Often, at high altitude we hear complaints of gas pain and increased flatus in our infant population. Parents often wonder, are we doing something wrong? Is my child reacting to breastmilk, or showing an intolerance to certain foods? Actually there is another explanation for increased flatus and gas pain in the high-altitude region of Colorado.
The term HAFE was coined by Dr. Paul Auerbach and Dr. York Miller and published in the Western Journal of Medicine in 1981. Their discovery began In the summer of 1980, when the two doctors were hiking in the San Juan Mountains of Colorado on a quest to summit three 14ers. During their ascent they noticed that something didn’t smell right! As the pair continued to emit noxious fumes, they began to put their scientific brains to work and discovered HAFE. The symptoms include an increase in frequency and volume of flatus, or in other terms an increase in toots! We all have familiarity in watching our bag of potato chips blow up when reaching altitude or our water bottle expanding as we head into the mountains. This reaction is due to a decrease in barometric pressure. Based on Boyle’s law, decreased barometric pressure causes the intestinal gas volume to expand, thus causing HAFE (Skinner & Rawal, 2019).
To my surprise, a gas bubble the size of a walnut in Denver, Colorado (5280 ft) would be the size of a grapefruit in the mountain region of Summit County, CO (8000+ ft)! Trapped gas is known to lead to discomfort and pain. The use of simethicone may have merit in mitigating the effects of HAFE. Simethicone works by changing the surface tension of gas bubbles, allowing easier elimination of gas. This medication, while benign, can be found over the counter and does not appear to be absorbed by the GI tract (Ingold, C. J., & Akhondi, H., 2022).
While this phenomenon may not be as debilitating as high-altitude pulmonary edema (HAPE), it deserves recognition, as it can cause a significant inconvenience and discomfort to those it inflicts. As the Radiolab podcast explained in their episode The Flight Before Christmas , expelled gas in a plane or car when driving up to the mountains can be embarrassing. While HAFE can be inconvenient, it is a benign condition and a matter of pressure changes rather than a disease or pathological process. We would love to talk more about HAFE at Ebert Family Clinic if you have any questions or concerns!
A bald eagle flies toward its nest atop a bare lodgepole pine.
As always, stay happy, safe, and healthy 😊
Taylor Hollingsworth is finishing her final semester as a family nurse practitioner (FNP) student at Georgetown University. Originally from the east coast, Taylor plans to start her FNP career in North Carolina close to family. She has a passion for pediatric and family wellness and has worked as a pediatric intensive care unit nurse for 6 years! In her free time, Taylor loves to hike, fly fish, run, and spend time with her fiancé Logan.
References
Auerbach, P. & Miller, Y. (1981). High altitude flatus expulsion. The Western Journal of Medicine, 134(2), 173-174.
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.
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.
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.
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.
I had the honor of interviewing Andrew Breithaupt who recently retired from US Customs and Border Protection in the Department of Homeland Security where he served as an Air Interdiction Agent piloting multiple types of aircraft. He currently serves as a Lieutenant Colonel on active duty for the US Army, stationed in Minneapolis, MN. He began Army flight school in 1992 to become a helicopter pilot, ultimately qualifying in 4 different types of Army helicopters including the UH-1H, OH-58, AH-1, and the AH-64 Apache for which he became an Instructor Pilot training new Army aviators at Fort Rucker, Alabama. Later he began his transition to fixed-wing aircraft in the civilian community. After nearly 10 years of Army active duty and multiple overseas tours, he was selected to enter service for US Customs and Border Protection where he served as a federal law enforcement agent for over 20 years, retired in December of 2021. He holds his commercial pilot license for single engine & multi-engine fixed wing as well as rotorcraft with instrument privileges and aircraft type ratings. He has over 30 years of aviation experience and more than 2,500 hours of flight time over his career. I sat down to chat with him about his accomplished career and learn more about his aviation and altitude expertise.
In army flight school, specifically aeromedical training, he was taught the effects of aviation on the body. One of the first lessons they learned in their training was how to recognize the early warning signs of hypoxia. These include shortness of breath, dysphoria, nausea, vomiting and lightheadedness. This type of training is often done in altitude chambers, so trainees can experience these effects before they are in the air, including how aviation can affect your vestibular senses. A position change as simple as looking down to change a radio or instrument can completely disorient a pilot due to the change in direction of the fluid within the inner ear against the cilia. This can lead to the sensation that the plane has rotated and flying sideways. They are taught to trust their instruments because an overcorrection can lead to what they teach in flight school as a “death spiral.” The training is often done in a Barany Chair and simulates vestibular senses experienced during flight.
