The Mitochondrial advantage at altitude

Dr. Deborah Liptzen, pediatric pulmonologist from Children’s Hospital of Colorado,

Presents a talk on high altitude to the Ebert Family Clinic staff

I learned several new facts about adaptation to altitude that make us better athletes. First, our muscles have more capillaries to deliver blood to the cells. Second,  the cells have more mitochondria which are organelles involved in the chemistry of respiration and energy production.

Other ways our bodies respond to altitude include: increased breathing rate (instant), increased red blood cells (peaks in three months), hemoglobin in red cells holds on to more oxygen, and blood vessels in the lungs constrict (immediate).It is this constriction of blood vessels in the lungs that can go haywire putting pressure on the capillaries causing fluid leaks that lead to pulmonary edema or HAPE.

Rethinking Your Energy Supply

On May 27th 2017, Adrian Ballinger summited Mount Everest without supplemental oxygen. This is an accomplishment that less than 200 people have achieved and followed a failure to summit the previous May of 2016. The 41 year old seasoned climber attributed his failures to the cold, which could have been aided by more muscle and fat content, better insulated jacket and gloves, but he wondered why his climbing partner, Cory Richards so easily made it to the top. Ballinger came to realize it that wasn’t his gear or body composition, but it was that Richards had a different approach to training and nutrition that gave him the edge to summit. Richards trained with a organization called Uphill Athlete that trains its athletes to become a fat burners. After hearing of Richard’s training regimen Ballinger was determined to pursue the same for a another summit attempt in 2017. Ballinger was a carb burner, which means he was relying on burning carbohydrates for energy. When he attempted to summit Everest being a carb-burner, he simply ran out of energy to fuel his body through the last grueling stretch. This was due to depleted glycogen levels that a carb-burner relies on. The average human can only contain enough carbohydrates to supply glycogen stores for about 45 minutes. Once your glycogen stores are depleted, you need to refuel, which in Ballinger’s case, would mean pulling a hand out of a mit in the frigid Everest air to replenish his energy every 45 minutes. This is also known as “bunking,” which means completely exhausting your energy supply, which is what happened to Ballinger. Richards on the other hand, was a fat burner. With alterations in Ballinger’s nutrition and training regimen, he was successful in 2017.

But what is a fat burner?

A fat burner is an athlete that primarily uses fat for energy, and this metabolic process is called fat oxidation. When an athlete is exercising on a typical high carb and low fat diet, they are burning about a 50/50 mix of carbs and fats during steady exercise. If that athlete decides to sprint at full speed being a carb burner or a fat burner, they are primarily burning carbohydrates, known as glycogen. This is the body’s evolutionary design to have instant energy to run away from the tiger when it storms your cave. In Ballinger’s scenario, the high intensity of Everest climbing was like a sprint, depleting all of his glycogen stores causing him to “bunk”.

Why is a fat-burning diet better for climbing?

Being a fat burner for a long distance endurance athlete is beneficial because it eliminates the need to refuel every 45 minutes, which is bothersome. Ever wonder why there is a plethora of fancy sugary “sports” drinks, gummies, and energy bars at sporting stores? They are called “energy” foods, because they are loaded with simple carbohydrates and sugar. On the other hand, a fat burner does not need refueling foods or drinks during exercise, but relies on the extensive supply of fat throughout the body. Even the most elite athletes with very low body fat will have enough to supply the body energy for a event. Picture this, there is a giant fuel tanker truck cruising on I-70. The truck has its own fuel tank which sits below the cab of the truck, which will be depleted in a couple hours. What if the truck could access the large tank that it’s hauling? That would give the trucker a enough fuel to drive for days! In the context of nutrition and your body, the small tank is the your glycogen storage and the large tank is fat storage. This is why some people can fast for days without skipping a beat; they have tapped into their fat supply.

What does it take to become a fat burner?

