A 2009 study from Switzerland found a 12% decrease in risk of death from stroke at 6430 ft. compared to 850 ft. This result was more pronounced in men than women. Since men are more physically active than women in Switzerland, it was thought the exercise at the more hypoxic conditions of higher altitude may benefit them more than for women. The study also noted that being born at a higher altitude had a protective effect on death from cardiovascular disease1.
Strokes occur when blood flow to parts of the brain is cut off causing neurons and other brain cells to die within minutes. Strokes can either be ischemic or hemorrhagic. 80-87% of strokes are ischemic, which means that blood flow to the brain is cut off from a blood clot or other blockage of a blood vessel going to or in the brain. Hemorrhagic strokes are caused by bleeding within the brain (intracerebral space) or in the space surrounding the brain filled with cerebrospinal fluid (subarachnoid space). Risk of stroke is higher in individuals with previous transient ischemic attack (TIA), high blood pressure, previous heart attack, atrial fibrillation, enlarged left atria of the heart, smoking, heavy alcohol use, diabetes, obesity, high cholesterol, and stenosis of the carotid artery2.
Interestingly, on initial exposure to hypoxia at high altitude, blood flow to the brain increases which is split equally between gray and white matter. After 4 to 5 days, blood flow to the brain decreases but is still 13% greater than at sea level. The increased blood flow is needed to maintain adequate delivery of oxygen when the oxygen content of the blood is lower during hypoxia, until other acclimation mechanisms take effect3.
As noted in previous blog posts in response to hypoxia, erythropoietin (EPO) is also released, which increases the production of red blood cells to increase the oxygen-carrying capacity of our blood. Other studies have found that EPO also has a protective effect on neurons. Cerebrovascular endothelial cells have been found to have receptors for EPO and are thus able respond to EPO. Other studies have found that EPO is also involved in brain development of a fetus in utero. Animal studies suggest EPO not only protects neurons from cell death but may enable their regeneration as well. If this translates into humans, it is an important effect for those at risk for stroke4.
In a small clinical trial, patients with middle cerebral artery stroke received IV EPO daily for 3 days after their stroke. These patients had better neurological outcomes with increased physical functioning and independence as measured by Barthel index test results. Following the EPO doses, the size of the cerebral infarct, the damaged area of the brain from blood being cut off during the stroke, was reduced as well4.
Based on this research, Ismailov hypothesized that in the United States, geographic variation in levels of EPO from altitude differences may account for the differences in risk of death from stroke. He termed it the “stroke belt” in the Southeast, with higher rates of death from stroke compared to the Mountain states.
The states in the “stroke belt” are Louisiana (LA), Mississippi (MI), South Carolina (SC), Alabama (AL), Georgia (GA), Arkansas (AK), Indiana (IN), North Carolina (NC), Kentucky (KY), Tennessee (TN), and Virginia (VA), and all are at lower altitude. The mountain states have higher altitude and are North Dakota (ND), Kansas (KS), Nebraska (NE), Arizona (AZ), New Mexico (NM), Wyoming (WY), and Colorado (CO).
Louisiana and Mississippi’s average altitudes are 100 and 300 ft. compared to Colorado and Wyoming with average altitudes of 6800 and 6700 ft4. Since there is increased EPO released in individuals living at higher altitudes, perhaps there is more of a neuroprotective effect at higher altitudes, contributing to the observed lower risk of death from stroke seen in the Swiss study.
Symptoms of Stroke5
Other signs are sudden
Numbness of face, arm, or leg and particularly numbness on one side of body
Difficulty seeing out of one or both eyes
Feeling of dizziness, loss of balance, or coordination
Stephanie Schick is a Physician Assistant student at Rocky Vista University in Parker, CO. She is born and raised in Fort Collins, CO. She started off her clinical year working in pediatrics with Dr. Chris at Ebert Family Clinic. The remainder of her clinical year will be spent closer to home in northern Colorado. In her free time she enjoys spending time with her husband, friends, and family in the beautiful Colorado sunshine.
We’ve learned a lot in the high country this season! For example, it isn’t too late or too warm for a snowstorm. We’ve conducted several interviews with professional, high-altitude athletes, athletic and tourism organizations in Summit County, physicians, podcasters, interns, and a local brewer. They’ve shed so much light on fitness, health, child growth & development, and acclimation at elevation, it warrants a re-cap:
8,000 ft. seems to be the pivotal elevation at which the body starts to experience a significant deficit in the oxygen and water it needs to function, affecting everything from sleep to metabolism.
A plant-based lifestyle has benefitted athletes under extreme training and competitive conditions at altitude.
Training at altitude significantly reduces your ability to reach cardiovascular and strength goals, even while preparing your respiratory and circulatory systems for the severe decrease in oxygen. “Live High, Train Low” is an effective strategy more and more athletes are advocating for.
Preparation for backcountry excursions is as much mental as physical.
Foods high in nitrates (like red beets, red bell peppers and arugula) can facilitate acclimation and recovery.
Oily foods may inhibit your body’s ability to cope with a significant increase in altitude.
We metabolize and experience the effects of alcohol differently at altitude.
Current research suggests some people suffering from Parkinsons disease may experience some relieve from symptoms at higher elevation.
Increased muscle mass requires increased oxygen. Being an athlete does not necessarily mean you will have an easier time acclimating.
As always, the best way to facilitate acclimation and deal with symptoms of altitude sickness is to drink plenty of water, allow yourself ample rest, and monitor your blood oxygen saturation levels with a pulse oximeter.
Be sure to subscribe to keep up with what this summer has in store for your elevated experiences at altitude! And if you have any questions or are eager to read more about a particular topic, let us know in a comment!
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.
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
Yuki Ikeda has been a professional cyclist for the past 10 years. He’s won titles in both Japan and the US. Interestingly enough, however, he come to Colorado to study at Metro State in Denver in order to play pro basketball. He is now known as an Ultra Mountain Athlete, not only biking, but running races up to 100 miles at altitudes over 10,000 ft. Over some decaf coffee on a warm Sunday afternoon at Gonzo’s in Frisco, he tells me he tried out every semester for the college team and failed. He had never really explored outdoor recreation growing up in Japan, because he had been so focused on a career in basketball.
He started taking some classes on outdoor sports while he was in Colorado, at Metro and then at Red Rocks Community College: rock climbing, cycling, backpacking, kayaking … He ended up staying in Colorado after graduating from Metro. “At that time, I was so into mountain biking,” he says. “I decided to pursue my career in mountain biking.”
He started racing in 2002. It took him five years to accumulate sponsors and become a full-on pro. “After every season, I sent my resume — racing results and what I do — to so many teams [to see if] they [would] accept me or not.”
But he started to get burned out. While he was still improving his stats, he was noticing that he couldn’t maintain the lead against some up-and-coming younger racers. “I was mentally very tired the last couple of years. I was kind of frustrated. Last year, after the season, I was so bummed out, I didn’t want to ride my bike, and I didn’t feel like starting training for the next year, so I stayed away from biking. I didn’t even touch my bike for a month.”
“But I still wanted to do some exercise. I just followed my wife, running, then I kind of joined the local trail running community. They showed me where to go and where to run, and I just loved it. I was so into mountain biking only, I thought doing other sports might cause injuries and effect my career. But it was the opposite.”
