Category Archives: Altitude Science

WMS Blog entry No. 1: The Rule of 3’s and other pearls from the annual Wilderness Medical Society Conference 2020

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!

Mountain Kids are Smaller

How does living at high altitude affect the human body? It’s a complicated question that researchers have been trying to answer for years.

It takes two things to grow: adequate nutrition and the body’s ability to convert calories into energy.  Observations over 20 years at the Ebert Family Clinic suggest that the decreased oxygen levels at altitude may interfere with optimal utilization of calories or decrease appetite and intake in small children.

After opening her pediatric clinic in Frisco, CO in 2000, Dr. Christine Ebert-Santos noticed that children living at high altitude are smaller than average. Dr. Chris and Meredith Caines Pollaro, an occupational therapist with expertise in feeding and growth in children, organized a group for parents of underweight children but did not find any consistent abnormalities. After this, Dr. Chris decided that smaller growth might be a normal pattern for little ones at altitude. The children were otherwise healthy, with nutritional analysis showing adequate intake, and no signs of endocrine or gastrointestinal problems.

Graduate student Aaron Clark reviewing high altitude growth charts with PA student Laura Van Steyn and Dr. Christine Ebert-Santos.

Research on growth in children at altitude is sparse. So, in 2009, Dr. Chris recruited her daughter Anicia Santos to launch a detailed data analysis.  Anicia worked with one of her math professors at the University of Colorado to convert the data into a unique growth chart for altitude which demonstrated the downward shift. Twice the number of infants and toddlers had weights below the 3rd percentile of the World Health Organization growth charts than at lower altitudes. Heights were also decreased. After years of gathering data, Dr. Chris and Anicia are getting ready to share their findings with the help of Logan Spector, PhD and graduate student Aaron Clark.

Spector, chairman of the department of epidemiology at the University of Minnesota, was concerned about his two nieces who lived in Summit County who were not fitting into the “normal” growth pattern. This sparked his interest in Dr. Chris’ research. He was able to recruit Clark to take on the project.

In the first study of its kind in North America, the growth charts of 970 kids living in Colorado’s high country are analyzed. With over 9,000 pieces of data, one thing is clear. From birth to 18 months of age, children living at altitude weigh much less than the average child. Length is also considerably decreased, though the weight discrepancies are more drastic. These findings were studied extensively and found to be statistically significant. Using the generalized estimating equation (GEE), Clark was able to analyze the data in a non-linear way. This compensates for correlated data. Clark created density graphs for both male and female children to depict these findings (see figures). When the graph line is fairly close to 1 on the y-axis, or a straight line across the top, this means there is little difference from the standard growth chart (age 2-18). The farther away from 1 on the y-axis, the more significant difference there is compared to standard growth charts (age 0-2).

There is no denying that something is causing these high-altitude children to fall off of the growth charts. The next logical question would be, what are the effects of this smaller growth rate? Initial research shows that children at altitude are catching up on the growth curve by age two. There does not appear to be any long-lasting deficits from the initial smaller growth.

After combing through research articles, a new study from Ladakh, India also displayed a correlation between children living at high altitude and smaller size. Specifically in Colorado, another study shows lower birth weights at high altitude, however, it does not follow the growth patterns of the children over time.

From what this research shows,  a unique growth chart for children living at high altitude would be helpful. A new growth chart would account for the variations in size seen at altitude. This could save thousands of dollars in unnecessary testing looking for underlying disease or endocrine deficiencies as well as the anxiety for parents being told that their child has failure to thrive or is not being fed. Instead of being concerned when a child falls low on the growth chart, one might expect to see smaller children at altitude.

There is still much research to be done in this field. Hopefully, this study will serve as fuel for future studies.

Laura Van Steyn is a 3rd year Physician Assistant student studying at Midwestern University in Glendale, AZ. She graduated from the University of Colorado in Boulder with a degree in integrative physiology. After that, she worked as a CNA at Littleton Adventist Hospital prior to starting PA school. She hopes to work in women’s health or dermatology after graduating. During her six weeks at Ebert Family Clinic, she has joined Dr. Chris for numerous hikes and has truly enjoyed escaping the Arizona summer heat!

References

Yang, W.-C.; Fu, C.-M.; Su, B.-W.; Ouyang, C.-M.; Yang, K.-C. Child Growth Curves in High-Altitude Ladakh: Results from a Cohort Study. Int. J. Environ. Res. Public Health 2020, 17, 3652.