To become a fat burner, it’s quite simple: cut the carbohydrates. Well, I guess some may think it’s not so easy. You have to cut out pizza, bread, candy, tortillas, and all that good tasty stuff. When a person limits their carbohydrate intake to less than 10% of caloric intake, and increase fat consumption to 70% of their intake, their body shifts into a different mode of creating energy, by burning fat instead of carbs. The by-products of fat oxidation are called ketones. When a person converts to being a fat burner, it is called being in ketosis. This process may take a few days to weeks, which varies from person to person.

Is there any research behind this crazy idea of eating all the bacon and butter you can handle? ….Yes, yes there is!  

In the research article by Volek et al. (2015), the authors wanted compare a low carbohydrate ketogenic diet and a typical high carbohydrate diet in 20 elite endurance athletes. The authors tested the athletes with a 180 minute, moderate intensity (64% VO2 max), treadmill run.

VO2 max is known as the capacity of your cardiovascular system and its ability to distribute oxygen throughout the body. Higher means a stronger cardiovascular system, so 64% of your maximum effort would be considered moderate exercise.

A 64% VO2 max to you or I would be a brisk walk or a slow hike up the that beautiful 14’er, but for these Ironman athletes it was a easy run on a treadmill. The authors compared the rate of fat oxidation and carb oxidation between the two diets, as well as their ability to recover and replenish their glycogen stores. The authors found that the fat adapted athletes had 2.7 times the rate of fat oxidation than the high carb diet athletes. The low carb group also had fat oxidation at higher VO2 max, meaning they could go faster without tapping into their precious glycogen stores. The study also found that after the exercise, the athletes in both groups had similar glycogen level in their muscle. This is significant because the classic rule of thumb with exercising is that you need t a post-work shake with protein and carbs to replenish your muscles, or your exercising efforts are gone to waste…WRONG! It turns out your body has its own way of replenishing its glycogen stores without the post workout carb load. That means after you climb that 14’er, you don’t necessarily have to stop at the local brewery for carb-tastic IPA, but I don’t judge you if you do.

In another research article by Hetlelid et al., they wanted to compare the levels of fat and carb oxidation levels between nine well-trained (WT) runners and nine recreationally-trained (RT) runners during a high-intensity interval training session (HIIT). There was no difference in diets amongst the participants is the study. The study found that the WT runners had a three times higher rate of fat oxidation than RT runners and increased performance with higher VO2 max. The author attributed the increased performance due to the higher rates of fat oxidation. These athletes were consuming a normal carb-ful diet, which makes me wonder what the difference would have been if they were fat adapted.  

So, let’s get down to why all this mumbo jumbo is important to your next trip to the high country. Many outdoor activities that we enjoy in the summer like hiking, biking, climbing, etc. all require significant energy to supply for all day fun. Take climbing a 14’er for example. You will most likely be climbing for several hours, depleting your energy stores as you climb being on a high carb diet. You have to stop, refuel, start up climbing, stop and repeat. As a fat adapted climber, you could sail past your carb-comrades with ease, not depleting your glycogen stores all day, all while burning some of that winter Christmas cookie belly in the process. As we examined the two research articles, we also found that higher fat oxidation could mean higher VO2 max levels. What does this mean for your next trip to high altitude? That’s right, better usage of the less available oxygen level in the high country and improving oxygen delivery throughout the body. If you want to be the best Balliger you can be on the mountains this summer, rethink your energy supply and consider life in the fat lane! 

So, here are some personal tips to becoming fat adapted…

-Give you body at least 3 weeks to become adapted before any highly strenuous activity, climbing a 14’er

-Hydrate, hydrate, hydrate with water and balanced with electrolytes

-Consult with your physician before drastically changing your diet

-Choose foods high in natural fats (eggs, nuts, olive oils, avocados, meat, fish, dairy) stay away from unhealthy trans fats

-Intermittent fasting can help you transition into ketosis faster (12-16 hrs)

 

Hetlelid, K. J., Plews, D. J., Herold, E., Laursen, P. B., & Seiler, S. (2015). Rethinking the role of fat oxidation: Substrate utilisation during high-intensity interval training in well-trained and recreationally trained runners. BMJ Open Sport & Exercise Medicine, 1(1). doi:10.1136/bmjsem-2015-000047

Volek, J. S., Freidenreich, D. J., Saenz, C., Kunces, L. J., Creighton, B. C., Bartley, J. M., . . . Phinney, S. D. (2016). Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, 65(3), 100-110. doi:10.1016/j.metabol.2015.10.028

http://www.adrianballinger.com/about/

Altitude research partnership with University of Heidelberg and University of California in San Diego

Two of the most prominent centers for altitude research in the world are University of Heidelberg, led by Peter Bartsch MD and                                                                                                               University of California in San Diego, with John West MD.

