon Skin So Soft bath oil, and a “special mixture” containing a combination of eucalyptus oil, white vinegar, Avon Skin So Soft, and tap water, against a placebo. They found that both DEET and Avon Skin So Soft protected against mosquito bites significantly more than the “special mixture.” In this study, Avon Skin So Soft was 85% as effective as DEET at protecting against mosquito bites. Looking strictly at the numbers, DEET had 0 mosquito events (both bites and mosquitos landing on the skin), Avon Skin So Soft bath oil had 6 events, the “special mixture” had 28 events, and the placebo had 40 events.3

From personal experience, I have tested out Avon Skin So Soft and its mosquito repellent properties. In August 2019 I ventured halfway across the world to Thailand for a post-undergraduate adventure. With limited packing room and a dislike for the smell of bug spray, I brought Avon Skin So Soft body moisturizer with me and was pleasantly surprised with how well it kept the mosquitos away.

Avon has made a specific bug repellent line of products that claims to protect against mosquitos, deer ticks, black flies, gnats, and biting midges.

For our furry friends that tag along with us on all of our outdoor adventures, remember that they too can get bitten by pesky insects. They are still susceptible to mosquito bites as well as ticks and fleas. At altitude we see less ticks and fleas in our communities due to the dry air, however they are still present, so it is important to protect your animals like you do yourself. Some veterinarian recommended tick and flea prevention include Simparica Trio or Nexgard chewables.

References

  1. Today E. Mosquito Migration: Study Finds More High-Altitude Dispersal of Disease Vectors in Africa. Entomology Today. Published May 5, 2023. https://entomologytoday.org/2023/05/05/mosquito-migration-more-high-altitude-dispersal-disease-vectors-africa-malaria/#:~:text=The%20studies%20leave%20no%20doubt
  2. UCHealth KKM. Colorado records first 2024 West Nile case, after worst U.S. outbreak in 2023. UCHealth Today. Published June 27, 2024. https://www.uchealth.org/today/west-nile-virus-in-colorado/
  3. Mosquito repellent effectiveness: A placebo controlled trial comparing 95% DEET, Avon Skin So Soft, and a “special mixture” | British Columbia Medical Journal. bcmj.org. https://bcmj.org/articles/mosquito-repellent-effectiveness-placebo-controlled-trial-comparing-95-deet-avon-skin-so
Acclimation, Altitude Science, Asthma, Child Growth & Development, COVID-19, Doc Talk, Exposure, Genetics, Health, High Altitude, Medicine, Mountaineering, Pandemic, Sleep at Altitude, Technology

Can I Ever Go Back Up To High Altitude Again? – Recurrence Risk of HAPE & HARPE

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by Taylor Kligerman, PA-S

Can I ever return to high altitude? Do I need to move down to a lower elevation?

Disease processes often differ at high altitudes. Some conditions have only been known to occur at high elevations. Most of the resources cited in this blog refer to ‘high altitude’ being at or above 2,500 meters or 8,200 feet.

Ebert Family Clinic in Frisco, Colorado is at 9,075 ft. Many areas in the immediate vicinity are over 10,000′, with some patients living above 11,000′. Two of the more common conditions seen in patients at Ebert Family Clinic are high altitude pulmonary edema (HAPE) and high altitude resident pulmonary edema (HARPE), similar conditions that affect slightly different populations in this region of the Colorado Rocky Mountains.

In “classic” HAPE, a visitor may come from a low-altitude area to Frisco on a trip to ski with friends. On the first or second day, the person notices a nagging cough. They might wonder if they caught a virus on the plane ride to Denver. The cough is usually followed by shortness of breath that begins to make daily tasks overwhelmingly difficult. One of the dangerous aspects of HAPE is a gradual onset leading patients to believe their symptoms are caused by something else. A similar phenomenon is seen in re-entry HAPE, where a resident of a high altitude location travels to low altitude for a trip and upon return experiences these same symptoms [1].

In HARPE, a person living and working here in Frisco may be getting ill or slowly recovering from a viral illness and notices a worsening cough and fatigue. These cases are even more insidious, going unrecognized, and so treatment is sought very late. Dr. Christine Ebert-Santos and her team at Ebert Family Clinic hypothesize that while residents have adequately acclimated to the high-altitude environment, the additional lowering of blood oxygen due to a respiratory illness with inflammation may be the inciting event in these cases.

