Health care providers and people who live at altitude often believe that living in the mountains protects from altitude related illness. And yes, there are many ways the body acclimatizes over days, weeks, months, and years, as addressed in previous blog entries. However, as a physician who has practiced in high altitude communities for over 20 years, my personal observation that we are still at risk for serious complications was reenforced by a recent publication by Dr. Santiago Ucrós at the Universidad de los Andes School of Medicine in Santa Fe de Bogotá, Colombia. His article, High altitude pulmonary edema in children: a systemic review, was published in the journal Pediatric Pulmonology in August 2022. He included 35 studies reporting 210 cases, ages 0-18 years, from 12 countries.
Consistent with our experience in Colorado, the most common ages were 6-10 years and second most common 11-15 years. I have not seen or read any reports of adults affected. Cases included two deaths, which I have also seen here.
I receive reports on any of my patients seen in urgent or emergency care. Accidents, avalanches, and suicide attempts are what we think of first needing emergency care in the mountains. However, the most common critical condition is Reentry HAPE. This is a form of pulmonary edema that can occur in children who are returning from a trip to lower altitude. Think visiting Grandma during school break. Dr. Ucrós’ review also confirms that all presentations of HAPE (classic, as in visitors, reentry, and HARPE, resident children with no history of recent travel) are more common in males by a 2.6 to 1 ratio. Analysis of time spent at lower altitude before the episode showed a range of 1.6 to 30 days with a mean of 11.3 days. Mean time between arrival and onset of symptoms for all types of HAPE was 16.7 hours. The minimum altitude change reported in a HAPE case was 520 meters (1700 feet), which is the difference between Frisco, CO (Summit County) and Kremmling, CO (Grand County, the next county over). A new form of HAPE in high altitude residents who travel to higher altitude was designated HL-HAPE in this review. A case report will be featured in an upcoming blog interview with a Summit County resident who traveled to Mt. Kilimanjaro.
As with all cases of HAPE, the victims develop a cough, sound congested as the fluid builds up in their lungs, have fatigue, exercise intolerance, with rapid onset over hours of exposure to altitude, usually above 8000 ft or 2500m. Oxygen saturations in this paper ranged from 55 to 79%. My patients have been as low at 39% in the emergency room. Children presenting earlier or with milder cases come to the office with oxygen saturations in the 80’s. An underlying infection such as a cold or influenza is nearly always present and considered a contributing factor. Everyone living or visiting altitude should have an inexpensive pulse oximeter which can measure oxygen on a finger. Access to oxygen and immediate treatment for values under 89 can be life-saving.
The recurrence rate for all types of HAPE is about 20%. Most children never have another episode, but some have multiple. Preventive measures include slower return to altitude, such as a night in Denver, acetazolamide prescription taken two days before and two days after, and using oxygen for 24-48 hours on arrival. Most families learn to anticipate, prevent, or treat early and don’t need to see a health care provider after the first episode.
On January 26, 2023 I met with Dr. Ucrós and other high altitude scientists including Dr. Christina Eichstaedt, genetics expert at the University of Heidelberg in Germany, Dr. Deborah Liptzen, pediatric pulmonologist, and Dr. Dunbar Ivy, pediatric cardiologist, both from the University of Colorado and Children’s Hospital of Colorado, and Jose Antonio Castro-Rodríguez MD, PhD from the Pontifica Universidad Católica in Santiago de Chile.
We discussed possible genetic susceptibility to HAPE and hypoxia in newborns at altitude with plans to conduct studies in Bogotá and Summit County, Colorado.
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.
It took ten years for me to convince high altitude experts that children living in the mountains get high altitude pulmonary edema (HAPE) without leaving home. My observations were published in 2017 in the Journal of High Altitude Medicine and Biology,
High-Altitude Pulmonary Edema in Mountain Community Residents
This week Dr. Jose A Castro-Rodriguez MD PhD ATSF discussed HAPE in children at the 8th World Hypoxia conference in La Paz including the now renamed high altitude resident pulmonary edema (HARPE) in his presentation.
Dr. Castro-Rodriguez emphasized the importance of recognizing the three forms of HAPE, including reentry HAPE when children return to the mountains from vacation, since these can be life threatening.
My work has been cited in articles by pulmonologists Deborah Liptzin and Dunbar Ivy from Children’s Hospital of Colorado and geneticist Christine Eichstaedt and her team at the University of Heidelberg.
At Ebert Family Clinic we give every patient/family a free pulse oximeter. The ability to measure the oxygen saturation of anyone with cough, congestion, or fatigue can facilitate early treatment with oxygen and prevent visits to the emergency room, hospital and intensive care unit.
I recently received first prize for a poster presentation on HARPE at the fall Colorado Medical Society meeting, and second prize for a poster on Trauma and HAPE.
For more information about HAPE, HARPE and Trauma-related HAPE, see previous blog entries.
