Category Archives: Mountaineering

Already an extreme sport, mountaineering at high altitudes adds exponential risk! Know before you go!

When Altitude gets High, does Stroke get higher?

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.

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

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 previous 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, Re-entry HAPE in High Altitude Residents.

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.  The University of Heidelberg recently published an article on the genetics of pulmonary hypertension (HARPE is the New HAPE) and is interested in testing families here who have had more than one person affected by HAPE.

High-Altitude Pulmonary Edema is not just for tourists

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/

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

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.

Sleep at High Altitude

Have you thought of what it would be like living in the mountains year-round? Medical professionals find it is important to look at what living at high elevations can do to the human body. One activity heavily affected is sleep. As mentioned in previous blog posts, visitors often have trouble falling asleep, staying asleep, and feeling rested in the morning. A recent study published in Physiological Reports measured the effects of sleeping patterns at high elevation. The participants experienced a simulated elevation inside a hyperbaric chamber. This mimicked sleeping at elevations of 3000 meters (9,842 feet) and 4050 meters (13,287 ft) for one night and then sleeping at sea level for several nights to establish a baseline for the research participants. Participants exercised for 3 hours in the hyperbaric chamber allowing researchers to observe how the lower oxygen concentrations affected their ability to perform strenuous tasks. The group that slept in a simulated 4050 meter environment had an increased heart rate that was 28% higher and an oxygen saturation 15% lower than the 3000 meter participants. When comparing sleep itself, the group at 4050 meters had 50% more awakening events throughout each night. This goes along with previous research on this blog that states that people who sleep at high altitude complain of insomnia and frequent awakening when first arriving at high elevation.

These numbers increase even more dramatically when compared to participants at sea level. Related symptoms reported during this study showed the incidence of acute mountain sickness occurred in 10% of the participants at a simulated 3000 meters, increasing to 90% at 4050 meters. As mentioned, the average heart rate increases and oxygen saturation decreases as the elevation increases. The baseline heart rate at sea level was 62 beats per minute, increasing to 80 at 3000 meters and 93 at 4050 meters. Ideally health care providers aim to oxygenate vital organs by keeping the oxygen saturation level between 92-100%. The lower the oxygen level the harder it is to keep organs properly profused. Age, health status, and place of residence are taken into consideration when examining study reports. Oxygen saturation at sea level was 98% decreasing to 92% at 3000 meters and 84% at 4050 meters.

As mentioned in a previous post by Dr. Neale Lange, sleeping at high altitudes can be hard due to the frequent awakenings and nocturnal hypoxia caused by the low oxygen levels at higher elevation. This study reiterates these findings with the results of the average oxygen saturation at 3000 meters being around 92%. Dr. Lange also found that sleep apnea was often more prominent and had more negative effects on the human body in environments that were lower in oxygen. This study agrees with that statement finding that people with sleep apnea had twice the hourly awakenings compared to those at higher elevation that did not have sleep apnea. Dr. Lange also pointed out that the contribution of hypobaric atmosphere to symptoms at altitude as opposed to pure hypoxemia is unknown. Frisco, Colorado is at an elevation of 2800 meters. Ongoing research at Ebert Family Clinic including residents and visitors along with laboratory studies such as this one can guide decisions about interventions and treatment to improve sleep and help us enjoy our time in the mountains.

References

  1. Figueiredo PS, Sils IV, Staab JE, Fulco CS, Muza SR, Beidleman BA. Acute mountain sickness and sleep disturbances differentially influence cognition and mood during rapid ascent to 3000 and 4050 m. Physiological Reports. 2022;10(3). doi:10.14814/phy2.15175
  2. Blog post: HOW DO YOU DEFINE A GOOD NIGHT’S SLEEP?:AN INTRODUCTION TO THE SLEEPIMAGE RING, AN INTERVIEW WITH DR. NEALE LANGE

Casey Weibel is a 2nd year student at Drexel University, born and raised in Pittsburgh, Pennsylvania. He went to Gannon University for his undergrad and got a degree in biology.  Before PA school, Casey was an EMT.  He enjoys hiking and kayaking and is a big sports fan. 

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

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.