In both cases, symptoms are difficult to confidently identify as a serious illness versus an upper respiratory infection, or simply difficulty adjusting to altitude. For this reason, Dr. Chris recommends that everyone staying overnight at high altitude obtain a pulse oximeter. Many people became familiar with the use of these instruments during the COVID-19 pandemic. The pulse oximeter measures what percent of your blood is carrying oxygen. At high altitude, a healthy level of oxygenation is typically ≥90%. This is an easy way to both identify potential HAPE/HARPE, as well as reassure patients they are safely coping with the high-altitude environment [2].

HAPE and HARPE are both a direct result of hypobaric hypoxia, a lack of oxygen availability at altitude due to decreased atmospheric pressures. At certain levels of hypoxia, we observe a breakdown in the walls between blood vessels and the structures in lungs responsible for oxygenating blood. The process is still not totally understood, but some causes of this breakdown include an inadequate increase in breathing rates, reduced blood delivered to the lungs, reduced fluid being cleared from the lungs, and excessive constriction of blood vessels throughout the body. These processes cause fluid accumulation throughout the lungs in the areas responsible for gas exchange making it harder to oxygenate the blood [3].

We do know that genetics play a significant role in a person’s risk of developing HAPE/HARPE. Studies have proposed many different genes that may contribute, but research has not, so far, given healthcare providers a clear picture of which patients are most at-risk. Studies have shown that those at higher risk of pulmonary hypertension (high blood pressure in the blood vessels of your lungs), are more likely to develop HAPE [4]. This includes some types of congenital heart defects [5,6]. High blood pressures in the lungs reach a tipping point and appear to be the first event in this process. However, while elevated blood pressures in the lungs are essential for HAPE/HARPE, this by itself, does not cause the condition. The other ingredient necessary for HAPE/HARPE to develop is uneven tightening of the blood vessels in the lungs. When blood vessels are constricted locally, the blood flow is shifted mainly to the more open vessels, and this is where we primarily see fluid leakage. As the blood-oxygen barrier is broken down in these areas, we may also see hemorrhage in the air sacs of the lungs [3].

One observation healthcare providers and scientists have observed is that HAPE/HARPE can be rapidly reversed by either descending from altitude or using supplemental oxygen. Both strategies increase the availability of oxygen in the lungs, reducing the pressure on the lungs’ blood vessels by vasodilation, quickly improving the integrity of the blood-oxygen barrier.

In a preliminary review of over 100 cases of emergency room patients in Frisco diagnosed with hypoxemia (low blood oxygen content) Dr. Chris and her team have begun to see trends that suggest the availability of at-home oxygen markedly reduces the risk of a trip to the hospital. This demonstrates that patients with both at-home pulse oximeters and supplemental oxygen have the capability to notice possible symptoms of HAPE, assess their blood oxygen content, and apply supplemental oxygen if needed. This stops the development of HAPE/HARPE before damage is done in the lungs. In the case of many of our patients, these at-home supplies prevent emergencies and allow patients time to schedule an appointment with their primary care provider to better evaluate symptoms.

Additionally, Dr. Chris and her team have observed that patients with histories of asthma, cancer, pneumonia, and previous HAPE/HARPE are often better educated and alert to these early signs of hypoxia and begin treatment earlier on in the course of HAPE/HARPE, reducing the relative incidence identified by medical facilities. There are many reasons to seek emergent care such as low oxygen with a fever. Patients with other existing diseases causing chronically low oxygen such as chronic lung disease may not be appropriately treated with  supplemental oxygen, although this is a very small portion of the population. Discussions with healthcare providers on the appropriate prevention plan for each patient will help educate and prevent emergency care visits in both residents and visitors.

A young child with short brown hair and glasses with dark, round frames wears a nasal canula for oxygen.

Studies of larger populations have yet to be published. A review of the case reports in smaller populations suggests that the previously estimated recurrence rate of 60-80% is exaggerated. This is a significant finding as healthcare providers have relied on this recurrence rate to make recommendations to their patients who have been diagnosed with HAPE. A review of 21 cases of children in Colorado diagnosed with HAPE reported that 42% experienced at least one recurrence [7]. This study was conducted by voluntary completion of a survey by the patients (or their families) which could lead to significant participation bias affecting the results. Patients more impacted by HAPE are more likely to complete these surveys. Another study looking at three cases of gradual re-ascent following an uncomplicated HAPE diagnosis showed no evidence of recurrence. The paper also suggested there may be some remodeling of the lung anatomy after an episode of HAPE that helps protect a patient from reoccurrence [8]. Similar suggestions of remodeling have been proposed through evidence of altitude being a protective factor in preventing death as demonstrated by fatality reports from COVID-19[9].