References
Ebert-Santos C. High-Altitude Pulmonary Edema in Mountain Community Residents. High Alt Med Biol. 2017 Sep;18(3):278-284. doi: 10.1089/ham.2016.0100. Epub 2017 Aug 28. PMID: 28846035.
Giesenhagen AM, Ivy DD, Brinton JT, Meier MR, Weinman JP, Liptzin DR. High Altitude Pulmonary Edema in Children: A Single Referral Center Evaluation. J Pediatr. 2019 Jul;210:106-111. doi: 10.1016/j.jpeds.2019.02.028. Epub 2019 Apr 17. PMID: 31005280; PMCID: PMC6592742.
Liptzin DR, Abman SH, Giesenhagen A, Ivy DD. An Approach to Children with Pulmonary Edema at High Altitude. High Alt Med Biol. 2018 Mar;19(1):91-98. doi: 10.1089/ham.2017.0096. Epub 2018 Feb 22. PMID: 29470103; PMCID: PMC5905943.
Eichstaedt CA, Mairbäurl H, Song J, Benjamin N, Fischer C, Dehnert C, Schommer K, Berger MM, Bärtsch P, Grünig E, Hinderhofer K. Genetic Predisposition to High-Altitude Pulmonary Edema. High Alt Med Biol. 2020 Mar;21(1):28-36. doi: 10.1089/ham.2019.0083. Epub 2020 Jan 23. PMID: 31976756.
Living in Summit County, Colorado has its perks – residents are within a 20 to 40 minute drive to five world class ski resorts, and some of the most beautiful Rocky Mountain trail systems are accessible right out our back door. With the endless opportunities drawing residents outdoors to partake in physical activity, it comes as no surprise that Summit County is considered one of the healthiest communities in the country. However, there may be more than meets the eye when it comes to explaining this, as it also has something to do with the thin air.
As a Summit County native, you have likely heard the term “hypoxia” or “hypoxemia” mentioned a time or two. So what does this mean? Simply put, these words describe the physiological condition that occurs when there is a deficiency in the amount of oxygen in the blood, resulting in decreased oxygen supply to the body’s tissues. When this occurs in the acute setting, it may result in symptoms such as headache, fatigue, nausea, and vomiting. These are common symptoms experienced by those with altitude illness, also known as acute mountain sickness. While these symptoms can cause extreme discomfort and may put a huge damper on a mountain vacation, they are not usually life threatening. However, in a small number of people, development of more serious conditions such as a high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE) can occur. The treatment for all conditions related to altitude illness is oxygen, whether via return to lower elevations or by a portable oxygen concentrator that allows you to stay where you are. While altitude illness generally affects those who rapidly travel from sea level to our elevation, it has also been known to affect residents returning home to altitude, usually after a period of two or more weeks away. In a very small subset it can occur after a period of only a day or two. This generally occurs in those with a preexisting illness, where altitude exacerbates the condition.
While the acute effects of altitude can clearly have detrimental effects on one’s physical well-being, there is emerging research demonstrating that chronic hypoxia may actually come with several health benefits. Long time Summit County business owner and community pediatrician, Dr. Chris Ebert-Santos of Ebert Family Clinic in Frisco, has spent quite some time studying the effects of chronic high-altitude exposure, and recently attended and presented at the Chronic Hypoxia Symposium in La Paz, Bolivia, the highest capital city in the world.
It is important to first understand the adaptations that occur in our bodies as a result of long-term hypoxia. The ability to maintain oxygen balance is essential to our survival.
So how do those of us living in a place where each breath we take contains about ⅓ fewer oxygen molecules survive?
Simply put, we beef up our ability to transport oxygen throughout our body. To do this, our bodies, specifically the kidneys, lungs and brain increase their production of a hormone called erythropoietin, commonly known as EPO. This hormone signals the body to increase its production of red blood cells in the bone marrow. Red blood cells contain oxygen binding hemoglobin proteins that deliver oxygen to the body’s tissues. Thus, more red blood cells equal more oxygen-carrying capacity. In addition to increasing the ability to carry oxygen, our bodies also adapt on a cellular level by increasing the efficiency of energy-producing biochemical pathways, and by decreasing the use of oxygen consuming processes2. Furthermore, the response to chronic hypoxia stimulates the production of growth factors in the body that work to improve vascularization2, thus, increased ability for oxygenated blood to reach its destination.
So, how can these things offer health benefit?
To start, it appears that adaptation to continuous hypoxia has cardio-protective effects, conferring defense against lethal myocardial injury caused by acute ischemia (lack of blood flow) and the subsequent injury caused by return of blood to the affected area3. The exact mechanism of how this occurs is not well understood, but it seems that heart tissue adapts to be better able to tolerate episodes of ischemia, making it more resistant to damage that could otherwise be done by decreased blood flow that occurs during what is commonly known as a heart attack. This same principle applied to ischemic brain damage when tested in rat subjects. Compared to their normoxic counterparts, rats pre-conditioned with hypoxia sustained less ischemic brain changes when subjected to carotid artery occlusion, suggesting neuroprotective effects of chronic hypoxia exposure4.