His new love for running turned his career around. “Physically, I don’t know [if it has improved my biking] yet, but mentally it helped. Now, my training is still 60 – 70% cycling, but not all the time. When I get on the bike, my brain is still fresh. Before, I rode my bike every day, pushing hard every day. It burned me out.”
Last month, he ran his first ultra running race, 50K. “Last October, I got sore from just running only 5K. Now I an run 50K, so that’s awesome.” He won.
Ultra Training at Altitude
I ask him how he trains for these races. Every summer, he comes to Colorado, staying in Frisco or Breckenridge to train in preparation for a series of races at altitude. It usually takes him 10 days to almost 3 weeks before he can do the same workouts he does at sea level in Tokyo.
Threshold power key. Threshold power is the maximum power you can sustain for about 60 minutes. He has a power meter on his bike that measures the power he exerts in watts. Recently, he has also been wearing a similar device on his shoe for when he runs.
“In Tokyo, my number is 310 watts, but here, it’s almost 270 to 280. I just did a threshold test last week. So that’s almost 10 to 12% lower. But still, if it’s within 10 to 15%, that’s very good for this altitude. But I usually take the test after a week or 10 days after I get here. I cannot push myself hard enough [before that]. Even [if] you’ve adjusted to this altitude, your power number is still lower than at sea level. I feel like I’m weak, but you have to accept it. That’s just how it is.”
His next race is part of the Leadman series, consisting of 5 mountain biking and trail running races in Leadville, Colorado. This next one is 42 km. Originally, the trail takes the runners over Mosquito Pass, which is at over 13,000 ft. But this year, there is still so much snow that the trail has been re-routed, so the runners aren’t sure what to expect. But the race starts at over 10,000 ft.
To train for this, he’s been running and biking six days a week. Every morning, he measures his blood oxygen saturation using a pulse oximeter. The first morning he arrived in Frisco, it was at 92. After a couple weeks of acclimation and training, it’s pretty reliably at 96 every morning.
Yuki claims the most difficult part about running these long races is pacing. His coach encouraged him to run “negative splits”, increasing his speed toward the end of the race. “At my first 50 km race, even though I won it, I could have paced myself better. I just went too hard at the beginning [to] take the lead and paid for it later in the race. I was so trashed after the race, I couldn’t even stand and walk.”
“My coach is saying to be careful about [hitting the wall] at altitude. It’s so hard to recover. It takes almost five times longer than at sea level. I need to pace myself, especially for running 100 miles,” Yuki says, referencing the Leadville Trail Run in August he is also preparing for: 100 miles at altitude. “I’m so excited, but at the same time, I’m so nervous. Even finishing is questionable at this point.”
His secret to acclimating comfortably and quickly is actually movement. He says he feels the affects of the elevation more when he’s sedentary. In order to get more oxygen to his body, he has to get his circulation going. “The first week, I feel better when I exercise than when I just sit [around]. “
Also, beets. And red bell pepper. And arugula.
He eats a limited portion of these every day he’s at altitude. These vegetables provide a lot of nitrates, which your body processes into nitric oxide, facilitating blood circulation. At altitudes over 8000 ft., where you have access to about a third of the oxygen available in the air at sea level, the key to supplementing the oxygen your body requires is increased blood flow. After a certain amount of time, your body starts creating more oxygen-carrying red blood cells to counter the deficit, so getting the blood moving is literally vital.
According to high-altitude growth and development expert Dr. Christine Ebert-Santos, nitric oxide is often the way newborn babies with complications at altitude are treated. Hypoxia (the state of receiving less oxygen than is normal at sea level) causes pulmonary vessels (in the lungs) to constrict. Putting these infants on nitric oxide gas dilates the pulmonary arteries and improves some types of respiratory distress.
There are powders marketed to aid the food version of this nutrition, including BeetElite, Yuki’s product of choice, which he’ll add to his sports drinks in addition to consuming about an ounce of roasted beets. But portion control is also important, as too much nitrate can also have a negative effect on the body.
Yuki is learning that he has to deal with an interesting phenomenon when it comes to his ultra running races: it’s tough on his guts. When it comes to his diet, he doesn’t typically change anything for recovery after a long event. “But I think my guts are more tired, because your body is bouncing so much from running.”
When running these incredible distances, he fuels his body with an energy gel every 20 to 30 minutes while running. “It usually has about 100 to 120 calories. It’s a dense energy. Then you take them for five hours, continuously, so it also tires out your guts. During the race. You have to maintain your blood sugar and keep your muscles moving. My muscles are tired, but also, my intestine and stomach are tired.”
“Even water is hard on my stomach [after running a race]. I’m kinda worried about running 50 and 100 miles. I’m not only worried about my legs, but even my stomach. I’m not used to [consuming] energy for 20 hours, eating and running at the same time.”
In Japan, hot springs and bathing are also a huge, sacred part of the recovery and health ritual. He takes a hot bath almost every day, “especially in winter,” he says. “It helps me to sleep at night.”
The first week he spends at altitude in Colorado, he finds it harder to fall asleep. “I used to take one or two melatonin capsules every night, but it’s hard to tell if it helped. I just go to bed early, like 8 or 9, even if I cannot fall asleep. I just take the time to lay down and recover. [I try to sleep] at least 7 to 8 hours a night, but sometimes it’s hard. If I can’t get that amount of sleep, I usually take a nap after training.”
This may sound obvious, but sleep is when your body does most of its recovery, both mentally and physically. Sleep experts and studies have proven that the body and brain visibly deteriorate after so much sleep deprivation. And at altitude, with less oxygen available to supply a body in constant motion, sleep may be more important than ever.
Yuki isn’t the first high-altitude athlete I’ve spoken to who advocates for a plant-based lifestyle. In a recent blog, skier and duathlete Cierra Sullivan also tells us about how a plant-based diet seems to make a big difference.
“When I used to like and eat animal products a lot, my recovery time was slower than now. It was hard to digest animal fats. I believed that they had a lot of good protein, but it was so hard on your body and digestive system,” Yuki says. “It took time to change my diet, but I now feel more comfortable with my plant-based diet, physically and mentally.”
Live High Train Low
Another recurring theme among high-altitude athletes.
“One of my sponsors has an altitude tent. They leased it to me before the competition, so I used it about a month. I slept in the tent, set at about 3000 m, then I train at sea level. I think it helped a bit, but it might be too short to tell. It tired me [out], though. I think I needed to do it longer before the competition, like, two or three months. I couldn’t train well, because I felt tired all the time. But I think for altitude training, I think this elevation is almost too high. Because you cannot push to your maximum potential. For example, for cycling, I can push up to 1000 – 1200 watts at sea level, but I cannot hit that number here, so I cannot train in that range here. I can lose that high power if I stay longer here. But it depends on your [goal]. My [goal] is winning the Leadman series, that’s why I’ve come here to train.”
This is partly why Yuki will lift weights once a week when training at altitude, “to maintain my high power.” With such limited access to oxygen, athletes up here can’t reach the same “punching power” that they can at lower elevations, so lifting may help maintain that power. “Very short, maybe 45 minutes, once a week, just to maintain. Weightlifting is still supplemental for your specific sport, so I don’t want it to affect my training on my bike or running. For race week, I don’t lift weights, because lifting weights takes time to recover.”