A review article from 2022 by Ucros et al showed a recurrence rate of 21%, high among mountain residents who travel to lower altitudes and develop reentry HAPE. An ongoing analysis of 248 hypoxic children seen in the emergency department in Frisco, Colorado at 9,000 feet found a recurrence of around 40%, again mostly reentry HAPE and HARPE, since residents have a much higher exposure to the hypoxic environment adding to their risk. Rick for visitors with classic HAPE is difficult to determine, as they are unlike to be seen in the same medical facility, but the medical history taken during the encounters in this study do not reflect any recurrence.

Without larger studies and selection of participants to eliminate other variables like preexisting diseases, we are left to speculate on the true rate of reoccurrence based on the limited information we have. Strategies to reduce the risk of HAPE/HARPE such as access to supplemental oxygen, pulse oximeters, and prescription medications [10] are the best way to prevent HAPE/HARPE. Research should also continue to seek evidence of individuals most at risk for developing HAPE/HARPE [11].

A woman with reddish-brown, straight hair just below her shoulders, wears a white coat over a mustard-colored shirt, smiling.

Taylor Kligerman is a third-year medical student at Rocky Vista University with plans to complete a residency in emergency medicine. She was born and raised in Flossmoor, IL, and became interested in medicine following her first medical mission trip to Gonaïves, Haiti in 2010. Taylor has extensive experience in wilderness and remote emergency medicine. Before starting medical school, she was certified as a wilderness EMT and gained experience in remote areas of Canada and Western North Carolina on whitewater expeditions and as a volunteer with local search and rescue. Her personal interests include camping, skiing, and all paddle sports.

References

  1. Ucrós S, Aparicio C, Castro-Rodriguez JA, Ivy D. High altitude pulmonary edema in children: A systematic review. Pediatr Pulmonol. 2023;58(4):1059-1067. doi:10.1002/ppul.26294
  2. Deweber K, Scorza K. Return to activity at altitude after high-altitude illness. Sports Health. 2010;2(4):291-300. doi:10.1177/1941738110373065
  3. Bärtsch P. High altitude pulmonary edema. Med Sci Sports Exerc. 1999;31(1 Suppl):S23-S27. doi:10.1097/00005768-199901001-00004
  4. Eichstaedt C, Benjamin N, Grünig E. Genetics of pulmonary hypertension and high-altitude pulmonary edema. J Appl Physiol. 2020;128:1432
  5. Das BB, Wolfe RR, Chan K, Larsen GL, Reeves JT, Ivy D. High-Altitude Pulmonary Edema in Children with Underlying Cardiopulmonary Disorders and Pulmonary Hypertension Living at Altitude. Arch Pediatr Adolesc Med. 2004;158(12):1170–1176. doi:10.1001/archpedi.158.12.1170
  6. Liptzin DR, Abman SH, Giesenhagen A, Ivy DD. An Approach to Children with Pulmonary Edema at High Altitude. High Alt Med Biol. 2018;19(1):91-98. doi:10.1089/ham.2017.0096
  7. Kelly TD, Meier M, Weinman JP, Ivy D, Brinton JT, Liptzin DR. High-Altitude Pulmonary Edema in Colorado Children: A Cross-Sectional Survey and Retrospective Review. High Alt Med Biol. 2022;23(2):119-124. doi:10.1089/ham.2021.0121
  8. Litch JA, Bishop RA. Reascent following resolution of high altitude pulmonary edema (HAPE). High Alt Med Biol. 2001;2(1):53-55. doi:10.1089/152702901750067927
  9. Gerken J, Zapata D, Kuivinen D, Zapata I. Comorbidities, sociodemographic factors, and determinants of health on COVID-19 fatalities in the United States. Front Public Health. 2022;10:993662. Published 2022 Nov 3. doi:10.3389/fpubh.2022.993662
  10. Luks A, Swenson E, Bärtsch P. Acute high-altitude sickness. European Respiratory Review. 2017;26: 160096; DOI: 10.1183/16000617.0096-2016
  11. Dehnert C, Grünig E, Mereles D, von Lennep N, Bärtsch P. Identification of individuals susceptible to high-altitude pulmonary oedema at low altitude. European Respiratory Journal 2005;25(3):545-551; DOI: 10.1183/09031936.05.00070404
Accessibility, Acclimation, Altitude Science, Asthma, Child Growth & Development, Doc Talk, Exposure, Genetics, Health, High Altitude, Medicine

Hypoxia in the Emergency Department: Preliminary Analysis of Data from the Highest Atitude Population in North America & Children with Hypoxia

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Hypoxia is a common presentation at the emergency department for the St Anthony Summit Medical Center, located at 2800 meters above sea level (msl) in Colorado. Children under 18 are brought in with respiratory symptoms, trauma, congenital heart and lung abnormalities, and high altitude pulmonary edema (HAPE). Many complain of shortness of breath and/or cough and are found to be hypoxic, defined as an oxygen saturation below 89% on room air for this elevation. Patients who live at altitude may perform home pulse oximetry and arrive for treatment and diagnosis of known hypoxia. Extensive and ongoing analysis of the data from children found to be hypoxic in the emergency department raises many questions, including how residents vs nonresidents present, how often  these cases are preceded by febrile illness and what chief complaint is most frequently cited. 