Dr Christine Ebert-Santos met with five of their affiliated researchers while in San Diego where she presented her case on                                                                                                                    trauma and HAPE at the American Thoracic Society conference.

They are interested in partnering with Ebert Family Clinic for a study related

to the genetics of high altitude, using our area as an intermediate altitude location.

Photo of Dr. Chris with UCSD staff  Tatum Simonson PhD, facing, Jeremy Orr MD, behind her,

Jeremy Sieker MD PhD candidate from Colorado, and University of Heidelberg staff  Heimo Mairbaurl PhD and Christina Eichstaedt PhD

Mountains and Caffeine

Effects of Caffeine at High Altitude

Visitors travelling to high altitude destinations have been known to avoid coffee/caffeine intake in order to avoid the dreaded symptoms of acute mountain sickness. The theory is that caffeine leads to dehydration, which then predisposes the individual to acute mountain sickness. A few symptoms of dehydration include headache, lethargy, confusion, weakness and nausea and vomiting. Similarly, symptoms of acute mountain sickness include fatigue, headache, nausea, vomiting, shortness of breath and difficulty sleeping. Although the symptoms of dehydration and acute mountain sickness are very similar, there is no evidence to support this claim that dehydration predisposes an individual to acute mountain sickness.1 Thus, the diuretic effect of coffee and caffeine are often exaggerated. Individuals that are accustomed to drinking 12 oz. of coffee rarely suffer from the diuretic effect of the beverage.1 (See Table 1).

Table 1. Caffeine content (mg) per serving in various foods, drinks and medications.

The condition of acute mountain sickness is a response to hypoxia in the brain’s vascular circulation that causes an increase in the release of a neurotransmitter called adenosine. Adenosine binds to adenosine receptors found on the inner lining of cerebral blood vessels, causing vasodilation of the blood vessels in an attempt to increase the flow of oxygen and nutrient rich blood to the brain. This increase in cerebral blood flow, however, is painful and causes many of the above-mentioned symptoms of acute mountain sickness.

Caffeine, in contrast, counteracts these effects of adenosine in the brain’s circulation by causing vasoconstriction of those cerebral blood vessels, decreasing blood flow within the brain. Therefore, it is likely that caffeine can help prevent the onset of acute mountain sickness because of its ability to decrease cerebral vasodilation in response to hypoxia at high altitude.1 Caffeine is included in several over-the-counter headache medications, such as Excedrin Migraine, exactly for this purpose.

While there is no clinical data exhibiting that caffeine increases the rate at which individuals acclimate to living at high altitude from sea level, physiologic studies suggest that caffeine is helpful in increasing ventilation and decreasing hypoxia. Caffeine stimulates chemoreceptors in the brain and carotid arteries, altering the brainstem’s respiratory center in the medulla oblongata to become more sensitive to low blood oxygen saturation. As a result of this increased sensitivity to hypoxia, the lungs and respiratory muscles unconsciously increase their activity to increase resting ventilation rate and increase blood oxygen saturation.

My Experience

During my six weeks at the Ebert Family Clinic for my pediatric medicine rotation, I measured my blood oxygen levels before and after drinking 12 oz of coffee. My results can be found in Table 2.

Table 2. Six-week average blood oxygen saturation pre- and post-consumption of 12 oz. coffee

Pre-coffee oxygen saturation average: Post-coffee oxygen saturation average:

 

Week 1 91% 94%
Week 2 90% 92%
Week 3 91% 93%
Week 4 92% 94%
Week 5 92% 93%
Week 6 91% 93%

While these results are an anecdotal summary of my own experience living at high altitude and drinking coffee for six-weeks, drinking 12 oz. of coffee showed an average increase of blood oxygenation of 2%.