How to Stay Healthy During Your Holidays at High Altitude

Acute Altitude Illness affects about 7.4% of travelers to mountain resort areas, including Frisco, Colorado which sits at an altitude of about 2800 meters. Dr. Kendrick Adnan, MD, MSPH is an emergency medicine physician associated with Vail Health. Dr. Adnan often sees visitors to Vail and other popular ski and vacation areas in Summit County that are experiencing Acute Altitude Illness. I sat down with Dr. Adnan, and we discussed the treatment of Acute Altitude Illness as well as signs, symptoms, risk factors, and prevention of Acute Altitude Illness.

What causes Acute Altitude Illness?

  • Acute Altitude Illness develops when the body responds to hypoxia, a low level of oxygen in the blood. Areas of high altitude have a lower concentration of oxygen in the air than lower altitudes, which makes your body work harder to put oxygen in your blood. Your body responds to the lower oxygen concentration by increasing how often and how deeply you breathe. This causes a decrease in carbon dioxide and increase in tpH in the blood. Your heart, lungs, blood vessels, and kidneys all respond to the low pH in your blood, which can cause the signs and symptoms of Acute Altitude Illness.
  • Some people will experience severe forms of Acute Altitude Illness called High-Altitude Pulmonary Edema or High-Altitude Cerebral Edema. These are life-threatening conditions that can cause death in both adults and children if not treated promptly by a medical professional.

What are the signs and symptoms of Acute Altitude Illness in adults?

  • Headache
  • Nausea
  • Vomiting
  • Decreased appetite
  • Fatigue
  • Shortness of breath on exertion
  • Decreased exercise tolerance
  • Chest tightness
  • Hypoxia

What are the signs and symptoms of Acute Altitude Illness in children?

  • Fussiness
  • Poor feeding
  • Pale or blue-tinged skin
  • Sleeping too much or too little

What is the treatment for Acute Altitude Illness (AAI)?

The best treatment for AAI is supplemental oxygen through a nasal cannula and descent to a lower elevation. You will need to visit a healthcare provider, clinic, or hospital to get supplemental oxygen if your oxygen level drops below 89%. Visitors to high-altitude areas may be hesitant to abandon their vacation plans in order to descend to a lower altitude. A healthcare provider may be able to prescribe medications to help you recover from AAI. However, if your low oxygen level does not improve with supplemental oxygen and medication, it is important to descend to an area of lower altitude.

Studies show that acetazolamide, dexamethasone, and tadalafil are medications that can potentially treat Acute Altitude Illness and/or High-Altitude Pulmonary Edema. A healthcare provider may prescribe these medications for you if appropriate.

What increases the chance that I will experience Acute Altitude Illness?

  • Traveling by airplane from low altitude to high altitude.
  • Being a resident of low altitude
  • Past episode of Acute Altitude Illness
  • Physical exertion at high altitude, especially in colder temperatures

What can be done to prevent Acute Altitude Illness and High-Altitude Pulmonary Edema?

  • A slower ascent will decrease your risk of AAI. Dr. Adnan recommends spending the night in Denver after air travel if you are planning to visit a high-altitude area.
  • Avoid strenuous exercise like skiing, hiking, and mountain biking for 48-72 hours after arrival to a high-altitude area.
  • Buy a pulse oximeter to check your oxygen level. A level above 89% is normal at high-altitude and does not require treatment.
  • Ask your healthcare provider about taking Diamox (acetazolamide) for 2-3 days before you arrive at a high-altitude destination. You will need a prescription for this medication.
  • Avoid medications that decrease your respiratory rate like opiates, sleeping medications, benzodiazepines, and barbiturates.

References

Schafermeyer, R. W. DynaMed. Acute Altitude Illnesses. EBSCO Information Services. https://www.dynamed.com/condition/acute-altitude-illnesses. Accessed November 19, 2021. Simancas-Racines D, Arevalo-Rodriguez I, Osorio D, Franco JVA, Xu Y, Hidalgo R. Interventions for treating acute high altitude illness. Cochrane Database of Systematic Reviews 2018, Issue 6. Art. No.: CD009567. DOI: 10.1002/14651858.CD009567.pub2. Accessed 03 November 2021.