Elevation in Summit County, Colorado ranges from 7,947 feet to 14,270 feet, the highest peak being Gray’s Peak. With people living as high as 11,200 feet, as Andrew does at his home in Blue River located south of of Breckenridge, CO. Andrew shared some very interesting aviation altitude requirements which might surprise some. He spent much of his career operating non-pressurized helicopters and Federal Aviation Regulations prohibited him from going between 10,000 feet to 12,000 feet for more than 30 minutes without oxygen. When flying above 12,000 feet, pilots are required to have supplemental oxygen regardless of the amount of time spent at that elevation depending on the category of aviation being conducted such as commercial operations. This is according to the CFR (Code of Federal Regulations) Part 135 which governs commercial aircraft operations. How interesting is it that pilots have these regulations, yet many people who live in Summit County or those summiting 14ers (peaks at 14,000 ft. or above) are at or above these elevations with no supplemental oxygen on a daily basis. When flying private aircraft, CFR part 91.211 specifies flight crew can fly without pressurization or supplemental O2 below 14,000 feet and passengers below 15,000 feet.
While in the Army, Andrew would rarely operate aircraft above 8,000 feet and would typically not have supplemental oxygen on board. They were trained to begin descent immediately if they were to notice the early signs of hypoxia. Keeping a pilot’s license requires strict annual or even semi-annual FAA physicals and continued training to ensure their bodies can withstand the effects of aviation. As you can imagine those holding these licenses are some of the most fit men and women in the country. Andrew rarely felt the effects of altitude even with altitude changes as great as 8,000 feet coming from sea level. He would typically remain at these elevations for two hours or less piloting non-pressurized aircraft.
To give some perspective, when you hop on a commercial flight for your next adventure these planes typically fly around 28,000 to 36,000 feet of elevation. When beginning the ascent, the aircraft pressure stabilizes at 6,000 to 8,000 feet, approximately when the dreaded “popping of the ears” is felt. Supplemental oxygen and quick donning masks are required on all these aircraft in case depressurization were to occur due to the rapid hypoxia which would occur at such high altitudes.
Andrew moved to Summit County in November of 2021 from Stafford, VA with his wife and five sons ages 24, 22, 19, 14, and 11. Andrew and his family spent a significant amount of time in Summit County for snowboarding and skiing competitions and quickly fell in love with the area prior to spending the last 5 years living in Stuttgart, Germany. This is when they decided one day, they would become full-time residents of the county. They moved here for the “people, climate and lifestyle,” a combination I am learning is hard to beat outside of Summit County. With ski and snowboard season right around the corner, he and his family are excited to get back out on the slopes. Andrew currently travels between his home in Blue River and Minneapolis for his position in the Army. With each trip back he feels his body more quickly adjust to the altitude changes. Thank you for your service Andrew, and welcome to the community!
Ellie Martini grew up in Richmond, VA and is currently a second-year Physician Assistant student at Drexel University in Philadelphia, PA. She completed her undergraduate degree at The College of William and Mary in Williamsburg, VA where she received her BS in Biology. Before PA school she worked as a rehab tech and medical scribe at an addiction clinic. In her free time she enjoys hiking, biking, group fitness, traveling and spending time with friends and family.
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
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
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 his father-in-law arrived in the mountains, Thomas noticed later that night he seemed intoxicated despite not seeing him drink alcohol. Thomas woke up the next morning to see him reading the paper in nothing but black socks and a black tie. Thomas knew right away he wasn’t drunk, he had high altitude cerebral edema (HACE). HACE is a complication of acute mountain sickness (AMS). HACE can occur from increased pressure in the blood vessels in the brain, leading to fluid leakage and swelling (edema). This increased vessel pressure can result from the lower atmospheric pressure at high altitude1. Breathing in lower atmospheric pressure gives you less oxygen molecules per breath. Thomas estimates that EMS in Summit County see one case of HACE a year. EMS look for two hallmark signs of HACE, altered mentation and ataxia. When EMS arrive to a patient with altered mentation, they have the patient walk heel-to-toe to evaluate for ataxia. If ataxia is present, immediate descent is necessary. Rapid descent is necessary because HACE can progress rapidly. Years ago, Thomas had a patient walk into the emergency department and die within 10 minutes after arrival. Unlike high altitude pulmonary edema (HAPE), descent is the only cure for HACE.