Additionally, it appears that altitude-adapted individuals may be better equipped to combat a pathological process known as endothelial dysfunction5. This process is a driving force in the development of atherosclerotic, coronary, and cerebrovascular artery disease. Altitude induces relative vasodilation of the body’s blood vessels compared to lowlanders2. A relaxing molecule known as nitric oxide, or NO, assists with causing this dilation, and in turn the resultant dilated blood vessels produce more of this compound5. The molecule has protective effects on the inner linings of blood vessels and helps to decrease the production of pro-inflammatory cytokines that damage the endothelium5. This damage is what kickstarts the cascade that leads to atherosclerosis in our arteries. Thus, a constant state of hypoxia-induced vasodilation may in fact decrease one’s risk of developing occlusive vascular disease.
The topics mentioned above highlight a few of the proposed mechanisms by which chronic hypoxia may be beneficial to our health. However, do keep in mind that there are potential detrimental effects, including an increased incidence of pulmonary hypertension as well as exacerbation of preexisting conditions such as COPD, structural heart defects and sleep apnea, to name a few6. Research regarding the effects of chronic hypoxia on the human body is ongoing, and given its significance to those of us living at elevations of 9,000 feet and above, it is important to be aware of the impact our physical environment has on our health. Dr. Ebert-Santos is avidly involved in organizations dedicated to better understanding the health impacts of chronic hypoxia, and has several current research projects of her own that may help us to further understand the underlying science.
Kayla Gray is a medical student at Rocky Vista University in Parker, CO. She grew up in Breckenridge, CO, and spent her third year pediatric clinical rotation with Dr. Chris at Ebert Family Clinic. She plans to specialize in emergency medicine, and hopes to one day end up practicing again in a mountain community. She is an avid skier, backpacker, and traveler, and plans to incorporate global medicine into her future practice.
Citations
Theodore, A. (2018). Oxygenation and mechanisms for hypoxemia. In G. Finlay (Ed.), UpToDate. Retrieved May 2, 2019, from https://www-uptodate-com.proxy.rvu.edu/ contents/oxygenation-and-mechanisms-of-hypoxemia?search=hypoxia&source=search_ result&selectedTitle=1~150&usage_type= default&display_rank=1#H467959
Michiels C. (2004). Physiological and pathological responses to hypoxia. The American journal of pathology, 164(6), 1875–1882. doi:10.1016/S0002-9440(10)63747-9. Retrieved May 2, 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1615763/
Kolar, F. (2019). Molecular mechanism underlying the cardioprotective effects conferred by adaptation to chronic continuous and intermittent hypoxia. 7th Chronic Hypoxia Symposium Abstracts. pg 4. Retrieved May 2, 2019. http://zuniv.net/symposium7/Abstracts7CHS.pdf
Das, K., Biradar, M. (2019). Unilateral common carotid artery occlusion and brain histopathology in rats pre-conditioned with sub chronic hypoxia. 7th Chronic Hypoxia Symposium Abstracts. pg 5. Retrieved May 2, 2019. http://zuniv.net/symposium7/Abstracts7CHS.pdf
Gerstein, W. (2019). Endothelial dysfunction at high altitude. 7th Chronic Hypoxia Symposium Abstracts. pg 11. Retrieved May 7, 2019. http://zuniv.net/symposium7/Abstracts7CHS.pdf
Hypoxemia. Cleveland Clinic. Updated March 7, 2018. Retrieved May 9, 2019. https://my.clevelandclinic.org/health/diseases/17727-hypoxemia
Respiratory syncytial virus, RSV, is a common disease that predominantly affects infants and children throughout the world. Symptoms include mild fever, runny nose, coughing, and wheezing (CDC, 2021 and is the leading cause of bronchiolitis and pneumonia in children under the age of 1 in the United States. Because of this high risk of lower respiratory symptoms RSV is also the leading cause of hospitalizations within this age group (Sanofi Pasteur, 2021). Testing for RSV is quick and easy. Children under the age of 5 can be tested for RSV with a nasal swab and rRT-PCR test, similar to COVID-19 home tests (CDC, 2021) available at clinics and emergency rooms. . Unfortunately, preventing the spread of RSV and keeping these hospitalization rates to a minimum is more difficult at higher elevations.
One of our patients during admission after being diagnosed with RSV earlier in the day.
Higher elevations affect the body in many ways. The human body physiologically adapts within seconds of exposure to higher altitudes. Respiratory rate increases in order to compensate for the lower amount of oxygen circulating within the body (Scott, 2018). Within days to weeks, the body begins to acclimate to the higher altitude and this hypoxic state by maintaining this increased ventilation rate and increasing the amount of hemoglobin in the body (Scott, 2018). Due to the combination of effects on ventilation and oxygenation, managing respiratory infections like RSV becomes more difficult.