Keeping It Fun
“My trick to keep going — the best way to improve yourself,” Yuki adds, in a final reflection, “is to keep it fun. If you’re not having fun, I think that’s not good. Last year, I almost lost my motivation as an athlete. I almost thought about quitting racing, but I still love the sport. Trail running helped me mentally and physically, and my motivation came back, even for cycling. Having fun is the key to keep going.”
Thank you, Yuki. I completely agree. And best of luck with that 100-mile trail run at 13,000 ft.! Keep track of Yuki’s race schedule, social media and stats at http://yukiikeda.net/
Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.
Ski America is a company that has organized accommodations and itinerary for international athletes and vacationers at ski areas around Colorado since 1988. The Omori family, Ski America’s founders, lead their clients on tours of Colorado’s most renowned mountains, including Aspen (8,040 ft.), Vail (8,120 ft.), Beaver Creek (8,100 ft.), Copper (9,712 ft.), Keystone (9,280 ft.), Breckenridge (9,600 ft.) and Arapahoe Basin (10,780 ft.).
Jimi Omori started Ski America as a tour operator for Japanese skiers and snowboarders. Ryoko joined in 2005, and now Ski America’s service is more than tour operating, assisting from first-time skiers of age 3 to professional racers. With over 30 years of experience guiding amateur skiers and international athletes alike, the Omori’s have made some fascinating observations of how people adjust to the high altitude environment of the Rocky Mountains.
The other day, Ryoko shared some of their valuable insight and experience with me over a cup of tea:
How long do your clients typically stay at altitude?
So we have two different kinds of customers. In November until early December, we have a lot of Japanese racers from Japan. They are high school kids, college students. They stay two to four weeks here, in Frisco or Copper Mountain. Then, from December to April, we have clients from Japan who stay in Vail or Aspen. Most of them are senior skiers, over 60 years old. They stay about a week in Vail or Aspen. Six nights is very average.
How often do you get repeat customers?
Quite a lot. Not all of them come back every year, but more than once. I would say, 70%.
Do you see new customers every year?
How do you advertise in Japan?
Word of mouth.
How do you prepare your customers for the altitude?
When I set up the reservation for them, I send them the lodging confirmation and shuttle confirmation, how to get to the Colorado Mountain Express counter at Denver International Airport. With that information, I also send how to get ready for this altitude by e-mail to every customer: Don’t stay up all night before coming over here, don’t overwork before coming here, most importantly, don’t catch a cold before coming over here. That’s the most important thing. And keep yourself hydrated on the flight and on the shuttle. You can always stop at a restroom on the way from the airport to get here. Do not drink a lot [of alcohol] on the flight, and especially on the first night staying here. I encourage them to drink two liters of water a day.
They are so excited to be here, so they tend to forget about the altitude, because there are all the trees, it’s not above the tree line here. In Japan, [this elevation] is way over the tree line. So I always remind them, “You are going to be almost [at the elevation of] Mt. Fuji. So, move slow the first and second day of staying here.”
What about conditioning, physical exercise to prepare? Are they athletic?
They’re pretty much athletic. They’re avid skiers. They ski in Japan regularly. So I do not give them any athletic advice in Japan.
Do they come straight from Denver up to elevation, or do they stay in Denver a certain amount of time?
No. The flight arrives at 12:30 or 1 pm, so it’s very convenient for them to get on the shuttle in the afternoon, and they will be here before 5 or 6.
Do they ski the next day?
Most of them, yes.
What about oxygen or medication? Do you ever tell them to bring ibuprofen or anti-nausea medication?
No. But if anything happens here, I recommend taking [something] for a headache, like Advil.
What is the earliest sign that something might be wrong or that they need medical attention?
Headache. Or sometimes nausea. We had 150 racers last November, and out of 150, I took 5 kids to the clinic for altitude sickness symptoms.
Is it at the beginning of their stay?
Very beginning. [Typically] the second day of skiing. They are okay on the first day. They do not notice anything on the first morning, so they feel, “It’s okay, let’s go skiing!” and spend the day on the mountain, and they have jet-lag, and they can’t sleep well on the second night. And on the second morning most of them notice the symptoms. Those are the Copper clients. And I have 350 guests from Japan staying in Vail and Aspen. Last year, I didn’t see anyone get sick. So it’s only in Summit County, because it’s much higher.
Do you think there are any other correlating factors, like their age or where they’re from?
Age. The racers are from middle school to college, so they’re young. Their hormone level is not stable. And they are staying with their other teammates, apart from their parents, so it could have some emotional factors affecting them, too. But at the same time, the racers have a lot of muscle that needs a lot of oxygen. The higher metabolism that younger kids have [make them] more prone to high altitude sickness. The clients who stay in Vail or Aspen, they are much older, like, 40s, 50s, 60s. And they’re not as athletic as the racers. They do not do any training. So their basic metabolism is low, so I believe they do not need as much oxygen.
Does anyone come from a high elevation in Japan, or is it mostly sea level?
Mostly sea level. Only some of them are from Nozawa, it’s about 1000 m (3,280 ft.), so it’s much lower than Denver.
Is there a difference between the guests that come from Nozawa and the guests that come from sea level?
No. Whenever I see the doctor in the ER, or the Copper clinic, they always say it’s dehydration. No matter how much we tell them to keep hydrated, it’s not enough.
So what does the ER or clinic often give them besides fluids?
Oxygen. And they say it’s okay to take over-the-counter headache medication.
How long is their visit to the hospital? Is it just a couple hours, or do they stay overnight?
Just a couple of hours, or less than that.
Do they ski the next day?
Most of the time, the doctors say not to ski the next day. We carry a pulse oximeter in our office. We have 20 of them. We do not do this for the Vail clients, because they don’t get altitude sickness. So we only do this for the guests staying in Summit County. When we [check them in], we distribute pulse oximeters, one per room. We encourage them to measure [their oxygen level] every morning. Then, after the doctor’s visit, the doctors say it’s okay if your oxygen level is over 90%, 20 minutes after getting off oxygen.
What’s the lowest you’ve seen the oxygen level on any of your skiers?
38. [He was] 15. He was at the ER. He was transferred to Denver by ambulance. He was there about three nights, and he went back to Japan.
Was that the only time somebody had to go back to sea level?
Yes. But it sounds like he had a heart issue, which we didn’t know [about].
Have you witnessed any other factors that help them acclimate more effectively?
I encourage them to eat carbohydrates instead of getting a lot of oily foods. If you have a lot of french fries, it’s very oily, it will take more time and blood to get to the stomach. So the blood flow doesn’t go through the brain [well].
What about caffeine or other holistic remedies?
No. We have some repeating guests who had … symptoms in past years, and we encourage them to visit a doctor in Japan [who] can prescribe … Diamox. One of the ski coaches [from Japan] … has to be here with his team. He has no choice. And he’s [had] a lot of altitude sickness in the past. So we told him, “You should see a doctor and get Diamox prescribed, and start taking it before leaving Japan,” and it’s been working great.
Is there a routine that your clients do to prevent feeling this sickness?
Just check blood oxygen level every morning.
Of the clients that come here regularly, do they acclimate quicker each time?