Caffeine Study at Everest

One study conducted at the base camp of Mt. Everest (17,600 ft) studied the 24-hour effect of caffeine in black tea ingested by one study group compared to a placebo group that only drank water. Both groups ingested the same volumes of liquid in the 24 hours. The study found that both groups had identical urine amounts at the end of the study, suggesting that caffeine did not lead to dehydration. Additionally, the tea-drinking group reported less fatigue and better mood compared to the placebo group.1

Caffeine Withdrawal at High Altitude

Caffeine cessation in fear of dehydration while travelling to high altitude destinations often leads to an exacerbated withdrawal reaction from caffeine, mimicking the symptoms of acute mountain sickness. This is due to the up-regulation, of adenosine receptors in the brain that become uninhibited in the absence of caffeine. As a result, adenosine binds to the increased amount of adenosine receptors in the brain causing excessive cerebral vasodilation and subsequent headache, nausea, vomiting, weakness, lethargy and confusion. Therefore, regular coffee drinkers or any type of caffeine users should avoid abrupt cessation of caffeine intake while traveling from sea level to high altitude.1

Future Studies

The above mentioned studies have not studied the effects of caffeine in caffeine-tolerant vs. caffeine-naïve individuals, but a trial of caffeine in the form of either coffee, tea or pill would be worthwhile in otherwise healthy individuals suffering from symptoms of acute mountain sickness while visiting high altitude locations. Future studies would benefit from comparing the effects of caffeine on caffeine tolerant individuals and individuals who do not consume caffeine on a regular basis. However, individuals must always consult their health care provider to determine if it is safe to use caffeine prior to consumption of caffeine products.

Michael Peterson, PA-S

University of St. Francis, Physician Assistant Program

It’s so exciting to be CITED!

Today I opened the March 2018 issue of the Journal of High Altitude Medicine and Biology.

What a surprise!

My publication  was cited in an article on pulmonary edema in children written by professors in the pulmonary department at Children’s Hospital of Colorado!  This is actually the first indication I’ve had that anyone beside me believes in the entity I called Mountain resident HAPE in the article published in the same journal last September.

Dr. Liptzin and her colleagues wrote, “We briefly describe high-altitude illnesses and propose recommendations for evaluation and treatment of HAPE in children as well as investigate the underlying contributors to HAPE. We discuss high-altitude resident pulmonary edema (HARPE), a new entity (Ebert-Santos, 2017). We will also highlight areas for further research.” The authors do not recommend prophylactic treatment for HAPE. Rather they recommend that when symptoms develop, supplemental oxygen be applied and  descent to lower altitude.

Summit v.s. Saipan: Running

Dr. Chris and Jacqueline, her niece from Guam, enjoy the Beach Road rec path in Saipan

When I lived on Saipan in the Pacific and visited my parents in Breckenridge I noted that my 10k  times were just as good at 9000 ft with humidity around 27% and temperatures in the 70’s as at sea level with 80% humidity and temperatures in the 80’s. Last month I had the same experience, in reverse: living at high altitude and visiting Saipan. Reading our blog on asthma, I attribute that to the lower viscosity of air and lower air pressure in the mountains compared to the high density of water vapor in the islands.  Both locations are beautiful and inspiring places to run!

Pediatrics Gun Storage Practices

The American Academy of Pediatrics published a new study titled “Firearm Storage in Homes with Children with Self-Harm Risk Factors.” The conclusion of this article was that parent’s decision to have firearms in the home as well as their storage practices were not influenced by the presence of a child with a mental health condition in the home. The study was comprised of a web-based survey, which was completed by parents of 3,949 households in the US. The results showed that approximately 42% of households that contained children confirmed having a firearm in the house. This percentage did not change when comparing household in which children with mental health reside to those whose children had no mental health issues. The study also showed that of those parents/ caregivers who own firearms only 1 in 3 stored all firearms locked and unloaded. This ratio did differ between households that contained children with mental health issues versus those that did not.