The correlation between rates of RSV and higher altitudes has been studied more in recent years. It is hypothesized that the physiological changes that the body undergoes at higher altitude predisposes children to respiratory illnesses including RSV (Shi et al., 2015). In one study done in Colorado, the incidence of RSV within the population was higher than those at moderate and lower elevation areas. The rates of hospitalization increased 25% with children under the age of 1 and up to 53% with children between 1 and 4 (Choudhuri et al, 2006). Data shows that as altitude increases, the incidence of RSV increases, with elevations over 2500m considered as a modest predictor of RSV-related hospitalizations. The incidence of morbidity associated with RSV increases with higher elevation as well (Wu et al., 2015). This increased morbidity is attributed to the thick secretions that is caused by the virus. Since infants breathe through their nose until age 3, this collection of mucus causes respiratory issues including pauses in breathing with cyanosis called apnea. With studies showing the increased incidence, hospitalizations, and morbidity of RSV at higher altitudes, diagnoses of RSV should not be downplayed in children living at high altitudes.
Photo of the same patient as above on home oxygen after being discharged from the hospital.
It is important for providers and parents to be aware of the higher risk for more severe disease progression faced by children who reside at higher altitudes. Parents should recognize the symptoms of RSV and practice proper handwashing techniques to prevent the further spread of this disease within the community. Health care providers within these high-altitude areas should consider additional interventions and treatments such as home oxygen or nasal suctioning which may be beneficial to preventing hospitalizations due to RSV. Dr. Chris advises parents with older children in daycare or preschool to consider keeping them home during RSV season (November-April) when they have a new baby in the house. Although it is imperative to properly diagnose and treat RSV to avoid hospitalizations, obtaining a chest x-ray and treating with medications like albuterol or steroids is unnecessary. Ultimately, although RSV is a benign disease to most, in areas of higher elevation, it must be taken seriously order to prevent unfavorable outcomes.
References
Centers for Disease Control and Prevention. (2021, September 24). Symptoms and care of RSV (respiratory syncytial virus). Centers for Disease Control and Prevention. Retrieved April 28, 2022, from https://www.cdc.gov/rsv/about/symptoms.html
Choudhuri, J. A., Ogden, L. G., Ruttenber, A. J., Thomas, D. S., Todd, J. K., & Simoes, E. A. (2006). Effect of altitude on hospitalizations for respiratory syncytial virus infection. Pediatrics, 117(2), 349–356. https://doi.org/10.1542/peds.2004-2795
Scott, B. (2018, June 13). How does altitude affect the body? Murdoch University. Retrieved April 28, 2022, from https://www.murdoch.edu.au/news/articles/opinion-how-does-altitude-affect-the-body#:~:text=Many%20people%20who%20ascend%20to,lethargy%2C%20dizziness%20and%20disturbed%20sleep
Shi, T., Balsells, E., Wastnedge, E., Singleton, R., Rasmussen, Z. A., Zar, H. J., Rath, B. A., Madhi, S. A., Campbell, S., Vaccari, L. C., Bulkow, L. R., Thomas, E. D., Barnett, W., Hoppe, C., Campbell, H., & Nair, H. (2015). Risk factors for respiratory syncytial virus associated with acute lower respiratory infection in children under five years: Systematic review and meta-analysis. Journal of iglobal health, 5(2), 020416. https://doi.org/10.7189/jogh.05.020416
Wu, A., Budge, P. J., Williams, J., Griffin, M. R., Edwards, K. M., Johnson, M., Zhu, Y., Hartinger, S., Verastegui, H., Gil, A. I., Lanata, C. F., & Grijalva, C. G. (2015). Incidence and Risk Factors for Respiratory Syncytial Virus and Human Metapneumovirus Infections among Children in the Remote Highlands of Peru. PloS one, 10(6), e0130233. https://doi.org/10.1371/journal.pone.0130233
Claire Marasigan is a 2nd year PA student currently studying at Midwestern University in Glendale, Arizona. Claire has lived her entire life in Arizona and went to Grand Canyon University for her undergraduate degree in Biology. Prior to PA school, she was a medical scribe trainer at St. Joseph’s Hospital in Phoenix. In her free time, she loves to cook, try new restaurants with friends, and play with her dog, Koji.
One of the phenomena I experienced while caring for pediatric patients in Summit County was the image of a [1] child with an oxygen saturation of 83% who wasn’t in any respiratory distress. This got me thinking: do adaptations in children exposed to chronic hypoxia at altitude prepare them to encounter an episode of acute hypoxia?
It turns out this phenomenon has been studied previously. Children permanently residing at high altitudes exhibit phenotypic variations to help them adapt to their chronically hypoxic environment. According to de Meer, K., et al., for those children living at altitudes greater than 3000m above sea level since gametogenesis, the opportunities for phenotypic plasticity are particularly excellent.
These changes in phenotypic expression have led to both theorized and proven physiologic differences in oxygen uptake, transport, systemic circulation, and consumption, allowing them to overcome the effects of chronic high-altitude hypoxia.