Sasha Scott is a physician assistant student at Drexel University in Philadelphia, PA. She is originally from Indianapolis, IN and attended Purdue University for undergrad. Sasha enjoys running, cross stitching, cooking, and exploring Philadelphia when she is not studying!

Effects of High Altitude on Brain Metabolism & Concussion Information

Changes in altitude have many effects on the physiology of the human body and even metabolism. Some people exposed to high altitude develop acute or chronic mountain sickness due to hypoxia with a spectrum of symptoms including neurocognitive decline of performance and impacting brain function. Head truma at altitude is more likely to lead to brain injury or concussion than those at low altitude.

Imaging with PET/CT using FDG-18 has been used to measure brain metabolism in both human and mice subjects. This type of imaging scans the accumulation of a glucose analog in tissue, specifically the brain in this case. This allows determination of which regions have high or low uptake in metabolism in comparison to a brain at baseline at sea level.

In 2017, mice were studied by being placed in a hypobaric chamber to stimulate hypoxic conditions similar at 5000 meters. Conditions were placed to minimize brown adipose tissue uptake and imaging was performed 45 minutes after an estimated 0.5 mCi FDG injection. After appropriate processing, the results showed an increase in glucose metabolism in the cerebellum and medulla of the mice exposed to high altitude conditions compared to those at baseline. Additionally, certain cortical regions had lower metabolism than baseline mice, and lower cardiac uptake as well. It is thought that the brain’s acclimation response to high altitude.

Images courtesy of Jaiswal S., et al. JNM 2017.

Another study using mice as subjects compared brain metabolism at high altitude after a traumatic brain injury (TBI) to determine if hypoxia alters glucose uptake. A total of 32 mice were imaged at sea level (baseline) and again after 12 weeks exposure at 5000m (hypobaric stimulation), and again after a repetitive closed injury. An SUV (standard uptake value) was compared in each set of images to determine a change in glucose metabolism. 

This study showed a significant increase in FDG uptake in the medulla, cerebellum, and pons, and a decreased uptake in the corpus callosum, cortex, midbrain, and thalamus. A TBI affects glucose metabolism in the brain by decreasing cortical uptake in both high altitude and sea level. This study showed that high altitude affects the brain by making it more susceptible to repeated concussions than mice at sea level.

A third study employed PET/CT imaging to assess regional cerebral glucose metabolism rates in six US Marines before and after a rigorous training period from sea level to high altitude conditions ranging from 10,000-20,000 ft. It was thought that other conditions would be relatively stable as the military has similar regimens for their members. After comparing imaging performed at baseline sea level and after two months of high-altitude exposure, it was clear that brain metabolism changed. There was a decrease in glucose metabolism in three frontal regions, left occipital, and right thalamus. Right and left cerebellum showed an increase in glucose uptake and metabolism.

Red and orange coloring signifies greater FDG-18 uptake which correlates to increased glucose metabolism. The post imaging signifies decreased uptake and hypometabolism of certain brain regions as mentioned previously. Image courtesy of Hochachka PW., et al. AJP, 1999.

The data from these three studies clearly show high altitude exposure with hypoxia changes the way our brain tissue metabolism functions. Studies show Sherpas, native to the Himalayas are the most well adapted high-altitude humans.  Their brain metabolism is the same of that of “low-landers”. Conversely, the Quechuas who are native to the Andes of South America still show small amounts of hypometabolism in their brain. As mentioned previously, it is unknown how long it takes for humans to fully acclimate regarding brain metabolism.

These studies indicate the need for more research regarding brain metabolism and function.  Glucose metabolism is crucial for proper functioning of the brain, its neurons, and other regulatory functions. This brings into question what type of impact high altitude may have on the cognitive functions of the brain in people who move or even live at high altitude. Additionally, the fact that the human brain is more prone to injury or developing a concussion, safety should be a consideration for those involved in high impact sports at high altitude.