HAPE is a more common complication of AMS. Similar to HACE, edema occurs from the high pressure inside pulmonary blood vessels pushing fluid into the lungs. The high pressure is caused by a rapid vasoconstriction response to hypoxia or low oxygen partial pressures. Luckily, HAPE has a simple treatment, oxygen. Therefore, visitors with HAPE do not need to descend to lower altitude as with HACE. HAPE is much harder to recognize than HACE and EMS is well trained in how to recognize it. Often, headache is the only symptom2. Thomas explains the HAPE protocol for EMS: In the first 20 seconds of arriving, an oxygen saturation is obtained; they obtain vitals in the next two minutes and then start high flow oxygen if the saturation is below 89%; they then listen to the lungs for signs of fluid. EMS does not treat HACE or HAPE with any medications since descent and oxygen are the effective treatments.
So, who is prone to AMS?
Unfortunately, better physical fitness does not protect you from AMS. Thomas reports that athletes with resting heart rates of 40 or below have a difficult time acclimating. Younger age also doesn’t mean easier acclimation. According to Thomas, the best age for acclimation is late 30s/early 40s. Surprisingly, previous hypoxia can help acclimation to high altitude. For example, Thomas reports that smokers have an easier time acclimating because their body is used to having the vasoconstriction response to hypoxia and breathing faster and deeper to get adequate oxygen intake.
But don’t worry, your conditioning wasn’t for nothing. A healthy diet and regular exercise prevents heart disease. Thomas estimates there are about 12 acute MI’s on the ski hill each year. These patients usually have to be transported to Denver for a stent to be placed. Exacerbation of coronary artery disease (CAD) is so common that EMS refers to altitude travel as the “altitude stress test.” This mimics a cardiac stress test in those with CAD, producing chest pain that wasn’t present at lower altitude.
Those with sickle cell disease are at risk of developing sickle cell crisis when traveling to high altitude. The lower atmospheric pressure allows the normal red blood cells to lose their integrity and become sickle. Thomas reports that EMS encounters this every couple months in patients (usually of Mediterranean descent) that present with diffuse abdominal pain with no obvious cause. This pain results from the sickle cells aggregating together and causing an occlusion. The occlusion leads to tissue hypoxia and ischemia3. These patients are transported to the hospital for treatment.
How can mountain tourists avoid AMS?
Thomas’s first recommendation is to take a staggered stop for one night at an elevation of 5,000-6,000ft, like Denver. When arriving to altitude, take it easy the first 3 days: don’t drink alcohol and do light activity. Save the long hike for the end of the trip. Also avoid substances that blunt the respiratory system like alcohol, opioids, benzodiazepines, etc. Prepare by hydrating the week before and keep drinking plenty of water while on the trip. If you have had a previous episode of AMS, you can speak to your medical provider about prophylactic medication to take before arriving at high altitude.
2. Schafermeyer, R. W. DynaMed. Acute Altitude Illnesses. EBSCO Information Services. https://www.dynamed.com/condition/acute-altitude-illnesses. Accessed November 19, 2021.
3. Sheehan VA, Gordeuk VR, Kutlar A. Disorders of Hemoglobin Structure: Sickle Cell Anemia and Related Abnormalities. In: Kaushansky K, Prchal JT, Burns LJ, Lichtman MA, Levi M, Linch DC. eds. Williams Hematology, 10e. McGraw Hill; 2021. Accessed November 23, 2021. https://accessmedicine-mhmedical-com.ezproxy2.library.drexel.edu/content.aspx?bookid=2962§ionid=252529206
Samantha Fredrickson is currently a student in Drexel University’s Physician Assistant program.
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?
Individuals with symptoms after 2 weeks of a positive COVID-19 test without hospitalization,
Individuals with symptoms after 2 weeks after hospital discharge,
Anyone who required care in the intensive care unit (ICU), and
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:
Individuals who have symptoms after 2 weeks of a positive COVID-19 test without hospitalization
Individuals who have symptoms after 2 weeks after hospital discharge
Any patient who required care in the intensive care unit (ICU)
Any patient who developed myocarditis or thromboembolic events
General recommendations for anyone before high-altitude travel:
Monitor pulse oximetry after arrival of high altitude, and access care or descend if symptoms worsen.
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.
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)
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:
Severely elevated pulmonary artery pressures may be a reason to forego high-altitude travel altogether.
High-altitude travel should likely be avoided while active inflammation is present in myocarditis.
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:
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
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.
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.
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.
As someone with family history of cardiac illness and a personal history of both supraventricular tachycardia (SVT) and high blood pressure, I have always tried to manage my modifiable risk factors through a healthy diet and exercise. Over the past year or two, most of my exercise has been in the form of running, since it is more conducive to the schedule of a physician assistant student during COVID restrictions. However, in the past I have been a regular rock climber and soccer player. Through my own personal experience I have noticed that when I stick to a healthy diet, not giving in to my sweet tooth, and keeping up with regular exercise that my episodes of SVT are less frequent. However, recently I traveled up from Denver, Colorado for a rotation at the Ebert Family Clinic in the mountain town of Frisco, and in the first two days at high elevation experienced an episode of SVT for the first time in nearly 6 months.