The lower partial pressure of oxygen causes high-altitude hypoxia to those who are visiting from lower altitudes. With less oxygen in the air, increased respiratory effort would be required to maintain the same oxygen levels as those children living at sea level. However, children living at altitude have physiologic increases in ventilation, lung compliance, and pulmonary diffusion, which help negate the need for augmented respiratory effort.
To conserve respiratory rate, increases in lung compliance and tidal volume have been observed in children living at altitude. In one study by Mortola, J. P., et al., lung compliance and tidal volume remained increased even while participants were on 100% supplemental oxygen. This suggests that this is a permanent physiological adaptation in kids living at altitude.2
Additionally, children living at altitude are more efficient at delivering oxygen to their tissues. An increase in pulmonary diffusion capacity facilitates this improved efficiency. Pulmonary diffusion capacity is determined by the surface area available for diffusion. Assuming all other anatomic variables are the same in highlanders and lowlanders[2] , this increased capacity can only be explained by an increase in the number and size of alveoli.1 To study this possibility, researchers compared the lung volumes and chest dimensions of children exposed to chronic hypoxia at altitude since birth to those of children living at sea level and found that lung volumes and chest dimensions of children residing at altitude indeed were greater.
Despite this opportunity for increased oxygen uptake by the lungs of children living at altitude, the partial pressure of oxygen in their blood is still substantially lower. This decrease in arterial blood oxygen concentration that is associated with hypoxia encourages the kidneys to release erythropoietin, which subsequently stimulates the production of erythrocytes contributing to an increased erythrocyte and hemoglobin concentration in children living at altitude. Elevated hemoglobin concentration leads to a relative increase in arterial oxygen saturation, which compensates for the lower availability of oxygen at altitude.1
Despite the witnessed phenomenon of the ability of children living at altitude to adapt to acute hypoxia, it is still debated whether chronic hypoxemia in this population results in decreased oxygen consumption. New research has concluded that previously observed decreases in oxygen metabolism in newborns at altitude are reactions to acute stress and hypoxia and should not be considered an effect of chronic exposure to hypoxia.1 In other words, the ability of children living at altitude to decrease ventilation during an episode of acute hypoxia is due to a decrease in tissue metabolism only during that event of respiratory stress.
Like most things in life, these advantages do not come without consequences. Humans exposed to chronic hypoxia are prone to pulmonary hypertension; in fact, phenotypic, physiological changes in tidal volume and lung diffusion that improve oxygen uptake contribute to pulmonary hypertension. However, unlike children who develop pulmonary hypertension unrelated to altitude, highland children often present with a less severe clinical picture and fewer irreversible complications.1
Children born and residing at altitude offer a window into a world of medical phenomena that are little understood. The more we know about the physiological differences in this population, the better we can serve them as clinicians.
References
de Meer, K., et al. “Physical Adaptation of Children to Life at High Altitude.” European Journal of Pediatrics, vol. 154, no. 4, Apr. 1995, pp. 263–72. Springer Link, https://doi.org/10.1007/BF01957359.
Mortola, J. P., et al. “Compliance of the Respiratory System in Infants Born at High Altitude.” The American Review of Respiratory Disease, vol. 142, no. 1, July 1990, pp. 43–48. PubMed, https://doi.org/10.1164/ajrccm/142.1.43.
Lauren Thompson is a second-year Physician Assistant Student at Drexel University in Philadelphia. She is here all the way from sunny sea level, Florida, where she got her degree in Psychology with a minor in Biology from Florida State University. She is currently completing her clinical rotation, which has taken her all over the country with her feline and canine companions, Duke and Remi. Before PA school, Lauren worked as a Certified Nursing Assistant at a local hospital and a Medical Assistant at a pediatric specialty clinic. Outside of medicine, Lauren enjoys traveling, spending time with her animals, singing karaoke, playing disc golf, and taking in all of what mother nature has to offer, whether it’s hiking, skiing, diving, or enjoying the beach.
Dr. Gutierrez is originally from Mexico City and attended medical school at Universidad La Salle Medical School. He completed his residency at the University of Miami School of Medicine, Jackson Memorial Hospital and has been Board Certified by the American Board of Obstetrics and Gynecology since 1986. He worked in Mexico City with his father who is also an OBGYN before moving to Summit County in 1998. He says that he dealt with pregnancy at altitude even in Mexico City as a young doctor but now has become even more experienced while practicing at St. Anthony Summit Hospital in Summit County, Colorado. In his career he has delivered more than 7,000 babies.
Gutierrez estimates that about 3% of his patients are visitors to Summit County. Most of these patients are not at full term in their pregnancy and present in the ER with signs of premature labor due to dehydration. Usually, these patients are stabilized and sent to Denver for definitive treatment given St. Anthony Summit Hospital only has a Level 1 nursery (basic newborn care).