References

1.      Jaiswal S, Cramer N, Scott J, Meyer C, Xu X, Whiting K, Hoy A, Galdzicki Z, Dardzinski B.  [18F] FDG PET to study the effect of simulated high altitude on regional brain activity in mice. Journal of Nuclear Medicine May 2017, 58 (supplement 1) 1246.  https://jnm.snmjournals.org/content/58/supplement_1/1246

2.      Jaiswal S, Knutsen A, Pan H, Cramer N, Xu X, Dardzinski B, Galdzicki Z, Allison N, Haight T. FDG PET study showing the effect of high altitude and traumatic brain injury on regional glucose uptake in mice.  Journal of Nuclear Medicine May 2019, 60 (supplement 1) 180. https://jnm.snmjournals.org/content/60/supplement_1/180

3.      Hochachka PW, Clark CM, Matheson GO, et al. Effects on regional brain metabolism of high-altitude hypoxia: a study of six US marines. Am J Physiol. 1999;277(1):R314-R319. doi:10.1152/ajpregu.1999.277.1.R314.  https://pubmed.ncbi.nlm.nih.gov/10409288/

Roberta Grabocka is a second-year physician assistant student at Red Rocks Community College’s PA Program in Arvada, Colorado. Roberta attended Stony Brook University in Long Island, NY for her degree in Health Science and received a post-baccalaureate degree in Nuclear Medicine Technology. She practiced for 3 years as a Nuclear Medicine Technologist in multiple hospitals. This included working in oncological, cardiac, and general nuclear settings performing a variety of studies from PET/CTs, myocardial perfusion imaging, HIDAs, V/Qs, etc. Roberta decided to pursue a career as a Physician Assistant to expand her scope of practice and further her medical knowledge. In her free time, she likes to explore local culture and travel.

Return to High Altitude after Recovery from Coronavirus Disease 2019

Andrew M. Luks and Colin K. Grissom

https://www.colorado.com/activities/colorado-hiking

Prior to COVID-19, I would hike the beautiful mountains of Colorado known as 14ers, a name given to these mountains for being over 14,000 ft. I, like most high-altitude travelers faced the more common concerns associated with hiking such as acute mountain sickness (AMS), high altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE). With the increase in high-altitude travel, I wondered if there are any new precautions that we should consider before resuming the activities that we love.

The purpose of this article is to highlight the recommendations for patients who wish to return to high-altitude travel after a COVID infection. Not everyone needs an evaluation after a COVID infection. The recommendations noted in this article are based on the duration and severity of the illness of each individual person.

So, who should receive an evaluation before high-altitude travel?

  1. Individuals with symptoms after 2 weeks of a positive COVID-19 test without hospitalization,
  2. Individuals with symptoms after 2 weeks after hospital discharge,
  3. Anyone who required care in the intensive care unit (ICU), and
  4. Anyone who developed myocarditis or thromboembolic events. The recommendations are to undergo pulse oximetry at rest and with activity, spirometry, lung volumes, and diffusion capacity for carbon monoxide(DLCO), chest imaging, electrocardiography (EKG), B-type natriuretic peptide, high sensitivity cardiac troponin (hsTn), and echocardiography.

It is expected that people with lower oxygen levels (hypoxemia) at rest or with exertion in lower elevations will experience greater hypoxemia with ascent to high altitude. It has been shown that ascent to high altitude causes a decrease in barometric pressure leading to a decrease in ambient and inspired partial pressure of oxygen. The decrease in partial pressure of oxygen in alveoli (PaO2) will trigger vasoconstriction of pulmonary arterioles that slows the rate of oxygen diffusion and activates chemoreceptors that increase minute ventilation from hypoxia. However, it is still unclear whether people with low oxygen levels at low elevations are at greater risk for acute altitude illness after ascent. The recommendation is to monitor pulse oximetry after arrival of high altitude.

Individuals with abnormal lung function tests don’t have to avoid high altitude travel as previous studies have shown that patients with COPD with abnormal lung functions tolerate exposure. Furthermore, in people with mild to severe COVID-19 symptoms, the lung mechanic markers such as forced expiratory volume (FEV1), forced vital capacity (FVC) and total lung capacity (TLC) normalize in up to 150 days of infection.  However, if individuals have severe limitations with exercise capacity, they should monitor their oxygen levels with pulse oximetry after ascent. Reduction in exercise capacity is possible after COVID infection and depends on the severity of the illness. Blokland et al., 2020 has shown that previously intubated individuals had a median VO2 max of 15ml/kg per min (average male 35 to 40 and average female 27 and 30), roughly 57% predicted immediately after hospitalization. 