This study led me to question the role of pediatrics in determining the ownership and storage of firearms in homes with children. At every well child visit for children above a certain age we ask if there are any firearms in the house and if so, how are they stored. I found myself wondering “Have studies shown a decrease in injury by firearms following pediatrician intervention and education?” A study published in 2000 concluded that “a single firearm safety counseling session during well child care combined with economic incentives to purchase safe storage devices, did not lead to changes in household gun ownership and did not lead to statistically significant overall changes in storage patterns.” However a randomized controlled trial published more recently, in 2008, concluded that a brief office-based violence prevention approach resulted in increased safe firearm storage.

The American Academy of Pediatrics first issued guidelines in 1992 noting that the safest home for a child is one without firearms. These guidelines also note that if firearms are going to be in households they should be locked and unloaded with ammunition stored separately. I grew up in a house of avid hunters and gun owners and I can just hear them saying, “What good is a gun in the case of an intruder if it is not immediately accessible?” One study in the Journal of Trauma found that “guns kept in homes are more likely to be involved in a fatal or nonfatal accidental shooting, criminal assault, or suicide attempt than to be used to injure or kill in self-defense.” This article claims that the benefit of having a gun in the house for self-defense does not outweigh the risk of accidental injury by that same “protective” weapon. Other’s who advocate for firearm use and ownership claim that if children are properly educated and trained in gun safety there would be less accidental shootings. However, one study published in 2002 had children participate in a weeklong firearm safety program on reducing children’s play with firearms. Following this training period the children were exposed to an unloaded firearm. 53% of the children played with the gun as if it was a toy gun. This study cast doubt on the effectiveness of skills-based gun safety programs for children.

I recognize that it would be naïve of me to think that every gun owner with children in the house is going to forfeit his or her right to their firearms because of this data. That is why there are important organizations such as Project Childsafe (http://www.projectchildsafe.org/parents-and-gun-owners) that cater towards gun owners. This organization provides comprehensive information about gun safety in the home and offers free resources such as cable-style gunlocks to further protect children in their homes.

Jocelyn Rathbone PA-S

References:
Scott J, Azrael D, Miller M. Firearm Storage in Homes With Children With Self-Harm Risk Factors. Pediatrics 2018 March; 141(3): e20172600. Retrieved March 11, 2018.
Kellermann AL, Somes G, Rivara FP, Lee RK, Banton JG. Injuries and deaths due to firearms in the home. J Trauma. 1998 Aug; 45(2):263-267. Retrieved March 11, 2018.
Barkin SL, Finch SA, Ip EH, Scheindlin B, Craig JA, Steffes J, Weiley V, Slora E, Altman D, Wasserman RC. Is office-based counseling about media use, timeouts, and firearm storage effective? Results from a cluster-randomized, controlled trial. Pediatrics. 2008; 122(1): e15. Retrieved March 11, 2018.
Grossman DC, Cummings P, Koepsell TD, Marshall J, D’Ambrosio L, Thompson RS, Mack C. Firearm safety counseling in primary care pediatrics: a randomized,  controlled trial. Pediatrics. 2000; 106(1 Pt1): 22. Retrieved March 11, 2018.
Hardy MS. Teaching firearm safety to children: a failure of a program. J Dev Behav Pediatr. 2002;23(2):71. Retrieved March 11, 2018.
Gill AC, Wesson DE. Firearm Injuries in Children: Prevention. UptoDate. Literature review current through Feb 2018. Last updated March 14, 2018. Retrieved March 11, 2018.

Tatum Simonson and Altitude Adaption: Physiologic and Genetic

Tatum Simonson is a researcher at the University of California, San Diego who is interested in high altitude medicine: specifically, how high altitude adaptations can, over hundreds of generations, become part of our genes. I read one of her publications called Altitude Adaptation: A Glimpse Through Various Lenses. It delves into the research that has been done on physiologic and genomic changes of high altitude inhabitants and how these two factors coincide.