In my first day at over 9000 feet, I experienced a slight headache after a full day seeing patients, but did not think much of it or even consider it to be a side effect of the altitude. I spent my first day at altitude without exercising but I decided that on day two I had acclimated enough to go for a short run. Midway into my run, and shorter of breath than I expected, I experienced an episode of SVT that lasted for about 2-3 minutes and forced me to sit for several more minutes to catch my breath. Catching my breath afterward took slightly longer compared to my normal episodes, which made sense to me given the reduced availability of oxygen, but it did lead me to wonder if the altitude was a contributing factor to precipitating an episode of SVT after several months without one.
About one year ago, High Altitude Health interviewed Dr. Peter Lemis, a cardiologist in Summit County, Colorado about his thoughts and findings practicing cardiology at elevation. The discussion included questions about arrhythmias at altitude and Dr. Lemis stated that “studies have shown that cardiac arrhythmias are increased initially, but people become acclimated after about 3-5 days and the risk returns to baseline”. However, Dr. Lemis also states that the studies may not have been conducted for a sufficient length of time due to his personal experience of seeing a great deal of both atrial fibrillation and atrial flutter in his own practice. He states that the hypoxia leads to an increase in arrhythmias, but that for atrial arrhythmias, patients may experience relief from them when placed on nocturnal oxygen. Dr. Lemis also notes that “many people have central apnea during sleep at altitude due to the brain’s blunted response to high CO2 and low O2”, which can be a risk factor for the development of heart problems. The use of Diamox can be helpful in acclimating to altitude due to making “your blood a little acidotic which increases your respiratory drive” and the use of nocturnal oxygen can also help with acclimatization to altitude.
In March of 2021, the journal of Frontiers in Medicine published an article titled Nocturnal Heart Rate and Cardiac Repolarization in Lowlanders with Chronic Obstructive Pulmonary Disease at High Altitude: Data from a Randomized, Placebo-Controlled Trial of Nocturnal Oxygen Therapy by Maya Bisang, Tsogyal Latshang, Sayaka Aeschbacher, et al. This study compared COPD patients at altitude with and without oxygen therapy at night and COPD patients not at altitude without oxygen looking at QT interval, heart rate, and SpO2. The results of the study found that without oxygen use at altitude patients experienced an increase in heart rate, a lengthened QT interval, and naturally, a lower SpO2 at night compared to those at altitude who utilized oxygen and those that were not at elevation. This study was observing patients that had COPD. The results could potentially be relevant to younger patients without COPD, like myself, but would need further research.
I also looked into information regarding high blood pressure at altitude and found some helpful information from the Institute for Altitude Medicine. They state that for patients visiting altitude with a history of hypertension (HTN), even if it is well controlled on pharmacotherapy, may still experience a temporary increase in blood pressure at altitude. “One explanation for this is due to the higher levels of adrenaline or stress hormones in your body due to lower oxygen levels,” as they describe. Their research has also found that increases in blood pressure at altitude generally return to base line after 1-2 weeks. In order to help manage HTN at altitude they recommend ensuring that blood pressure is well controlled at sea level, reducing salt from the diet, remaining on any medications for HTN, checking blood pressure at altitude, and observing for symptoms of HTN that would need medical care such as headache, dizziness, chest pain, or shortness of breath.
Through my research regarding effects of altitude and the possible role of them in my recent episode of SVT, I have found that altitude can have several different impacts on cardiac function that definitely could have played a role in triggering an episode. Coming to altitude, I likely had an increase in blood pressure to compensate for the reduced availability of oxygen that increased strain on my cardiac muscle. I may have had EKG changes overnight related to decreased responsiveness of my central nervous system to CO2 levels. I also had an increased risk of arrhythmia based on coming to elevation. It is possible that any or all of these effects could have contributed or triggered my episode of SVT. Thankfully, after almost a month of staying at altitude I have adjusted more and have not experienced another episode. I have continued to exercise after a short break to allow more time to acclimate, but I have not pushed myself as hard.