In acute hypoxia, the heart rate increases, which leads to an increase in cardiac output. Individuals with reduced ventricular function from COVID infection do not have to avoid travel. Previous research has shown that individuals with heart failure can tolerate exercise with hypoxia. Moreover, data has shown that individuals with COVID infection maintain preserved left ventricular function and only 3% show a reduced ejection fraction. Individuals with abnormal EKG rhythms and ischemia should be referred to cardiology.  If high sensitivity troponin was abnormally elevated, this would require evaluation for myocarditis with a cardiac MRI. Knight et al., (2020), found that 45% of patients with unexplained elevations of high-sensitivity troponin were found to have myocarditis during hospitalization. It is still unclear how long these abnormalities will last and how it will affect people.

 A concerning finding on ECHO is pulmonary hypertension, as previous research has shown an increased risk in developing HAPE. A study reported that 10% of patients hospitalized for COVID without mechanical ventilation had right ventricular dysfunction for over 2 months. Several studies reported that 7-10% of individuals may have pulmonary hypertension after COVID infection. A vasodilating drug such as nifedipine can be given prophylactically if pulmonary hypertension is unrelated to left heart dysfunction but nifedipine can worsen hypoxemia.

The recommendation for patients who developed myocarditis from a COVID infection is to have an ECHO, Holter monitor, and exercise EKG 3-6 months after illness. Travel can resume after a normal ECHO, no arrhythmias on exercise EKG, and after inflammatory markers (ESR and/or CRP) have normalized. Previous studies suspected that areas with low atmospheric pressures (e.g., high-altitude) that induce hypoxia have increased risk for clot formation. However, this suspicion has never been firmly established; therefore there is no reason to believe that high-altitude will increase the risk for clot formation in individuals who developed an arterial or venous clot from COVID infection.

A few things to consider before planning a high-altitude excursion includes planning to visit areas with access to medical resources or the ability to descend rapidly. If you are new to high altitude, it is recommended to slow the ascent rate. Traveling to high elevations (>4000m) should be avoided until tolerance has developed with moderate elevations (2000-3000m). A more gradual return to physical activity at high altitude is recommended rather than immediate resumption of heavy exertion. As the pandemic subsides and with increase in mountain travel, more research will develop that can better address these risks.

Good news! The Ebert Family Clinic in Frisco, CO provides pulse oximeters for free. So, make sure to visit and grab your pulse oximeter before your next ascent.

Quick Summary of Recommendations

Individuals who require evaluation prior to high-altitude travel:

  1. Individuals who have symptoms after 2 weeks of a positive COVID-19 test without hospitalization
  2. Individuals who have symptoms after 2 weeks after hospital discharge
  3. Any patient who required care in the intensive care unit (ICU)
  4. Any patient who developed myocarditis or thromboembolic events

General recommendations for anyone before high-altitude travel:

  1. Monitor pulse oximetry after arrival of high altitude, and access care or descend if symptoms worsen.
  2. Rest and avoid high-altitude travel for at least 2 weeks after a positive test, and consider a gradually return to physical activity at higher altitudes.
  3. All individuals planning high-altitude travel should be counseled on how to recognize, prevent, and treat the primary forms of acute altitude illness (AMS, HACE, and HAPE)
  4. Limit the extent of planned exertion after ascent and, instead, engage in graded increases in activity that allow the individual to assess performance and avoid overextending themselves.

Reasons to forgo high-altitude travel:

  1. Severely elevated pulmonary artery pressures may be a reason to forego high-altitude travel altogether.
  2. High-altitude travel should likely be avoided while active inflammation is present in myocarditis.
  3. Patients who experienced arterial thromboembolic events due to COVID-19, (e.g. myocardial infarction or stroke) should defer return to high altitude for several months after that event or any associated revascularization procedures.