They learn. We always see lower numbers of altitude sickness patients, because they learn what they need to do, like drinking a lot of water and checking their blood oxygen level. And only the numbers can tell. Even if they feel good, if the numbers are bad, if they go skiing, they will have a problem. Especially for the young kids. They [don’t] trust what you say. As the years go by, the coaches will learn, and the kids will learn what they can and what they cannot do.
Is there anything different about the philosophy of treatment in Japan vs. the US?
You know what, we do not have altitude sickness in Japan. Only if you climb up Mt. Fuji, in one day, it could happen, but not everyone does that. The highest elevation of one ski area in Japan is about 2000 m (6,561 ft.). No one has experienced high altitude sickness in Japan.
When I climbed Mt. Fuji, I saw a lot of people with cans of oxygen that you can spray. Do you ever use or recommend that?
No. I don’t think it works. If you breathe it for five minutes, it will work for five minutes. So I guess it’s very effective if a ski racer uses it right before the start [of a race]. I believe some of our Vail clients [have seen] the bottle and have purchased it, but I’ve never heard anything about it, good or bad.
In closing, I asked Ryoko if she’d noticed a change in her own physiology since living at high altitude, to which she replied that she is always impressed by her increased stamina and speed when she steps on a treadmill back at sea level. I asked her if she ever experiences symptoms upon coming back to a high altitude from sea level. “No,” she says, laughing. She doesn’t typically engage in any strenuous activity the first day or two after travelling, “because I’m lazy,” she says.
Roberto Santos is from the remote island of Saipan, in the Commonwealth of the Northern Mariana Islands. He has since lived in Japan and the Hawaiian Islands, and has made Colorado his current home, where he is a web developer, musician, avid outdoorsman and prolific reader. When he is not developing applications and graphics, you can find him performing with the Denver Philharmonic Orchestra, snowboarding Vail or Keystone, soaking in hot springs, or reading non-fiction at a brewery.
A child in my clinic had a small appendage in front of her ear, called a preauricular tag. I told the mother that I had just returned from a conference where I learned these are more common at high altitude. She replied, “But his father has one also.”
“Yes,” I explained, “There is an interaction between the genes and low oxygen.”
Birth defects can be increased or decreased by the chronic hypoxia at high altitude. Geneticist Igor Salvatierra from the Hospital Materno-infantil discussed the interaction between oxygen levels and chromosomes at the Chronic Hypoxia conference in La Paz, Bolivia. He focused on a deformity we also see more commonly in Summit County, Colorado at 2800 meters: outer ear deformities – microtia. Birth defects can be structural, like the outer ear, or functional, such as deafness, and occur in 1 out of 33 infants worldwide. Only 50% of abnormalities can be linked to a specific cause. Club foot is an example of a birth defect that is less common at higher elevations. In contrast, microtia is three times more common, with preauricular tags twice as common as at sea level. This is due to the interaction between genes and the environment.
Research has identified an enzyme called Jarid1B that is affected by hypoxia, including sleep apnea, copy number variation (CNV) and epigenetic factors such as stress and diet. These act on chromosome 1q32.1 to change the coding of proteins involved in the development of ear cartilage very early in fetal development.
At lower altitudes, the hypoxic environment can be caused by sleep apnea. In early pregnancy this could be one of many factors that, if added to the genetic predispostion, could cause a deformity in the fetus. Luckily the fetus is fully formed before the sleep difficulties in late pregnancy.
Should pregnant mothers or women who are hoping to conceive sleep on oxygen?
From what I learned in La Paz, not necessarily. There are factors in our low-oxygen environment that decrease our risk of other diseases.
Dr. Christine Ebert-Santos recently sat down with Colorado Children’s Hospital’s Pediatric Emergency Medicine physician, Dr. Alison Brent, to share her experience and expertise in high altitude medicine.
After having practiced for decades in the Commonwealth of the Northern Mariana Islands, Dr. Chris opened her own practice in the high mountain community of Frisco, Colorado, where she has spent 20 years servicing natives, transplants and visitors alike. The mountain communities in Colorado are found at elevations higher than any others in North America, and are among the highest in the world. It has become her legacy to contribute to the research and improvement of medical practice in high altitude environments across the globe.
The full podcast episode from Charting Pediatrics can be found on Spotify, Google Play, and the Apple Podcast app.
Dr. Brent: “I know that sometimes in these South American countries, the high altitude illness impact for children can be even greater than what we see in the US.
Dr. Chris: Well, that’s where you get into ‘acclimatization vs. adaptation’. And what doctors in the United States need to know is that, just because a person lives at high altitude in the United States, we may be acclimatized, but we are not adapted, like the natives of La Paz and Nepal. So therefore we don’t have hundreds of generations changing their genetic adaptation to high altitude. We may have 20 years or 40 years. So the risks are still there.
Dr. Brent: Wow, it’s an amazing process. I know that when I moved to Colorado from flat-lander country, I found that there were just huge textbooks on high altitude illness. And it’s fascinating that you’ve taken this over as a very important part of your career.
Dr. Chris: Yes, well we have 5 million tourists every year coming just to Breckenridge, so it’s probably 10 million to Summit County. Plus, we take care of all the children in the surrounding communities, Park county and Lake county, which are higher: over 10,000 ft. So it’s very important to be aware of anything that can come up in both our visitors and our residents.
Dr. Brent: So this very important topic doesn’t just apply to practitioners who might live in Colorado or other mountainous areas. It really applies to practitioners all over the world who have patients who may travel to these areas. And with that in mind, when you have a practitioner and a family who live near sea level and they’re planning a trip to the mountains, how do they start to advise that family on how to get ready for a trip to a high altitude area?
Dr. Chris: I occasionally do get calls from physicians and families who are planning to bring their children, especially if they have a very young infant or a child with special needs. And so, things that I like to tell them are, Number One: If you could travel by wagon, train or mule, you would be best adapted to high altitude, because arriving to high altitude gradually helps your body adapt.
Second best to that is to stop over an intermediate altitude area. Fly into Denver and spend the night there before you come up to the very high altitude areas, especially Summit County. You start to get altitude symptoms around 8,200 ft. or 2500 m, which is the altitude of Vail. If you’re at a lower resort, most of the other resorts in the United States are below 8000 ft., and the risks of altitude illness are not as great. But the rewards of coming to the Colorado Rockies are also greater, because we have seven world-class ski resorts within an hour of where my office is, so it’s definitely worth it. Just arrive, take your time getting up there, relax, try not to do anything too strenuous the first day.
Consider taking Diamox or acetazolamide; the pediatric dose is 5 mg per kg per day, maximum of 125 BID. This has an effect of increasing your ventilatory drive, and definitely decreases the risk of acute mountain sickness when people come to visit the mountains. It’s best to start the day before, but even starting when you get up there works. And if you go to the Hypocrites app, you will find that it is listed for altitude sickness prevention.
Thirty to fifty percent of people visiting the mountains, especially when you fly right in and drive straight up, will experience some symptoms of acute mountain sickness, whether it’s a little nausea or vomiting or headache. So be prepared with some ibuprofen with dose appropriate to the age of the child, and Zofran would be a good thing to have in your pocket, too. It could save you a trip to the ER or doctor’s office. Because we’re just talking about the first 24 to 48 hours. If you could keep everybody in your travel team comfortable, you will have a great vacation.