Understanding the presentation of hypoxia in children at altitude can help ensure that healthcare providers are following a comprehensive approach with awareness of the overlapping symptoms of HAPE, pneumonia and asthma. Below is a graphic summary of 36 cases illustrating the clinical, social and geographic factors contributing to hypoxia at altitude in residents and visitors. A further analysis of over 200 children with hypoxia presenting to the emergency room at 9000 feet is underway including x-ray findings.

The graphs below were created by the author, using data extracted directly from a review of patient charts (specifically, those of children presenting to the local hospital in Summit County, Colorado (9000 feet) with hypoxia).

Graphs 1-4 show chief complaints of cough (CC) and shortness of breath (SOB) compared by age and by residence (res: includes altitudes above 2100 meters above sea level), the front range (a high altitude region of the Rocky Mountains running north-south between Casper, Wyoming and Pueblo, Colorado) averaging 1500 msl, and out of the state of Colorado (OOS).

Graphs 9 and 10 show lowest oxygen by age at admission and lowest O2 organized by days spent in the county (residents are excluded from this data). 

Erin Snyder is a new graduate physician assistant who graduated this fall after spending her final rotation in Frisco with the Ebert clinic. She is now working in pediatric hematology at Children’s Hospital Colorado. And her free time she enjoys skiing, hiking and spending time with her cat Charlie.

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

Doc Talk: Physician Altitude Experts on High Altitude Pulmonary Edema (HAPE)

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One of our students recently came across a comprehensive publication on high altitude pulmonary edema (HAPE) on reputable point-of-care clinical resource UpToDate.com1, citing Christine Ebert-Santos, MD, MPS, the founder of highaltitudehealth.com.

Emergency medicine physician at Aspen Valley Hospital and medical director for Mountain Rescue Aspen since 1997 Dr. Scott A. Gallagher2 and emergency physician and altitude research pioneer Dr. Peter Hackett3 introduce the resource warning, “Anyone who travels to high altitude, whether a recreational hiker, skier, mountain climber, soldier, or worker, is at risk of developing high-altitude illness.”

Ebert-Santos’s (known affectionately to her patients and mountain community as “Dr. Chris”) own research is referenced in the article’s discussion of epidemiology and risk factors noting an additional category of HAPE among “children living at altitude who develop pulmonary edema with respiratory infection but without change in altitude,”4 whereas the two other recognized categories (classic HAPE and re-entry HAPE) typically happen in response to a change in altitude.

The article continues with figures illustrating how ascending too quickly or too much can dramatically increase risk: “HAPE generally occurs above 2500 meters (8000 feet) and is uncommon below 3000 meters (10,000 feet) … The risk depends upon individual susceptibility, altitude attained, rate of ascent, and time spent at high altitude. in those without a history of HAPE, the incidence is 0.2 percent with ascent to 4500 meters (14,800 feet) over four days but 6 percept when ascent occurs over one to two days. In those with a history of HAPE, recurrence is 60 percent with an ascent to 4500 meters over two days. At 5500 meters (18,000 feet), the incidence ranges between 2 and 15 percent, again depending upon rate of ascent.”

Dr. Chris discusses her experience treating her pediatric patients at high altitude in more depth in an interview with pediatric emergency medicine physician Dr. Alison Brent from Colorado Children’s Hospital for the podcast Charting Pediatrics.

Dr. Gallagher and Dr. Hackett’s article is available on UpToDate with a subscription.

References

  1. https://www.uptodate.com/contents/high-altitude-pulmonary-edema?source=autocomplete&index=0~1&search=HAPE ↩︎
  2. https://www.aspenhospital.org/people/scott-a-gallagher-md/ ↩︎
  3. https://www.highaltitudedoctor.org/dr-peter-hackett ↩︎
  4. Ebert-Santos, C. High-Altitude Pulmonary Edema in Mountain Community Residents. High Alt Med Biol 2017; 18:278. ↩︎