I have learned that no matter how healthy you are or what your risk factors are, there are important steps to stay healthy when coming to altitude. If possible, at least one day at an intermediate altitude can help your body begin to adjust to the change. Drinking plenty of water to stay hydrated and avoiding alcohol can lead to a more comfortable stay and more rapid acclimatization. Meeting with a healthcare provider could also allow you to start a prophylactic course of Diamox or supplemental oxygen use. Utilizing a personal pulse oximeter allows you to monitor your SpO2 level and determine if nocturnal supplemental oxygen could be useful as well. If you have risks for cardiac conditions or already have a diagnosis of heart disease, these recommendations are even more important to prevent poor outcomes including myocardial infarctions due to reduced oxygen availability. Finally, it is important to remember that traveling to altitude is not a benign choice and a discussion with your healthcare provider is important to be sure that your personal risks are appropriately managed so that you can enjoy your trip to high elevation.
Justin Frazier is currently in his second year of PA school at Red Rocks Community College in Arvada, CO, a member of the class of 2021 graduating in November. He attended Appalachian State University in Boone, NC for his undergraduate degree majoring in Cell and Molecular Biology with a double minor in Chemistry and Medical Humanities. During his undergraduate he worked for two and a half years as a CNA at a local nursing and rehabilitation facility. After completing his undergraduate degree he started working as an EMT for almost a year before transitioning to work in a family medicine office where he worked as a Medical Assistant until starting PA school. He enjoys working in a primary care setting where he can help to keep people healthy throughout their lives and wants to pursue a career in pediatrics after graduating this year. He enjoys hiking, camping, rock climbing, and spending time with his wife and young son.
According to recent research, nearly thirty million individuals in the United states have been diagnosed with diabetes. Due to this higher rate of prevalence, more people are aware of the basic information surrounding a diabetic diagnosis. However, there are common misconceptions surrounding the average diabetic patient, with most information focused on the more common form of diabetes, type 2. Although the majority of diabetic patients in the United states do have type 2 diabetes, an estimated 5 to 10% of people with diabetes actually have type 1. Type 1 diabetes is an autoimmune disease in which the body’s own immune system destroys the cells in the pancreas that make insulin. Insulin is a very important hormone that enables sugar to enter the bloodstream in order for it to be used by the cells for energy, as well as stored for later use. Unlike type 2 diabetes, there is no cure for type 1 diabetes and the treatment options are limited; the only management for this form of diabetes is insulin therapy. The most common therapeutic regimens for type 1 diabetes includes constant monitoring of blood sugars using a glucometer or continuous glucose device. These devices combined with either syringes, preloaded insulin pens, and/or an insulin pump are the means to survival for type 1 diabetics. However, there have been many advancements in the ways physicians are able to help their type 1 diabetics control and manage their disease. Because of this, type 1 diabetics are able to live their lives with far less complications. When desired, type 1 diabetics are able to compete at high levels of activity and complete amazing feats, such as wilderness activities.
It is inspiring to know how type 1 diabetics are still able to perform in high intensity activities such as ultramarathons, ironmen/ironwomen, as well as professional sports, to name a few. However, with such strenuous activity, it is important to note that diabetes control is more challenging. Of note, it cannot be stressed enough, that baseline diabetic control is already challenging in itself. By adding the addition of a strenuous environment and activity, diabetes control becomes more difficult as it is multifactorial.
To help address this issue, the Wilderness Medical Society (WMS) worked to form clinical practice guidelines for wilderness athletes with diabetes. The WMS gathered a group of experts in wilderness medicine endocrinology, primary care, and emergency medicine to compose these guidelines. These guidelines are outlined for both type 1 and 2 diabetics who participate in mild-vigorous intensity events in wilderness environment with reduced medical access and altitudes greater than or equal to 8250ft; the objective to help individuals with diabetes better plan and execute their wilderness goals. The foundation summarizes their recommendations into pre-trip preparation, including a list of essential items to bring when on your wilderness trip, potential effects of high altitude on blood glucose control and diabetes management, and an organized algorithm to treat hyperglycemia and ketosis in the backcountry.
Effects of High Altitude on Diabetes Management:
At baseline, the various types of exercise activities are broken into aerobic, anaerobic, and high intensity exercise. Each type of exercise utilizes the energy stored in our bodies, in the form of sugar. In a healthy person without any comorbidities, during aerobic activities, glucose uptake into the large muscle groups is increased due to the increase in energy expenditure. To keep glucose higher during this form of exercise, insulin secretion is reduced. Simultaneously, other hormones such as adrenaline, cortisol, and glucagon are released into the system to promote further glucose release from processes such as gluconeogenesis and glycogenolysis.