References:

  1. Andrew M. Luks and Colin K. Grissom. Return to High Altitude After Recovery from Coronavirus Disease 2019. High Altitude Medicine & Biology. http://doi.org/10.1089/ham.2021.0049
  2. Christensen CC, Ryg M, Refvem OK, Skjønsberg OH. Development of severe hypoxaemia in chronic obstructive pulmonary disease patients at 2,438 m (8,000 ft) altitude. Eur Respir J. 2000 Apr;15(4):635-9. doi: 10.1183/09031936.00.15463500. PMID: 10780752.
  3. Blokland IJ, Ilbrink S, Houdijk H, Dijkstra JW, van Bennekom CAM, Fickert R, de Lijster R, Groot FP. Inspanningscapaciteit na beademing vanwege covid-19 [Exercise capacity after mechanical ventilation because of COVID-19: Cardiopulmonary exercise tests in clinical rehabilitation]. Ned Tijdschr Geneeskd. 2020 Oct 29;164:D5253. Dutch. PMID: 33331718.
Image of Jesse Santana, dark brown hair, brown skin, beard and moustache with a stethoscope draped over his white coat, striped, collared shirt and maroon tie.

Jesse Santana is a second-year PA student at Red Rocks Community College in Denver, Colorado. He grew up in Colorado Springs, CO and attended the University of Colorado-Colorado Springs where he earned a bachelor’s in Biology and Psychology. Jesse worked as a Certified Nursing Assistant for two years before pursuing a Master’s in Biomedical Sciences at Regis University in Denver. Shortly after, he coordinated clinical trials in endocrinology and weight loss as a Clinical Research Coordinator at University of Colorado Anschutz Medical Campus. He enjoys hiking Colorado’s 14ers, spending time with family and friends, and camping.

Anxiety at Altitude

As I arrived in Denver (5280′), and ultimately Frisco, CO (9000′), the first physical symptom I noticed from the high-altitude environment was dyspnea on exertion. On flat ground I didn’t feel any different than at home in New Jersey, but as soon as I began to climb stairs or hike the beautiful trails in the area, I quickly became winded. I had already read about the common symptoms of high-altitude acclimation and knew this was normal and was on the lookout for headache, nausea, or dizziness. I noticed my resting heart rate was elevated and told myself this was also normal because the low-oxygen environment required my heart to work harder to keep my pulse oxygen levels up. I already owned a pulse oximeter that I had bought during my time working with COVID patients in the Emergency Room on a previous rotation. I checked that within my first week and was initially disappointed that it was averaging around 91%, but soon found out this was also normal, especially since I was still acclimating. My Apple watch trended data over time on my heart rate and I noticed a tremendous difference in my resting HR compared to home.

I landed on May 2nd, 2021 and I think the graphs above make that quite evident. My walking HR was even more noticeably elevated. “The initial cardiovascular response to altitude is characterized by an increase in cardiac output with tachycardia … after a few days of acclimatization, cardiac output returns to normal, but heart rate remains increased”1

My persistently elevated heart rate caused me to feel anxious when hiking or doing other physical activity, and that anxiety in turn raised my heart rate even more. I had experienced PVC’s in the past which occurred only a few times a month, nowhere near the threshold for treatment, and had been reassured they were totally benign. On a hike during my first week in Colorado I experienced a few of these “skipped beats” followed by rapid heart rate and had to talk myself down from the anxiety it caused. This is what prompted me to research the effect of altitude on anxiety. “Adrenergic centers in the medulla are activated in acute hypoxia and augment the adrenergic drive to the organs.”2 It seems as though the body’s compensatory mechanisms to physiological changes can be accompanied by unwanted mental health disturbances. This is especially true for people in the early stages of shifting from low altitude to high altitude. During the adjustment period individuals are most susceptible to new-onset anxiety disorders, but even those living long-term at high altitude are at increased risk of psychiatric ailments.4 In fact, living in high-altitude environments has been associated with serious mental health implications not limited to anxiety disorders, including depression and increased suicidality.4 This has been evidenced by statistically significant changes in PHQ-9 Total Score, PHQ-9 suicidal ideation, and GAD-7 Total Score.4