The most common conditions that he sees occurring in pregnant women at altitude are pregnancy-induced hypertension (PIH), intrauterine growth restriction (IUGR), and small for gestational age (SGA). Because of this, he says that the main difference of observing pregnancy at altitude is more frequent ultrasounds to monitor the growth of the baby. Luckily, most pregnant women at altitude are very fit and healthy because of the active lifestyle that Summit County encourages. However, some women also have a difficult time restricting their activity level enough to maintain proper growth of the baby. The recommended maximum heart rate during pregnancy is 80% of your maximum heart rate, which can be hard to not exceed in an active pregnant female living at altitude.
Nevertheless, the risk of high altitude pulmonary edema (HAPE), high altitude cerebral edema (HACE), and sleep problems are about the same as in pregnant women not living at altitude. In general, pregnant women past 24 weeks have difficulty sleeping no matter where they live. In addition, if you know you are at high risk for developing HAPE or have a history of HAPE you are just as likely to develop HAPE during your pregnancy as you are not pregnant.
Sleeping with oxygen is recommended and has many benefits for all individuals living at altitude, pregnant women included. However, it likely wouldn’t decrease the number of SGA babies because of the activity level of most individuals as mentioned earlier. A woman’s body increases blood volume, red blood cell count, respiratory rate, and vasodilates blood vessels to accommodate for the growing fetus. This in turn allows the body to compensate well and usually maintain normal oxygen saturation levels at altitude. But Dr. Gutierrez feels eventually it will be recommended for everyone to sleep with oxygen, most people just don’t want to.
Especially with dehydration, he has seen very high red blood cell concentrations. However, these individuals usually only need rehydration and do not suffer any complications. He has not seen a drastic increase in the number of blood clots in pregnant females at altitude even though they are likely at higher risk. But if a pregnant female who is dehydrated and recently traveled to altitude presents with shortness of breath, he definitely puts HAPE and pulmonary embolism (PE) higher on his list of possible diagnoses than he would not at sea level.
An important and simple recommendation is increasing their fluid intake. At altitude you have more insensible water loss and are likely more physically active, which in turn can lead to faster dehydration causing premature labor. Luckily this complication is easily managed with adequate fluid intake. In addition, if you know you are at high risk for developing HAPE it is recommended that you do not travel to altitude, especially later in your pregnancy.
The baby lives in a hypoxic environment in the womb anyway so there are no known advantages to living at altitude while being pregnant, other than the active and healthy lifestyle Summit County promotes.
One of the most challenging cases Dr. Gutierrez has treated was severe maternal respiratory distress during early third trimester due to HAPE. The most definitive treatment was to transport her to a lower altitude, however, they had to stabilize the mother enough to be able to transfer her and her baby. In addition, Summit County does not have a high level nursery to take care of a very premature baby even if they were able to deliver the baby safely to take stress off the mother’s body. He said it was a delicate balance trying to determine what was best and safest for both the mother and the baby.
Bailie Holst is a second-year Physician Assistant student at Red Rocks Community College in Arvada, CO. Bailie was born in Longmont, Colorado and spent her life in Northern Colorado until moving to Minneapolis, Minnesota for her undergraduate studies at the University of Minnesota. She also spent her life traveling throughout the country competing in gymnastics competitions and eventually earning a full-ride athletic scholarship for gymnastics to the University of Minnesota. She finished her gymnastics career and graduated with a Bachelor’s degree in Physiology in 2017. Prior to PA school she worked as a medical assistant in a sports medicine and rehabilitation office in Colorado for two years. In her free time, Bailie now enjoys golfing, traveling, spending time with family, and playing with her brand-new puppy.
This is a handout distributed by Dr. Christine Ebert-Santos, MD, MPS, at Ebert Family Clinic, Frisco, Colorado.
Living at high altitude is a challenge for our bodies. The amount of oxygen in the air we breathe is less the higher you go. Since we all need oxygen to live, this can cause problems.
There are three times when oxygen may be needed by children living at altitude:
During the newborn period;
When a child has a respiratory illness, even a mild cold;
During the first 48 hours after returning/arriving from sea level.
When a baby takes their first breath, the higher oxygen level in the air sets off many changes in the heart, lungs and blood vessels around the lungs that convert the child’s respiratory system from transferring oxygen from the placenta to the lungs. Exposure to a low oxygen environment during the first few weeks can interfere with the normal fall in the pressures of the blood vessels in the lungs and closing of the vessels that shunted blood away from the lungs in the womb.
In babies and children, we are not worried about brain damage from lack of oxygen due to the altitude. Don’t panic if the oxygen cannula falls off during the night or the tank runs out. The problems caused by the low oxygen saturations (usually running between 78 – 88%) seen at altitude develop over days, weeks or years, due to changes in the heart and lung. Hypoxia, the term for low oxygen in the blood, causes constriction, or narrowing, of the blood vessels in the lungs. This can lead to back pressure on the lungs and heart, which may cause fluid to leak into the air sacs in the short term or abnormal increases in the heart muscle in the long ter.