Again, the body is utilizing its resource of glucose to move to the larger muscle groups to keep them moving and active. During anerobic and high intensity exercise, the same process occurs, but since these forms of exercise tend to be in short bursts, insulin levels tend to rise particularly in the post workout period. This helps to diminish the effects of the counterregulatory hormones and keep blood sugar levels stable. If the athlete is unable to properly regulate insulin secretions during these various forms of exercise, then it is likely that he/she will experience frequent episodes of hyperglycemia. Also, due to the increase in insulin sensitivity in muscles post workouts lasting >60 min, hypoglycemia can also ensue.
In general, the WMS and other research demonstrates brief episodes of high intensity exercise are linked to hyperglycemia for diabetics. On the other hand, longer duration aerobic exercise will cause hypoglycemia. Unfortunately, due to the complex intricacies of glycemic control during exercise, in addition to the individuality of each patient and the multiple variables involved in each wilderness expedition (temperature, altitude, duration, etc.), the definitive guidance for adjustment of daily insulin continues to need refinement. This is why the WMS recommends extensive pre-trip planning with the various tools, research, and supplies that will be needed when planning any form of wilderness adventure.
Pre-trip Prep:
Like all endeavors, preparation is key in order to be better equipped to deal with the majority of future scenarios. Planning is especially important when going on a wilderness expedition. Preparation becomes even more important with the diagnosis of diabetes. The WMS outlines the specific recommendations that should be included as a diabetic wilderness athlete. For example, pre-trip prep should generally include: (1) a medical screening, (2) research of the endeavor and how it may affect glucose management, and lastly (3) essential diabetes-specific medical supplies and backups.
Additionally, according to the American diabetes association, persons with diabetes should discuss with their primary care provider and or endocrinologist before a strenuous wilderness activity. This follow up ensures that athletes are up to date on their screenings, health maintenance labs, and prescriptions needed for therapy. Due to the various ways that diabetes can affect the body, the WMS also recommends that if a patient has cardiovascular involvement, retinopathy, neuropathy, or nephropathy, there should be a more extensive risk assessment by the provider. Although these complications are less commonly seen in high intensity wilderness athletes, adequate histories should be taken to avoid adverse circumstances.
As discussed earlier, altitude accompanied with increased strenuous exercise demands also has various effects on blood glucose management. As it pertains to altitude and blood sugar management in type 1 diabetes, multiple studies have shown an increase in insulin requirements at altitudes above 4000m (13,123′). At this time, researchers are unsure if this finding is due to the effects of acute mountain sickness or hypobaric hypoxia. Therefore, wilderness athletes with diabetes should be aware of the insulin resistance increase at these extreme altitudes. In conjunction with altitude changes, as previously noted, the type of exercise will also play a role in insulin control. Aerobic exercise for longer than 60 minutes can cause a hypoglycemic episode in type 1 diabetics due to the increased muscle sensitization to insulin. Therefore, at altitudes 4000m or above, wilderness athletes will be in a mixed long duration anaerobic/aerobic exercise. With the combination of these factors, there is a counter regulation effect, and the athlete becomes both more sensitive to insulin due to increase duration of exercise and less sensitive due to altitude demands. In order to better predict the effects of altitude combined with exercise, the WMS recommends close monitoring on shorter trips to recognize their specific glycemic trends prior to an extreme high-altitude expedition, as well as increased close monitoring of glucose management during their high-altitude endeavors.
Table 1: Environmental Effects on Diabetes, Imported from WMS
Lastly, in preparation of a high-altitude excursion, there are recommended items that should be packed for daily management of glucose, in addition to back up items to ensure athletes with diabetes aren’t left in a dangerous situation. Fortunately, the WMS was able to create a well-organized table on the recommended supplies.
Table 2: Medical Kit Preparation, Imported from WMS
Treatment of ketoacidosis or HHS:
To be properly prepared, an athlete should complete his/her own research on how changes of altitude and exercise can affect blood glucose management. This includes complete pre-trip preparation and packing. Once cleared, a diabetic athlete can finally head out on the high-altitude adventure. In case of emergency, a diabetic should be aware of the proper steps if he/she were to experience diabetic ketoacidosis (DKA), hyperosmolar hyperglycemic state (HHS), or even acute mountain sickness (AMS). Hyperglycemia is described as a blood glucose greater than 250 mg/dL and without adequate treatment can lead to either DKA or HHS. Type 1 diabetics are more likely to go into DKA, while type 2 diabetics are more inclined to present in HHS. One of the most important indicators if a person were to be in DKA are ketones in blood or urine. This is why it is very important to make sure a wilderness athlete carries ketone strips in his/her emergency medical pack. Typically, if a patient finds ketones in their urine after using a ketone strip, then he/she is educated to seek emergent medical attention. When on a wilderness adventure, this can be a difficult task to accomplish. This is why the WMS also developed a flowchart in order to manage hyperglycemia and DKA without medical support. Refer to table 3 for their flowchart.