Now, once you get there, or if you can before you arrive, we tell everybody, “You should have a pulse oximeter.” It’s just a little finger clip. At our office, they cost $17. Walgreens might sell them for $30 or $36. Knowing that oxygen level tells us everything.
You can call me anytime. I give my cell phone to all my patients, because … we need to know when someone’s oxygen is outside the normal range. If it’s below 90, we may want to see that child or even adult, because we do have family nurse practitioners, more urgently. And that is the key piece of information for knowing how sick someone is, and whether they need to be seen within a few hours or can wait until the next day.
Dr. Brent: Do you just prescribe oxygen if their oxygen saturation is low, or do you like to see them as well?
Dr. Chris: We can send oxygen anytime, day or night. We have three oxygen companies, and I can call them up and give them your number and location. I do, of course, want to see anybody that I’m prescribing oxygen for, but I may not have to see them in the middle of the night. Especially if everything sounds classic. My own patients that I’ve already identified as having a risk for Re-entry High Altitude Pulmonary Edema (R-HAPE), we can just set that up, even ahead of time.
Dr. Brent: You know, one of the things that I’ve noticed popping up in the mountains are oxygen bars, where, essentially, people can use an oxygen concentrator at a bar to relieve some of their symptoms. Should we think about preventative maintenance and getting people coming up here set up with oxygen before they come, or do you like to measure the oxygen saturation before you give oxygen? Because people say they just feel better having a little oxygen in the mountains.
Dr. Chris: Definitely the non-prescribed sources of oxygen, such as the canisters that you can buy in every store and the oxygen bars can help you with your headache and nausea. Use that for 10 or 20 minutes, feel better, that may be all you need.
Dr. Brent: And then what about the kids who you might see who have an oxygen saturation less than 90%, you see them in your office. How does the treatment plan roll out from there?
Dr. Chris: So the biggest concern we have is High Altitude Pulmonaryt Edema (HAPE). Now, don’t be scared, this is less than one percent of visitors, and probably between one and two percent of residents. The risk of developing HAPE is increased in anybody who has an inflammatory process going on, such as a cold or influenza. It definitely can occur in the first 24 to 48 hours in visitors, or even up to five days in our resident children who have a cold or some other underlying illness. So we do want them to have a pulse oximeter. This can develop fulminantly so that they’re doing fine for the first 24 hours or the first 4 days of their cold, and then all of a sudden, they kind of gas out, and they’re just lying on the couch and not eating well. Or it can develop very slowly.
So what we like to do if we know their oxygen is low, and whenever we see them in our office the first thing we do after the history and physical is to try an albuterol treatment and inhalation in case there’s some underlying broncho-constriction or asthma component. That would basically be most helpful in families with a history of asthma, or families that tell me they’ve used albuterol … before with that child or personally. It doesn’t usually change their need for oxygen. But it might help their cough.
However, once we do start somebody on oxygen in the office and call the oxygen company to set up a home concentrator, we see them back the next day and parents will tell me their cough was much better using oxygen. So oxygen is the main treatment. We are always thinking, “Could this person have pneumonia? Could this person have asthma?” Because of my experience at sea-level and taking care of very sick kids, if you have somebody with an oxygen level of 79 or 85, and they had asthma, you would certainly know that. You would hear some wheezing, there would be retractions, rails. They’d be in distress. If they had pneumonia, they’re sick, they’re not eating, they have a fever, you hear vocal changes in their respiratory findings. Most of these kids that we see, both the residents and the tourists with HAPE, we often won’t hear anything in their lungs, because children, how often can you get them to take a deep breath. And we often won’t see anything on the x-ray, so I don’t typically do an x-ray until the following day. If they’re not better and the parents are still concerned, we will do an x-ray. Often the x-ray won’t show anything. And this is where I’m hitting my head against the wall, and why it took me nine years to get my first publication. Because high altitude experts and all the pulmonologists are just freaking out that what I’m calling HAPE, or HARP, High Altitude Resident Pulmonary Edema, often does not show changes in the x-ray, and that I don’t do x-rays on all these hypoxic kids I see, because I know they’ll do fine if they just get some oxygen.
Dr. Brent: I love that approach of less is more, so we totally support that at Children’s Colorado. If you think a child has more than acute mountain illness and they actually have some degree of HAPE or HARP, how do you treat them differently?
Dr. Chris: Basically, oxygen. Now when a family arrives for their vacaction, and they’ve got, you know, ten family members in a condo, and one of the kids is sick, you know, we want to have a low threshold treatment. Influenza: we’re gonna put everyone on Tamiflu so that it doesn’t spread. You know, possible strep throat or is there any possible role for anti-biotics, we’ll have a low threshold.
And then we really sell them on the oxygen. You guys don’t have to leave. Your kid will adjust to the oxygen. We have things on our blog on how to keep your two-year-old from taking off their oxygen canula. That can save your whole vacation if you just understand that oxygen is the treatment, that you don’t have to go downhill.
Every once in a while we do have someone sick enough that we will send them down to Denver, directly to the hospital. But a lot of parents will ask me, “Well, what if I just take my kid instead of putting on oxygen, we’ll go down and check into a hotel in Denver?”
I’m not too happy with that, because I [say] you have to be under medical supervision, you have to know that your child’s oxygen is good once you get to Denver. As long as you’re here in the mountains, I’m your physician, you can call me anytime day or night, we can change our plan if it’s not working. If you’re in the condo and you don’t think your child is doing well, we can put your child in the hospital or send them down to a lower altitude if things are not going well.
Dr. Brent: So Chris, a lot of the literature does say that … one of the treatment plans would be to go to lower altitude, but you’re saying they can just stay in the mountains with oxygen and salvage their vacation.
Dr. Chris: Absolutely. We do it many times, every week at our clinic and in the emergency room. They do it every day, I’m sure.
Dr. Brent: Absolutely. Well, often times, when they do get down to see me in the ED, it’s a pretty easy diagnosis of, usually, some variant of acute mountain illness, and often times they’re better when they get to Denver from when they were up in the mountains. They may no longer have an oxygen need. And those kids who are then going to go back up, I hate to change anything that you or another pediatrician may have done, so we usually just keep them on their oxygen, and if the family wants to try going back to salvage their ski vacation, we let them do that.
Dr. Chris: As long as they have a home pulse oximeter, that little finger clip, they will know when they need to call someone.
Dr. Brent: That is wonderful. You mentioned a few of the co-morbidities that you worry about in children who may have an underlying influenza or some reactive airway disease. Are there other conditions, like kids with Down Syndrome or any other special groups that you worry about?
Dr. Chris: Definitely Down Syndrome children are a concern. Of course, I have many Down Syndrome children in my practice, and they do fine. But Down Syndrome children do have airway problems because of their hypotonia. So they’re more likely to need CPAP or have poor oxygenation during sleep. They’re more likely to have pulmonary hypertension or cardiac defects in general. And they also have increased pulmonary vascular reactivity. So … if you’re going to take a vacation and bring your child to altitude, make sure you have a pulse oximeter and that you are watching them very carefully for signs of decreased energy, poor feeding, color, anything that … is concerning that you as a parent are wondering, “This is not normal for them.”