Sleep disturbances have often been faulted for these increases in anxiety and depression at high altitude, and although I didn’t have any formal sleep studies done while in Colorado, I felt well-rested and didn’t notice a change in my sleep at altitude.3 One hypothesis that could explain these findings and my personal experience, is that hypoxia has an inverse relationship with serotonin.4 Because oxygen is a requirement for the creation of serotonin, living somewhere with decreased oxygen could lead to deficiency. Serotonin has an expansive role in the human body, playing a role in cognition, sleep, mood, digestion and other crucial aspects of life. Low levels of this neurotransmitter have been implicated as a cause for depression and accordingly many of our best antidepressant medications like SSRI’s and SNRI’s work on these pathways. There is also a “chicken or the egg?” argument to be made. Is the anxiety brought on due to hypoxia which in turn causes somatic symptoms like palpitations, shortness of breath, and presyncope; or do these symptoms caused by hypoxia come first, resulting in anxiety and panic attacks? For example, hyperventilation, a well-known provocative factor of panic attacks, is also a response to altitude changes. Hypoxia leads to hypocapnia, which can ultimately lead to respiratory alkalosis.5 Although there are multiple hypotheses for these mental health changes, there does seem to be an agreement in the literature that they do exist.

Luckily, in my experience, my body adjusted over the span of a few weeks. My HR began to trend down towards my normal resting rate in the 70’s and my anxiety levels also dropped. I started doing more challenging hikes, traveling and enjoying the many natural wonders Colorado has to offer. Just being in amazing places like Rocky Mountain National Park and the San Isabel National Forest had a profound impact on my mood as I soaked in the scenery. I took pictures, breathed fresh mountain air and spotted wildlife, which all served to distract me from my worries. The mood-altering benefits of exercise also likely played a role in my increasing happiness. I grew to love the state and as soon as I felt fully adjusted, it was time to go back to New Jersey. Back to sea-level, outrageous humidity and hotter weather.

References:

  1. Naeije R. Physiological adaptation of the cardiovascular system to high altitude. Prog Cardiovasc Dis. 2010 May-Jun;52(6):456-66. doi: 10.1016/j.pcad.2010.03.004. PMID: 20417339.
  2. Richalet JP. Physiological and Clinical Implications of Adrenergic Pathways at High Altitude. Adv Exp Med Biol. 2016;903:343-56. doi: 10.1007/978-1-4899-7678-9_23. PMID: 27343107.
  3. Bian SZ, Zhang L, Jin J, Zhang JH, Li QN, Yu J, Chen JF, Yu SY, Zhao XH, Qin J, Huang L. The onset of sleep disturbances and their associations with anxiety after acute high-altitude exposure at 3700 m. Transl Psychiatry. 2019 Jul 22;9(1):175. doi: 10.1038/s41398-019-0510-x. PMID: 31332159; PMCID: PMC6646382.
  4. Kious BM, Bakian A, Zhao J, Mickey B, Guille C, Renshaw P, Sen S. Altitude and risk of depression and anxiety: findings from the intern health study. Int Rev Psychiatry. 2019 Nov-Dec;31(7-8):637-645. doi: 10.1080/09540261.2019.1586324. Epub 2019 May 14. PMID: 31084447.
  5. Roth WT, Gomolla A, Meuret AE, Alpers GW, Handke EM, Wilhelm FH. High altitudes, anxiety, and panic attacks: is there a relationship? Depress Anxiety. 2002;16(2):51-8. doi: 10.1002/da.10059. PMID: 12219335.

Joseph Albanese is a second-year physician associate (PA) student attending Drexel University in Philadelphia, Pennsylvania. He grew up in Hillsborough, NJ. He got his BA from The Pennsylvania State University as a double major in Psychology and Film Studies. Prior to PA school he worked as a mental health associate in an inpatient psychiatry setting with actively suicidal and homicidal patients. The acuity of the unit he worked on made him appreciate the benefits of talk-therapy, but also the crucial role of medicine in many cases. This led him to apply to PA school. In his free time Joe loves to travel (favorite places include Japan, Iceland, Glacier National Park, and now Colorado). He also enjoys photography, playing sports, and eating new foods.