Table 3: Algorithm for management of hyperglycemia and ketosis in the backcountry. EDD, estimated daily dose, PO, oral intake, Imported from WMS
One issue that diabetics have when dealing with high-altitude is differentiating hypoglycemia and hyperglycemia side effects from AMS. The most reliable differentiating factor is increased blood sugar readings correlating with symptoms. WMS states that either a continuous glucose monitor or increased finger sticks for a higher frequency of blood sugar readings is important to determine if a person with diabetes is experiencing blood sugar complications of AMS. When discussing treatment of AMS in diabetics, the same methods are used as are recommended for a non-diabetic individual: Acetazolamide and dexamethasone in initial medical management. In regard to diabetes, it is important to discuss the potential additional side effects. Acetazolamide can worsen dehydration and acidosis if used at the wrong time. Dexamethasone is known to worsen blood glucose control. Both are still useful in acute mountain sickness but must be weighed against causing worsened complications.
Conclusion:
When participating in a wilderness adventure, individuals with diabetes will be prone to more medical side effects. Changes in altitude, along with the level of activity are known to affect diabetic control, so proper preparation prior to departure is required in order to ensure the health and safety of a diabetic wilderness athlete. After being cleared by a medical professional and obtaining proper information, diabetics can plan to complete a wilderness adventure similar to that of a healthy individual with no comorbidities. However, it is common for diabetics to experience hyperglycemia with high intensity activities and an increase in altitude. Therefore, diabetics (particularly type 1 diabetics), should be prepared with extra insulin to counteract elevated glucose levels. Alternatively, if a diabetic were to be at higher altitude with a longer duration of aerobic or anaerobic exercise, then he/she may be prone to hypoglycemia — lower blood sugar levels. In either case, individuals with diabetes will need to monitor blood sugar levels more closely. The WMS provides diabetics with an outline of recommended supplies that may be needed in the wilderness. The outline also suggests for diabetics to bring ketone strips, as this is the most accurate measurement to determine if a diabetic is in DKA or HHS. The ultimate goal of the WMS is to ensure the health and safety of diabetic athletes. Diabetes is a difficult disease to manage but becomes even more challenging when partaking in a wilderness adventure.
(All tables and figures imported from WMS)
References:
de Mol P, de Vries ST, de Koning EJ, Gans RO, Tack CJ, Bilo HJ. Increased insulin requirements during exercise at very high altitude in type 1 diabetes. Diabetes Care. 2011;34(3):591-595. doi:10.2337/dc10-2015
VanBaak KD, Nally LM, Finigan RT, et al. Wilderness Medical Society Clinical Practice Guidelines for Diabetes Management. Wilderness Environ Med. 2019;30(4S):S121-S140. doi:10.1016/j.wem.2019.10.003
Jonathan Edmunds is a second-year physician assistant student at RRCC PA Program in Arvada Colorado. Jonathan is a Colorado native, born and raised in Littleton, CO. He attended Colorado State University in Fort Collins, CO where he competed in Track and Field as a long jump/triple jumper, as well as earned his bachelor’s Biological Sciences. During his junior year in college, he was diagnosed with Type 1 diabetes and quickly became an advocate the support of diabetes education. After graduating in 2015, he focused his medical career aspirations on becoming a PA. He volunteered at Banner Fort Collins Medical Center and work at Bonfils Blood Center as a phlebotomist for 2 years before applying to PA school. In his free time, he enjoys coaching track and field at Littleton high school his alma mater, doing all things outdoors, and cozying up to his three “Irish” chihuahuas at home.
As a California native, I was unfamiliar with the impact high altitude had on the human body. I had only briefly learned about it in my exercise physiology course during my undergraduate studies. At best, I understood the difference between acclimation and acclimatization, and the advantages of living at high altitude for exercise performance. What I never really understood was how much all that information would mean to me when the next chapter in my life took me to Colorado.
In hindsight, I did everything against the book after moving to Colorado because I wanted to stay active and enjoy as much as I could before school started. I continued my daily workout routines, went whitewater rafting, and had a few drinks. More importantly, I was not hydrating adequately because I didn’t know you could drink straight from the tap. So… what happened? The end of my workout routines was met with dizziness and lightheadedness. On some occasions, I would notice my fingertips turn purple. My sleep would be interrupted by episodes of apnea. Though these symptoms did resolve eventually, they could have been prevented if I had followed a few simple rules.