All children, and even adults, when they come to altitude, they do have a decreased appetite. So that can last for months. Also sleep issues. There’s central apnea that is universal when anyone comes to altitude. Sleep is not going to be the same, and it takes a couple weeks for, actually, your sleep to adjust. But if it’s really interfering, and things are just not going well, we should take a look or consider whether that child is doing okay at altitude.
The other children who should not come to altitude are children who have a cardiac shunt with increased blood circulation in the lungs. That could really put them at risk for HAPE, and children with sickle cell disease. That can be really a crisis, even at altitudes as low as Denver, can cause a problem. So you need to be in touch with someone experienced with your condition if you want to travel with those conditions.
I have read in … articles by Peter Hacket and the other altitude experts not to bring children who are less than six weeks old up to altitude. Here’s the issue: you have a family wedding, everyone’s going there, you want to bring your new baby, they’re probably going to do fine. So I would say, just know where your local pediatrician that you can call anytime day or night is, and that baby will probably be fine.
Dr. Brent: Would you say the same for premature infants?
Dr. Chris: Premature infants, they are probably going to be okay. Once again, we have babies who are born in Denver and come home a few days or a few weeks into their early life experience, and we just check their oxygen in the office, or we can send a respiratory therapist from the oxygen company to their house to check their oxygen. And that is the best way to really keep track of what’s going on. Because babies are used to being in a low-oxygen environment. Remember, the uterus, the womb is like Mt. Everest. The oxygen saturation is 40 – 60%. So they don’t tell us that they’re having oxygen problems. They’re not breathing hard, they’re not retracting, they’re not coughing. They’re just mellow, but they may not be feeding well, so we want to check their oxygen by measuring it.
Right now we don’t have inexpensive ways of measuring oxygen in infants less than one year, but I’m sure that’s coming through very soon. The Owletis out there, we haven’t found that really reliable at high altitude. But we will be able to measure babies’ oxygen in our office, and sometimes, we will send families home with one of our infant pulse oximeters if we have concerns, and it’s night-time or weekend, and we can spare that piece of equipment.
Dr. Brent: I know we’ve talked about HAPE. Let’s talk a little bit about HACE, or High Altitude Cerebral Edema, which my understanding is just a part of the spectrum of acute mountain illness where you get some vaso-dilation going on in your brain and this can be even worse. How do you evaluate and then treat patients, especially kids you think may have some HACE?
Dr. Chris: So, diagnosing HACE in children, I don’t even know of a case. Because it mostly occurs above 15,000 to 17,000 ft. That is the flurid adult onset where they have trouble walking, talking, thinking, and you’ve got to get them down the mountain as soon as possible. However, the acute mountain sickness HAPE and HACE spectrum, it’s probably a continuum.
So there’s recently an article in the Journal of High Altitude Medicine and Biology or on the Cerebral Volume. And some people have more or less space around their brain. So does their brain expand under the influence of high carbon dioxide from increased ventilation or low oxygen, and that causes the headache and the nause and the vomiting, and is that an early spectrum of HACE that you can treat with oxygen? Babies who are very fussy, just can’t calm them down, just not eating: are they having a form of Cerebral Edema, that they would feel better with oxygen? We really don’t know, but those are things that there are a lot of research going on and providers should think about when somebody gives us a call or comes through the door with their child.
Dr. Brent: That’s good to know. And I know that you have your own practice here and specialize in taking care of kids, so let’s switch gears a little bit to kids who actually live at altitude. There’s so many problems I know at altitude. I think some of the smallest babies in the country are born in Leadville, CO. So how do you handle some of these kids? What are the problems you see? Is it worth the tradeoff to have a small baby who may not grow so well, but to live in the splendor of Colorado?
Dr. Chris: Well I just came back from the Chronic Hypoxia Conference in La Paz, Bolivia, where there were researchers from sixteen different countries, and one of the things that I learned there is that one reason that newborns can tolerate hypoxia during a difficult birth or resuscitation is because they’re coming from a chronic hypoxia environment. And their metabolism and their chromosomes and mitochondria are all switched on to a low-oxygen environment. And that helps them during the first couple weeks of life. So we actually say that probably the detrimental part of living at high altitude is more than counter-balanced by the increased health that we have, decreased myocardial infarctions, decreased strokes, longer active lives. But specifically in our newborns, they have decreased birth weights of about one ounce per every thousand feet of elevation. So our newborns are more likely to be 5.5 to 6.5 lbs. rather than 7.5 to 8 lbs. And about one third to a half of our newborns go home on oxygen based on pulse oximetry studies in the nursery that are less than 90. The Heart Association or the cardiac screening is not even done in our nursery. We are … the exception of the world, because we would have to do an echo- on every baby that we see. So most of these babies go home on oxygen, but I see them in the office when they’re three or four days old, another half of them their oxygen is fine and we tell the parents, “Okay, you can have them off oxygen, but we’ll check them one more time at two weeks before we have the oxygen company pick up the tanks.” So I very rarely have children, newborns, that are on oxygen for more than two weeks. That being said, nobody really knows what’s normal. If I have a child living at 11,000 ft., should that baby be held to the same standard as the kids in Kremmling at 8,000 ft.? Or in Frisco at 9,000 ft.?
We are planning a newborn oximetry study, and we’re in contact with some of the medical device manufacturers to try and get some equipment loaned, so that we can send this home with parents and find out what is normal, and establish our own normal. My normals are based on 19 years of clinical experience. If a baby meets 89 to 90 in my office during a clinical exam while they’re quiet or sleeping or breast feeding, I will tell the parents they don’t need oxygen.
The concerns we have is if the baby is at home for long period of time with low oxygen, the changes that are supposed to take place in the heart and lungs, such as the closing of the PDA and the decreased muscular lining of the pulmonary arteries may not proceed the way they are supposed to. And that process can take up to four months. So that’s why we don’t want to leave our infants with oxygen below 89 for long periods of time. We’re not worried about a few days or a few hours, the oxygen tank runs dry or the canula falls off. We’re not worried about brain damage.
We certainly know … — I’ve been a pediatrician for 40 years — my first 20 years as a pediatrician where we would have parents who refuse surgery for their cyanotic children, and they’d be going to second grade and you wouldn’t know there was anything wrong with their brain, they’d be blue as could be. So those are the concerns that I must address with all parents, because they are going to be terrified about this.
The next thing that is going to cause an issue with these newborns is the grandma in Florida is going to absolutely freak out that her little grand-baby is on oxygen because nobody else in the world understands our situation. We have 30,000 people living in Summit County with 5,000 in each of the surrounding counties, and another 60,000 in Eagle county. Outside of that, there aren’t any communities in North America at this high elevation. So we are the only ones who really have to deal with this. The rest of the doctors and family members are totally mystified by what we’re doing.
The second thing is, not only are they born a little smaller, but we have twice the number of children who are below the normal percentiles on the WHO and CDC growth charts during the first two years of life. So instaed of three percent, we have seven percent. What that tells me is that the whole growth percentile thing is probably shifted downward. We have just analyzed 30,000 data pieces from growth charts from our clinic and the Community Care Clinic in Summit, with the help of the Minnesota Department of Epidemiology, and we are hoping to publish our own unique high altitude growth charts.
The reason this is important is because when our children come down to see a specialist at Children’s Hospital, they get told that they are not feeding their children, and that their children need to see an endocrinologist and have $2000 worth of tests done. Whereas, after my first five years as an experienced pediatrician working with feeding specialists and OT’s watching these kids grow, I decided these were normal, healthy mountain kids. Very important information.