Rarely do babies or children with low oxygen levels at altitude show symptoms. The normal oxygen saturation levels at 9000′ are about 92 – 93%, and can be 89 – 90% in healthy people. We start treating with oxygen below 89%, even though symptoms like trouble breathing, fast breathing, poor sleep, or poor color are unusual until the saturation level is in the 70’s.
It is important to understand that oxygen is prescribed by your doctor to treat symptoms of altitude sickness such as headache, vomiting and trouble breathing, and to prevent more severe symptoms from developing. A small percent of persons with mildly low oxygen levels will suddenly, over a few hours, go into full-blown pulmonary edema where their lungs fill with fluid, they have much more trouble breathing, and turn blue. This is a life threatening emergency.
When you arrive home with your child on oxygen, be sure and call the respiratory therapist at the phone number on the tank so they can come to your house and teach you about the equipment. Don’t feel discouraged if your toddler or young child is fighting the oxygen at first. They will usually adjust and accept the cannula in about 30 minutes.
My name is Austin Ethridge, I am a physician assistant student from Red Rocks Community College PA program who has been fortunate enough to have completed my pediatric rotation with Dr. Chris in Frisco, Colorado, this month. Dr. Chris has extensive experience providing care to the pediatric residents of Summit County, having established her practice here in 2000, following 20 years as a pediatrician on Saipan, in the Northern Mariana Islands, southeast of Japan. She has a unique perspective on high altitude health, having transitioned from sea level to the 8000′ and above elevations unique to Summit County. Since moving here, she has been advocating for more in-depth medical research regarding the needs specific to these high-altitude communities. We are here in her office today at the Ebert Family Clinic to discuss neonatal oxygen use in Summit County.
Dr. Chris, based on your experience, why do neonates need oxygen at a higher elevation? Is it because they need to acclimate?
Yes, that’s basically it, and smaller lung size at birth.
Yes, that’s what I read. Basically, the maternal physiology compensates for the higher altitude. When the infant is born, their lung size and physiology need to catch up to the altitude.
Based on your practice, when do you place neonates on oxygen?
Usually at 89% or below, but you see, that’s just it. Many parents ask why their children need to be on oxygen when neither themselves nor their siblings were on oxygen. One of the primary reasons that this has become more of an issue is the less invasive methods of measuring oxygen saturation in the blood. Before the 1990s, the only time to measure oxygen saturation in a newborn was if a concern for illness or pulmonary problems existed, which was completed by obtaining an arterial blood gas, a very invasive procedure. Do you know at what oxygen saturation level we begin to detect cyanosis in neonates?
Around75%, which means before the pulse oximeter used today, we had no idea if the infant’s oxygen saturation was in the 80s! Now that we have the pulse oximeter, we have access to so much more information. And this is why it is essential to determine the normal oxygen levels for these infants at higher elevations.
Does this include cyanosis or blue discoloration of the hands and feet, or is it just central as in the face and chest?
The blue discoloration of legs and arms do not count; this is very common and not concerning, only the discoloration of the trunk and face.
Yes, based on the articles that I have been reading while I have been here, there are not many studies that reflect normal oxygen saturation in neonates at a higher elevation. Most of the articles that I did find determined that newborn oxygen saturation is lower at elevations of around 6000’, with average values within the range of 89-96% SpO2 compared to greater than 97% at sea level. However, there could be a significant difference between 9000’-10000’ feet and the 6000’ in these studies.1-3
That is exactly right, and that is why I want to do a study here in Summit County to determine the average oxygen saturation at these altitudes.
On average, how many newborns do you place on oxygen in Summit County?
About 40% of newborns are placed on oxygen due to low oxygen levels at birth, and I would say that less than 5% will still need oxygen after their two-week visit; however, this rate may be higher in those that live at elevations of 10,000′ or greater. In general, studies have observed that the lowest oxygen levels tend to occur around the 4th day of life and then improve from this point onward. What is the main complication that we are worried about in infants that have low oxygen levels?
Pulmonary hypertension. At birth, when the fetal circulation is shunted back through the lungs, the pulmonary pressure decreases to allow this to happen. If the oxygen levels are too low, the vessels in the lungs may not dilate enough, and this could lead to elevated pulmonary pressures. I read an interesting study that found increased pulmonary pressures in Tibet children as measured by ECHO cardiogram until the age of 14. These pressures were noted to increase with increasing elevation but to decrease with increasing age. Generally, by the age of 14, the pulmonary pressures had normalized; the authors considered this to be a normal physiological response. However, it is worth noting that these children in the study came from generations of individuals that have always lived at these altitudes.4-5
That is correct. That is the difference between adaptation and acclimatization. Many of the children that live up here are acclimatized, meaning that their bodies have adapted on a physiological level, but their genetics remain the same. However, adaptation is observed in many families that have lived at high elevations for generations; in these instances, the changes have occurred at the genetic level.
That makes sense; so the data from some of those studies may not directly apply to the population here.
That is correct. Are we worried about brain damage in this setting of low blood oxygen levels?
No, I do not think so.