As a student at Ebert Family Clinic in Frisco, CO at 9000′ alongside high altitude expert Dr. Christine Ebert-Santos, I had the opportunity to learn more about high altitude illness, interviewing Dr. Gustavo Zubieta-Calleja and his daughter Dr. Natalia Zubieta-Urioste from the High Altitude Pulmonary and Pathology Institute (IPPA) in La Paz, Bolivia. Dr. Zubieta has been practicing internal medicine and pulmonology at his father’s high altitude clinic since 1981. During our interview, we discussed their most recent publication Acute Mountain Sickness, High Altitude Pulmonary Edema, and High-Altitude Cerebral Edema: A view from the High Andes. When asked about what inspired him to follow his father’s footsteps, he replied, “My father created the first high altitude clinic in the world and that was a great inspiration to me. He did it with a visionary idea because at the time in 1970, nobody thought about putting a clinic like that out. I was born at home because my father was a physician and he preferred to deliver us. We [me and my siblings] were all delivered at home and then that home became the clinic in 1970. The clinic turned 50 this past year and our father also became our mentor at this clinic.”
The article addresses the two types of adaptation: genetic and physiologic. In his publication, he primarily addresses the physiologic mechanisms that must occur for one to adapt to the hypobaric environment that is high altitude. During my research, however, I found that Tibetans experienced the fastest phenotypically observable evolution in human history partially because their community has spent centuries living at that altitude. When I discussed my findings with Dr. Zubieta, he stated that much still needs to be done to determine if the Andean population has made similar genetic adaptations. He was optimistic about the studies to come as he strongly believes that all organisms must adapt if they want to survive and reproduce at high altitude. According to Dr. Zubieta, change is inevitable. He believes that the energy expenditure from the body’s initial response to the hypobaric environment is too costly forcing the human body to adapt in a manner that will render it more effective in managing this energy expenditure via metabolism at the mitochondrial level.
We also discussed the different attitudes towards the use of acetazolamide, or Diamox. In the United States, acetazolamide is a diuretic commonly used to prevent the onset of acute mountain sickness. Dr. Ebert Santos highly recommends the use of acetazolamide to prevent acute mountain sickness while Dr. Zubieta and other providers reluctantly use it due to the risk of dehydration. A 125-milligram dose is adequate and unlikely to cause side effects, which Dr. Zubieta said can include fatigue, nausea, vomiting, abdominal pain, and diarrhea. (Most visitors to Colorado taking acetazolamide only experience tingling of the hands and feet and a flat taste to carbonated beverages.) Dr. Zubieta justifies his avoidance of acetazolamide as an “opportunity” to treat the patient’s underlying issues, stating that ascension to high altitude is a testament of one’s cardiovascular fitness and the use of acetazolamide compromises adaptation to high altitude. At the IPPA they have uncovered underlying conditions that explain their patients’ symptoms at altitude and resulted in better health upon returning to sea level.
The Wilderness Medical Society has established a risk stratification for acute mountain sickness which further supports Dr. Zubieta’s infrequent use of acetazolamide. The society’s 2019 guidelines suggest that individuals with no history of altitude illness and ascending to an elevation no greater than 2,800 meters, and individuals who take more than two days to arrive at an altitude between 2,500 and 3,000 meters are considered low risk and the use of acetazolamide is not recommended. Instead, Dr. Zubieta recommends Ibuprofen and Acetaminophen for headache relief and oxygen in those with persistent symptoms of acute mountain sickness. He also emphasizes that oral hydration can be important in preventing high altitude illnesses.
Overall, Dr. Zubieta’s perspective on high altitude is fascinating. During my master’s program, I learned a systematic way to treat patients using guidelines or criteria backed by years of evidence that helps you, the provider, make an informed decision on a patient’s particular case. Dr. Zubieta reinforced the importance of treating each patient’s case individually to determine the underlying cause, rather than suggesting acetazolamide to everyone who doesn’t want to deal with acute mountain sickness. As for myself, seeing how physicians in other countries approach certain illnesses has definitely made me think twice about how to approach high altitude illness.
To learn more about Dr. Gustavo Zubieta and his clinic, you can visit his website at: https://altitudeclinic.com/
Born and raised in Northern Orange County of California, Michael Le is a second-year physician assistant student at the Red Rocks Community College Physician Assistant Program in Arvada, CO. Michael attended California State Polytechnic University Pomona otherwise known locally as Cal Poly Pomona where he earned his bachelor’s degree in Kinesiology. Shortly after, he worked as an EMT for Lifeline Ambulance, and physical therapy aide and post-anesthesia care unit technician at Fountain Valley Regional Hospital in Fountain Valley, CA. In his free time, Michael likes to cook and breed show rabbits.