Dr. Brent: And so, Chris, do these kids eventually catch up by the time they’re 8, 10, 12, 16, adults?
Dr. Chris: They catch up by the time they’re 2.
Dr. Brent: By the time they’re 2, perfect. So they’re not shorter than the rest of the kids in the country.
Dr. Chris: Not at all.
Dr. Brent: Just wanted to make sure. Otherwise you might not have such a huge influx of people coming in to Colorado. Anything else you’re concerned about or have to do anticipatory guidance for for kids born in Colorado?
Dr. Chris: In our population, we also see children who have Re-entry HAPE. So during spring break, they go down to visit grandma in Florida, and when they come back they have a cold, and that night, the mom calls me and says, “Oh, he’s coughing and he sounds really congested.” Well, that’s my clue that probably lungs are filling with fluid and that child needs oxygen. So we want people to be aware of that who do live at altitude.
The other thing that I’m just starting to explore is we had a case of a post-traumatic HAPE, where a student from the mountains was going to school in Denver and was hit by a car and had three broken ribs. He was hospitalized in Lakewood overnight, he had a scalp laceration, he had x-rays and CAT scans that did not show anything in the lungs. So he left the hospital at noon the next day with an O2 sat of 94. By 10 ‘o clock that night, his oxygen was 49. He had rails in both lungs, however the x-ray did not show fluid. The emergency room doctor in Summit diagnosed Re-entry HAPE, he was sent back down to Lakewood. He was on 20 liters of oxygen. He was in the ICU, he had a CT scan, which also read as normal, and by the morning, he was on 4 liters of oxygen.
Now, to me and to that ER doctor, the only thing that this could be is HAPE. However, once again, I can’t get this past the high altitude experts and pulmonologists with normal imaging. So I’m throwing a question out there. We need to be sensitive to and start to discover whether there are cases of post-surgical, post-traumatice HAPE. I hear the stories, and that brings us to the blog.
The blog at highaltitudehealth.com. So as I said, it took me nine years to get my first paper published. However, in the blog, you can publish anecdotal and personal stories of your experience with altitude. And it’s out there for people to read and say, “Oh! Maybe that’s what’s happening to me or to my child. Or maybe I should know about that before I make my trip to altitude. Or maybe I should know about that with these children who are coming down to see me from altitude.”
So I highly recommend that anyone who’s interested or visiting or living at altitude read our blog, highaltitudehealth.com. And you can get some ideas and you can make some comments and give us your ideas. And that can lead to further study and research and help us understand these situations.
Dr. Brent: That is a wonderful resource for everyone, and I would hope that our listeners and our Charting Pediatrics family all over the world listen to this. There are so many children that I see in the ER, and when I mention that I think that they have some kind of acute mountain illness, they look at me like I’ve got a fork coming out of my head. They’ve never heard the concept, and … like, “How can my kid be fussy and not eating and not sleeping, and why …?” And they don’t know that. So I think the more we can get the information out there, that would just be wonderful. So glad you’re doing this. I do think that, personally, I get a little bit of re-entry illness everytime I drive from Denver to Vail. I come down Vail pass, I get a little queasy, I get a little headache, and it takes me … a day or two to get back on track, then I’m right back down to Denver and all my symptoms are gone. So, crazy that after 15 years, I still have my little own issues with altitude in this …
Dr. Chris: Well, I have an interesting anecdote that I haven’t put on the blog yet. I made a presentation to our first line, first-responders, and someone came up to me and said that he works in Denver, so he reverse-commutes. And every time he came home on weekends, he would be sick. His primary care physician in the mountains put him on acetazolamide. And that took care of his symptoms. So he’s kind of on chronic acetazolamide, which we’re seeing more and more that this is a very safe medication that you can take when you need it. It doesn’t have to be before you arrive, it can be after you arrive, it can be five days after you arrive. If you’re not sleeping well, you can try this. The only side effects are tingling in the hands and feet, and a very bad change of taste for carbonated beverages.
Dr. Brent: That could be a good thing. I think, I know when my physician talked to me about Diamox, she had mentioned that some of the side effects are headache and GI distress, which is what I had anyway, and I thought, well, why would I want to take a medicine that the side effects are the same as the disease. But you’re saying you don’t see that very often.
Dr. Chris: I have not seen that at all.
Dr. Brent: Excellent. And no issues with kids either. Do you think that, when I see kids in the ER who have some acute mountain illness that I should be starting Diamox at that low dose? The 5 mg per kg on those kids as well?
Dr. Chris: Yes, it doesn’t hurt. And it’s definitely empowering to parents. Just like, for parents to know that they can call me on my cell phone. For parents to know that there is a medication they can give. They may not need to give it, like we give anti-biotics and say, “Okay, if their ear pain gets worse, start the anti-biotic.” More than half of them will never give that anti-biotic. But having the ability to treat your child, you feel so helpless when people are uncomfortable or sick or suffering around you, but having the ability to give them a very safe medication or call somebody for information can really give them a lot of peace of mind.
Dr. Brent: And so my overall message I’m getting from you is really one of empowerment for families taking care of their kids, that there are so many solutions. They can keep their vacation. But the mainstay is oxygen, and in your back pocket you have a little Diamox, and maybe a little Zofran.
Dr. Chris: Yep. And ibuprofen.
Dr. Brent: And ibuprofen. Excellent. One quick question: Is there ever a role for inhaled steroids if there’s some inflammation going on ? You talked about a trial of albuterol.
Dr. Chris: My families whose children have had recurrent HARPE have told me that they do not feel that adding steroids has helped. Now, that being said, all the kids — and I see 30 – 40 cases per year of mountain resident children who have a hypoxic episode during an illness and have to use home oxygen — if they have more than one episode, we do refer them to the cardiologist that comes quarterly to our office to have an echo- at high altitude to rule out any hidden cardiac shunt that could predispose them. But many of these parents will self-refer to one of the many fine pediatric pulmonologists at National Jewish or Children’s Hospital. And when they go there they will inevitably be told that their child has asthma and needs to be on inhaled steroids. They will be on inhaled steroids for a year, and they will not have any more episodes, which they were not going to have anyways. So, there you go.
Dr. Brent: I love that answer.
This has been such a wonderful talk. In closing, I love to ask this of each of our guests here: What is the most rewarding aspect of your practice?
Dr. Chris: My relationship in the community and with the families is so special, because of the small size of our community. I am able to give my cell phone to the families, and I only get a few calls a week. I might be in my office, suturing up a three-year-old and save them the cost of going to the ER, you know, once a month or every second month. But because of this low-oxygen issue, I just feel that it’s important that we touch bases and have access to understanding what’s going on with both children and adults in our community. And I also have appreciated texting, because it’s less invasive, so it’s something that’s not urgent, like a rash or an eye discharge, my patients will text me or sent me pictures. and we are having a Telehealth app coming into our practice too, so that will make it more HIPA-compliant, and more comprehensive care for the Ebert Family Clinic.