When looking at this information, it is important to remember that the reason high altitude is so much different from sea level or lower altitude is the oxygen in the air. It is not necessarily the percentage of the oxygen in the air, because the air is 20.9% oxygen at all altitudes. It is actually the lower air pressure that makes it feel like there is less oxygen. The air pressure comes from the weight of the air above us in the atmosphere. The further you go up, the less atmosphere there is above you to press down, and therefore less air pressure. Boyle’s law (whoa physics!) basically says that because of the lower pressure, in a given volume of air there are fewer molecules. Because there are fewer molecules of everything, the percentage of oxygen remains 20.9% but it feels like there is less oxygen in the air.

This is all to say that organisms have to adapt to this lower air pressure and less molecules in a given volume. Things that we know are affected include the saturation of oxygen of our blood. With less air pressure to drive the saturation of our blood with oxygen, sometimes it leads to low oxygen levels, or hypoxia. Hypoxia is detrimental because our body needs oxygen for our cells to function.

Simonson looks at 3 populations that have lived at high altitudes (3500m-4500m or 11,483ft-14,764ft) for hundreds of generations: Qinghai-Tibetan Plateau, Andean Altiplano, and Semien Plateau of Ethiopia (see map below). In her paper she goes further into the history of these populations and the uncertainty that exists with their timeline, but for our purposes just know that these populations have inhabited these high altitude areas for anywhere from 5,000-70,000 years.

Figure 1. Map with three locations where high-altitude adapted populations have lived for hundreds of generations. (Image modified from http://www.nasa.gov/topics/earth/features/20090629.html; low elevations are purple, medium elevations are greens and yellows, and high elevations are orangered and white.) Tatum S. Simonson. High Alt Med Biol. 2015 Jun 1;16(2):125-137.

The first lens she looks through is physiologic, or how the body functions. There has been extensive research in this lens, summarized below.

  • Increased common iliac blood flow into uterine arteries in Tibetan and Andeans leads to increased utero-placental oxygen delivery at altitude, allowing less growth restriction. In other words, Tibetan and Andean populations have increased the blood flow to the growing fetus to help it grow more like someone living at lower altitudes. Furthermore, some studies show that their babies are actually bigger.
  • Tibetan and Amhara Ethiopian populations show the characteristic increase in hemoglobin levels that has long been associated with travelers to high altitude, but to a much lower extent than someone who has just traveled to altitude (i.e. native lowlander). This is in contrast even with Andean populations, who have higher hemoglobin levels than Tibetans. The Tibetan and Amhara Ethiopian populations don’t necessarily need a higher level of hemoglobin (molecule that carries oxygen) to get the oxygen that they need to their tissues.
  • Differences in the control of breathing: the hypoxic ventilation response is an increase in ventilation that is induced by low oxygen levels. The research shows that Tibetans exhibit an elevated hypoxic ventilation response while Andeans exhibit a blunted response.
  • Tibetan and Sherpa have been shown to have higher heart rates than lowlanders at altitude, as well as increased cardiac output, or blood that they are able to pump out of their hearts. There are also differences in the energy sources that some high altitude populations use for their heart to pump.
  • There are certain adaptive changes in skeletal muscle that Sherpa populations have made as well. Specifically, increased small blood vessels and increased maximal oxygen consumption.

The second lens is genomic, or the evidence for different genes in highlanders that have allowed them to survive and thrive at higher altitudes. One theory is that the ancestors of modern day highlanders had specific genes that gave them traits that were favorable for surviving at high altitudes. By matter of Darwinian selection, these genetic variants were passed down favorably over generations.

  • Many genes studies are involved in the hypoxia-inducible factor (HIF) pathway, which is involved in regulating various responses to hypoxia including making new blood vessels, making new red blood cells, iron regulation, and metabolism.
  • Specific genes studied include EPAS1has been associated with low (within sea level range rather than elevated) hemoglobin in Tibetans at altitude discussed above. EGLN1 and PPARA have also been associated with hemoglobin concentration changes.
  • There are many other specific genes that have been associated with specific adaptive changes for these high altitude populations.