Bailey, B.; Donnelly, M.; Bol, K.; Moore, L.; Julian, C. High Altitude Continues to Reduce Birth Weights in Colorado. Matern Child Health J 2019, 23(11): 1573-1580

COVID-19 Update: A Look at How the World’s Highest Altitude Populations Have Been Affected

As the gateway to Machu Picchu, the city of Cusco, Peru attracts over 3 million tourists from all around the globe each year. With this many people passing through the city, you can imagine why local residents feared the worst when the COVID-19 outbreak began. However, out of a population of approximately 429,000 people, the city has only four COVID-19 related deaths – three tourists who traveled to the area and one native with previous risk factors.

Machu Picchu

Machu Picchu, a UNESCO World Heritage Site, brings 3 million tourists from around the world to the Cusco region of Peru every year.

One death out of 196 confirmed cases for the city makes for a remarkably low fatality rate of 0.5% for the native population. Peru as a whole has a fatality rate closer to 3% with over 6,000 deaths, making it one of Latin America’s most affected countries. Many believe the fatality rate to be even higher as testing has not become widely available in the country.

To understand why Cusco is such an outlier when compared to the rest of the country, there are several factors to take into consideration. One of those factors that researchers haven’t quite been able to figure out, but believe plays a role, is altitude. The Cusco region of Peru sits at 11,152 ft elevation compared to the capital city of Lima that sits at only 512 ft elevation.

Research comparing the high-altitude regions of Tibet, Bolivia, and Ecuador has revealed similar trends. A study completed April 22, 2020 and published in the June 2020 scientific journal “Respiratory Physiology & Neurobiology” indicates that populations living above 9,842 feet elevation reported significantly lower levels of COVID-19 cases than populations living at lower elevations. The research showed the infection rates in the Andes Mountains of Bolivia were one third the infection rates the rest of Bolivia, and the infection rates in the Andes Mountains of Ecuador were one fourth of the rest of Ecuador. In both Bolivia and Ecuador, the areas with the highest concentration of COVID-19 cases were located at an elevation close to sea level.

At an elevation of 11,942 ft, La Paz, Bolivia is the highest capital city in the world.

Why populations living at higher altitudes are experiencing lower infection rates is still not well understood, but there are a few theories at play. It is hypothesized that people living at altitude are able to live in a state of chronic hypoxia, or a state of chronically low oxygen in the blood. Hypoxia is one of the conditions caused by COVID-19, and if a person’s body is already used to low levels of oxygen, their symptoms may not be as severe. There are other environmental considerations at altitude that may shorten the life-span of the COVID-19 virus, including high levels of UV radiation that can kill the virus, low barometric pressure that does not support the weight of the aerosolized droplets that the virus lives in, and dry thin air that does not support the transmission of aerosolized droplets.

However, as intriguing as the effect of altitude on COVID-19 statistics is, it is important to note that there are several other proven factors that come into play when looking at these populations. First, most high-altitude towns and cities tend to be rural. When population density per square mile drops, the rate of transmission of infectious diseases also drops – rural settlements allow for natural social distancing. Second, populations living at higher altitudes have lower rates of obesity and generally have better overall health. Living at high altitude causes a reduction in the hormones that signal hunger, leading to consumption of fewer calories. Additionally, completely normal daily activities in a state of chronic hypoxia due to low levels of available oxygen in the air raises the body’s resting metabolic rate, leading to burning more calories. The healthier a person is prior to contracting an illness, the more likely their body is to be able to fight it off successfully.

Research regarding how altitude affects COVID-19 transmission, infection, and recovery rates is ongoing. It may be too soon to tell exactly why or how altitude comes in to play, but early findings are suggesting that now is a great time to be a resident of the great Rocky Mountains – but then again, when is it not?

References

https://www.washingtonpost.com/world/the_americas/coronavirus-andes-peru-ecuador-bolivia-tibet-high-altitude/2020/05/31/0b2fbf98-a10d-11ea-be06-af5514ee0385_story.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7207123/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175867/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5094724/

https://en.wikipedia.org/wiki/Machu_Picchu#/media/File:80_-_Machu_Picchu_-_Juin_2009_-_edit.2.jpg

https://en.wikipedia.org/wiki/Machu_Picchu#/media/File:80_-_Machu_Picchu_-_Juin_2009_-_edit.2.jpg

Megan Schiers is a 3rd year Physician Assistant student studying at Midwestern University in Glendale, AZ. She graduated from Idaho State University in Pocatello, ID with a Bachelor of Science in Dental Hygiene and worked as a dental hygienist in Strasburg, CO for two years prior to starting PA school. She is passionate about increasing access to healthcare in rural areas and hopes to specialize in emergency medicine or cardiothoracic surgery following graduation this fall. During her six weeks in Frisco, CO, she has enjoyed hiking in the beautiful mountains, camping at Camp Hale Memorial, visiting Maroon Bells, and checking out Black Canyon of the Gunnison National Park.