Dr. Brent: Well, hopefully we can get all of you at the Ebert Family Clinic on Tiger Connect, and solve all your problems at once. But, Dr. Ebert-Santos, it has been such a pleasure to have you on the podcast today. Your passion is palpable, what you do has such a wonderful impact on kids and their families, not only in Colorado, but those visitors who can salvage their vacation to our beautiful state because of the the things you do. So on behalf of ChartingPediatrics, thank you, and hopefully we can have you on for a follow-up episode sometime in the near future.
Dr. Chris: Yes, when we finish these research studies on newborn hypoxia and normal oxygen values in adults, we’ll have more to tell you.
Dr. Brent: Well, you are on, and we can’t wait. And until next time, keep on keeping kids safe out there!
What is a normal overnight oxygen saturation for a child? This question is asked frequently by parents who have a child that may be requiring oxygen after evaluation. As healthcare providers working at various altitudes and caring for children, knowing the change in baseline oxygen saturations when at different altitudes is key to educating patients. There are physiologic changes that result in transient changes in respiratory rate and volume while sleeping which will be discussed before exploring nocturnal oxygen needs at sea level versus needs at high altitude in healthy children.
To begin, I will define a few terms that may not be familiar, but may be used when discussing oxygen needs. Oxygen saturation is defined as the amount of oxygen bound to hemoglobin in the blood, expressed as a percentage of maximal binding capacity.1 The simplest and most non-invasive way to obtain this information is through a pulse oximeter, which is placed on the patient’s finger, toe, or ear when vital signs are being taken. Oxygen saturation is known as the “5th vital sign” and tells medical providers whether or not a patient is delivering enough oxygen to their body. Hypoxemia is defined as insufficient oxygenation of the blood.2 There are multiple causes of hypoxemia, however we categorize hypoxemia as an oxygen saturation of less than 90 percent on a pulse oximeter. Finally, we use the term desaturation to describe a patient whose oxygen saturation continues to go below expected values.
In healthy, full-term infants, sleeping approximately 16 to 18 out of 24 hours is expected. A majority of their sleep cycle is REM and occurs when they fall asleep, with shorter duration of NREM sleep. As the child’s nervous system matures, there will be predictable changes in their sleep cycle, which will be more similar to a child or an adolescent. In children and adolescents, NREM is entered when they initially fall asleep, and accounts for approximately 75 percent of total sleep time, with alterations every 90 to 100 minutes of REM and NREM. In addition, there is a progressive increase in REM in the final third of the night.3 Understanding these cycles, what occurs during these cycles, and how they change over time are important in understanding the physiological changes (Table 1) that occur while you are sleeping.
The physiological changes that we are focused on are decreased respiratory rate and decreased respiratory volume, which are seen in NREM and in the phasic stage of REM. In infants, periodic breathing is also an observed pattern of breathing that is expected after the first 48 hours of life until about 6 months of age. Periodic breathing is recurrent central apnea interrupted by breathing efforts. This topic will further be discussed in the high-altitude study, as these episodes are more common at high altitude.4
In a study conducted at sea level in Brisbane, Queensland, Australia, 34 healthy term infants were studied at 2 weeks, 3, 6, 12, and 24 months in a prospective longitudinal cohort study. The study mentioned that there was limited data on reference ranges for normal nocturnal oxygen in infants, but that they aimed to develop a cumulative frequency (CF) reference-curve. This curve may be used as a tool to compare a child’s nocturnal oxygen saturation to see if the infant falls within the range for infants that are similar in age (Figure 1). Overall, the median nocturnal saturation was between 98 and 99 percent, for infants living at sea level.6
In an additional study, conducted at high altitude in Bogotá, Colombia, 122 healthy full-term infants were studied in 4 various groups. These groups were coupled differently and were only monitored until 18 months of age. The groups were <45 days, 3 to 4 months, 6 to 7 months, and 10 to 18 months. In addition to these groups, 50 infants completed three overnight PSG studies and were analyzed as a longitudinal sub-cohort.
In this study, their overall data was presented differently and they also looked at SpO2 during wakefulness and respiratory events, which are more likely to occur at higher altitudes. An interesting finding, that was not present in the study at sea level in patients of similar size, age, and weight, was the increase in total, central, and obstructive apneas. In addition, there were also very high frequency oxygen desaturation events that again are not seen when living at lower altitudes. These events were reported as normal in infants living at high altitude. Overall, the median SpO2 was between 92 and 94 percent at high altitude.7
To conclude, the median oxygen saturations at sea level were between 98 and 99 percent and between 92 and 94 percent at high-altitude. This said periodic breathing, which is normal until six months of age at any altitude, causes transient desaturations and are more common at high altitude. Apneic events are more commonly seen in infants at altitude, but are considered normal. These studies have offered reference ranges and tools to better aid clinical judgement when caring for a patient that may require oxygen.
1. Oxygen saturation. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. (2003). Retrieved March 23, 2019, from https://medical-dictionary.thefreedictionary.com/oxygen+saturation.
2. Hypoxemia. The American Heritage® Medical Dictionary. (2007). Retrieved March 23, 2019, from https://medical-dictionary.thefreedictionary.com/hypoxemia.
3. Wise, M., and Glaze, D. (2018). Sleep physiology in children. UpToDate. Retrieved March 23, 2019, from https://www-uptodate-com.ezproxy.stfrancis.edu/contents/sleep-physiology-in-children?search=sleep%20physiology%20in%20children&source=search_result&selectedTitle=1~134&usage_type=default&display_rank=1#H4.
4. MacLean, J.E., Fitzgerald, D., & Waters, K. (2015). Developmental changes in sleep and breathing across infancy and childhood. Pediatric Respiratory Reviews, 16(4), 276-284.
5. Hanyang Medical Reviews. 2013 Nov;33(4):190-196. https://doi.org/10.7599/hmr.2013.33.4.190.
6. Terrill, P., Dakin, C., Hughes, I., Yuill, M., & Parsley, C. (2015). Nocturnal oxygen saturation profiles of healthy term infants. Archives of Disease in Childhood, 100(1), 18-23.
7. Duenas-Meza, E., Bazurto-Zapata, M., Gozal, D., Gonzalez-Garcia, M., Duran-Cantolla, J., Torres-Duque, C. (2015) Overnight Polysomnographic Characteristics and Oxygen Saturation of Healthy Infants, 1 to 18 Months of Age, Born and Residing at High Altitude (2,640 Meters). Chest, 148(1), 120-127.
The September 2018 issue of the Journal of High Altitude Medicine and Biology has an article reviewing statistics on newborn health in the Mountain Census Division: AR, CO, ID, MN. NM NV, UT and WY. The lead author, Robert Levine and his coauthors found that newborns in this region have “by far the lowest infant mortality rates for respiratory distress.” Conversely, there is a higher incidence of intraventricular hemorrhage, or bleeding in the brain, not caused by trauma. This can be a complication of prematurity.
The authors analyzed about 70 million births and 12,000 deaths in over 3000 counties between 2007-2015. They compared maternal education, age, and marital status. The mean elevation of the mountain division counties is 5,725 feet, with the mean for the rest of the US being 2,500 ft. Colorado ranges from a low of 3317 ft to 14440 with a mean of 6800 ft. There were 30 counties above 8000 ft.
Their conclusion :”…we believe the most plausible interpretation of the present data is that they raise questions abut whether maternal residnce at high altitude has uniformly adverse health effects on infant mortality.”
In other words, maybe it’s not all that bad to live in the mountains!
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.