It is important to realize the physiologic and genetic components of adaptation to high altitude environment. Simonson sums it up best herself:

“Understanding the associations between genetic and physiological variation in highlanders has additional application for understanding maladaptive and general responses to hypoxia, which remain an important biomedical component of hypoxia research. This is also of clinical value when considering distinct and shared hypoxia-associated genetic variants and combinations thereof may contribute to physiological responses in residents and visitors to the environmental hypoxia at altitude as well as chronic…or intermittent…states of hypoxia.

I was happy to read this article and see how high altitude medicine may be affected by genomics in the not-so-distant future. Hopefully you learned something about hypoxia, physiologic and genetic adaptations!

Hannah Evans-Hamer, MD

 

Resources:

Simonson T. Altitude Adaptation: A Glimpse Through Various Lenses. High Alt Med Biol. 2015 Jun; 16(2):125-37. PMID: 26070057; PMCID: PMC4490743.

 

 

 

Trauma Related High-Altitude Pulmonary Edema

HAPE Poster

Dr. Chris will be presenting this poster at the American Thoracic Society International Conference in San Diego in May of this year! This is an exciting opportunity that will spread knowledge of high altitude medicine with the leading researchers in the field. In addition, she hopes to have this case study published to raise awareness among other healthcare providers practicing at any altitude about the potential health complications associated with rapid changes in elevation.

Katie Newton, PA-S
University of St. Francis
Albuquerque, NM

 

Reentry High Altitude Pulmonary Edema (HAPE) in High Altitude Residents!

When High Altitude Pulmonary Edema (HAPE) is diagnosed, one often thinks of the diagnosis in relation to patients who have lived long term in low/sea level altitudes coming to high altitudes for the first time. However, a new study conducted by Santosh Baniya based out of the Himalayas suggest there is a subset of HAPE in which long term high altitude residents can fall ill to HAPE upon reentry to high altitudes after even a brief stay at lower altitudes.

Baniya’s study is based off a case report of an otherwise healthy pediatric patient who was diagnosed with HAPE after returning to his village of Manag (3500m) after a winter in Besisahar (760m)- a trip that was done multiple times in his life time with no complications. One change surrounding this diagnosis was a recent construction of a road between the two villages that decreased the usual travel time from a span of several days to a single day. The pathophysiologic explanation behind this phenomenon is thought to be caused by the descent of high altitude residents to lower altitudes, leading to a decrease in the red cell mass and a compensatory rise in plasma volume, which then in turn predisposes an individual to pulmonary edema once they return to high altitudes. Had the patient taken the original route of travel- it is likely that the gradual ascent would’ve allowed his body to acclimate to the altitude change and the red cell mass and plasma levels would’ve adjusted accordingly. However, due to the decrease in overall travel time the excess plasma levels led to pulmonary edema. Manifestation of this included shortness of breath, respiratory distress, and hypoxia (an oxygen saturation of 44% in this case). Treatment included high-flow oxygen, dexamethasone to help with air way swelling, and descent to lower altitudes which resulted in immediate marked improvement.

The remarkable aspect of this case- and the reason it was published- is that the doctors in a high altitude community failed to recognize a condition familiar to medical providers in the mountains here in Colorado. More importantly the clinical symptoms that we describe here are also pertinent to Mountain Resident HAPE and Trauma Related HAPE, which is often misdiagnosed by experts in Denver and other lower altitude communities outside of Colorado. Understanding the prevalence of this phenomenon is of utmost importance as an incorrect diagnosis of influenza, pneumonia or asthma could lead to fatal consequences- as oxygen does not treat these conditions. Proper recognition, diagnosis and treatment with oxygen, rest, and if severe enough, descent into lower altitudes need to be carried out promptly for effective treatment.

 

Garkie Zhu, PA-S3
MCPHS PA Program

Reference:

Baniya, S. (2017). Reentry High Altitude Pulmonary Edema in the Himalayas. High Altitude Medicine & Biology,18(4), 425-427. Retrieved January 23, 2018.

Ebert-Santos, C. (2017). High-Altitude Pulmonary Edema in Mountain Community Residents. HIGH ALTITUDE MEDICINE & BIOLOGY, 18(3), 278-284. Retrieved February 2, 2018.