We are not! In fact, as an example of this: when I was in Saipan, there was a child that had a cyanotic, congenital heart defect that was unable to be repaired for social reasons. This child always appeared blue, and his oxygen saturation would have been very low. He did just fine in terms of development and progress in academics. There were no signs of developmental delay or any other neurological problems at all.
Are there any resources you recommend for parents whose newborn may need to be on oxygen?
Are there any red flags or signs that the newborns’ oxygen may not be high enough when they are sent home? Is there anything parents should look out for? I know that you mentioned the oxygen level needs to be as low as 75% before there are any signs of concerning central cyanosis.
No, there really are no clinical signs. A company called Owlet produces a sock for the newborn’s foot that monitors oxygen saturation. I am not sure how accurate this is, but if the parents really want to do something to monitor the oxygen level, this could be a way to do so. It is pretty expensive. On an aside, we are currently in communication with this company regarding future opportunities to conduct research using their product with regards to newborn oxygen saturation at higher elevations, so stay tuned for more developments on this topic.
Are there any risks to starting the infant on oxygen?
No, not at the level that these newborns are sent home on. In premature infants, there is a risk associated with oxygen therapy for eye and lung disease. However, these premature infants are placed on very high flow rates and positive pressures. The damage is actually caused by the pressures of the oxygen being too high. This is not the case for the newborns that we place on oxygen.
Are there any risks to infants or children growing up at high altitude?
Yes, there is some evidence of a very slight increased risk of pulmonary hypertension, but this is very rare.
Thank you so much for taking the time to discuss this, Dr. Chris!
References
Ravert P, Detwiler TL, Dickinson JK. Mean oxygen saturation in well neonates at altitudes between 4498 and 8150 feet. Adv Neonatal Care. 2011 Dec;11(6):412-7. doi: 10.1097/ANC.0b013e3182389348. Erratum in: Adv Neonatal Care. 2012 Feb;12(1):27. PMID: 22123474.
Morgan MC, Maina B, Waiyego M, Mutinda C, Aluvaala J, Maina M, English M. Oxygen saturation ranges for healthy newborns within 24 hours at 1800 m. Arch Dis Child Fetal Neonatal Ed. 2017 May;102(3):F266-F268. doi: 10.1136/archdischild-2016-311813. Epub 2017 Feb 2. PMID: 28154110; PMCID: PMC5474098.
Bakr AF & Habib HS, Normal Values of Pulse Oximetry in Natewborns at High Altitude. Journal of Tropical Pediatrics 2005; 51(3) 170-173.
Qi HY, Ma RY, Jiang LX, et al. Anatomical and hemodynamic evaluations of the heart and pulmonary arterial pressure in healthy children residing at high altitude in China. Int J Cardiol Heart Vasc. 2014;7:158-164. Published 2014 Nov 12. doi:10.1016/j.ijcha.2014.10.015
Remien K, Majmundar SH. Physiology, Fetal Circulation. [Updated 2020 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539710/
Thilo EH, Park-Moore B, Berman ER, Carson BS. Oxygen Saturation by Pulse Oximetry in Healthy Infants at an Altitude of 1610 m (5280 ft): What Is Normal? Am J Dis Child. 1991;145(10):1137–1140. doi:10.1001/archpedi.1991.02160100069025
Austin Ethridge is a second-year physician assistant student at the Red Rocks Community College Physician Assistant Program. Originally from the Colorado front range, Austin attended the University of Northern Colorado where he obtained both a bachelors and masters degree in chemistry prior to attending PA school. In his free time, Austin enjoys spending time with his friends and family, reading, and cycling.
Over 800 participants from 25 countries joined the virtual conference this year which included Dr. Chris’ poster presentation on growth at altitude. Over the next several months we will extract the most relevant information to publish in our blog, starting with:
The Rule of 3’s
You can survive 3 minutes without oxygen
3 hours without shelter in a harsh environment
3 days without water
3 weeks without food
Dr. Christine Ebert-Santos presents her research on growth in children at high altitude, “Colorado Kids are Smaller.”
We will be sharing some of the science, experience and wisdom from these meetings addressing how to survive. For example, Dr. Peter Hackett of the Hypoxia Institute reviewed studies on how to acclimatize before travel or competition in a low oxygen environment.
Susanne Spano, an emergency room doctor and long distance backpacker discusses gear, how to build an emergency shelter in the wild, and when it is OK to drink from that refreshing mountain stream.
Michael Caudell presenting on plant toxicity.
Michael Caudill, MD shares what NOT to eat when you are stranded in the wilderness in his lecture on toxic plants.
Presentations included studies of blood pressure in people traveling from sea level to high altitude, drones delivering water to stranded hikers, an astronaut describing life and work at 400,000 m, what is the best hydration for ultra athletes, how ticks can cause meat allergy, and, as always, the many uses for duct tape.
Duct tape for survival.
We will also update you on the treatment of frostbite as well as a discussion about “Climate change and human health.”
Sign up for our regular blog updates so you can be updated on wilderness and mountain medicine!