COVID in Colorado Update: Reasons high altitude residents may be less susceptible

Last week we were privileged to have a Zoom discussion with two high altitude experts from the Instituto Pulmonar Y Patologia de la Altura (IPPA) founded in La Paz,  Bolivia in 1970. Dr Gustavo Zubieta-Calleja and Dr. Natalia Zubieta-DeUrioste answered our questions about their recently published article, Does the Pathogenesis of SAR-CoV-2 Virus Decrease at High Altitude?. They and the seven  coauthors presented data comparing COVID cases in high altitude areas of China, Bolivia and Ecuador showing a marked reduction in numbers compared to low altitude areas in the same countries, with dramatic, colorful topographic maps.

Drs. Zubieta-Calleja and Zubieta-DeUrioste and their colleagues theorized four reasons why altitudes above 2500 m could reduce the severity of the corona virus. (Note: Frisco, CO is at 2800 m, Vail 2500 m). As described in their previous paper published in March, the intense UV radiation at altitude as well as the dry environment likely reduce the viability of the virus in the air and on surfaces.

Dr. Zubieta-Calleja on a Zoom chat with Dr. Chris explaining a chart comparing UV exposure in La Paz, Bolivia (top line) and Copenhagen, Denmark (bottom line).
Dr. Chris with Dr. Gustavo Zubieta-Calleja and other altitude experts from the Hypoxia Conference in La Paz on the Camino Chacaltaya, which reaches an elevation of 17,785’/5421 m.

The low barometric pressure causes air particles to be spaced more widely, which would also decrease the viral particles inspired with each breath, reducing the severity and frequency of infections.

Furthermore, residents accustomed to chronic hypoxia may express reduced levels of angiotensin converting enzyme 2 (ACE2) in their lungs and other tissues. This enzyme has been found to be the entry path for the corona virus into cells where it replicates. Finally, the normal adaptation and acclimatization of populations with prolonged residence above 2500 meters may reduce the severity of the disease in individuals, and reduce mortality. This includes increased ventilation, improved arterial oxygen transport, and higher tissue oxygenation mediated by increased red blood cells produced under the influence of erythropoietin, which could be explored as a possible therapy.

Dr. Zubieta-Calleja with statistics reflecting the number of COVID-19 infections at different elevations in Bolivia. Note the most infections occur at a lower elevation.

As we stated in our interview quoted in the Summit Daily News March 17th, none of these factors can be relied upon to protect every individual. Therefore it is important to continue frequent hand washing, wearing masks, social distancing, and avoid touching your face.

COVID in the Mountains: What are the Risky Situations to Avoid as We Start Leaving Our Homes?

We are on the back slope of the epidemic, according to University of Massachusetts Dartmouth Professor of Biology Erin S. Bromage, Ph.D. He explains what to expect and where not to go in an article this week which was cited in the New York Times: The Risks-Know Them-Avoid Them. The bad news is that the back slope can have as many deaths as the upslope.

The good news is that you don’t get COVID outdoors, as long as you are not standing close to someone who might have the virus for a period of time, perhaps over ten minutes. Bromage reviews a series of epidemiologic studies tracing the spread of the disease in situations including standing outside talking to someone (one case), church choir practice (45 of 60 infected, 2 died), indoor sports, specifically a curling tournament in Canada where 24 of 72 attendees became ill, birthday parties and funerals (high rate of infection and many deaths related to hugging, kissing and sharing food), grocery stores (safe for shoppers but employees get infected), and restaurants (50% infection rate after sharing a meal with nine at the table). He also reported details about the spread of disease at meat packing plants, a call center and a medical conference.

The risk of infection increases with exposure to a larger number of virus particles over a longer period of time in a smaller space with poor air flow. This is why shopping and outdoor activities are not likely to be dangerous. Breathing releases a small number of virus, between 50-5000 droplets per breath. Talking expels more and  singing is definitely a means of spreading virus. A single cough releases 3000 droplets traveling 50 miles per hour, mostly falling rapidly to the ground. In contrast a sneeze may release 30,000 droplets at 200 MPH, many of which are smaller and stay in the air longer.

Dr. Bromage writes that 44% of infections come from people who have no symptoms at the time.  The virus can be shed up to five days before a person becomes ill. Most people contract COVID from a family member who brings it home. Children are three times less likely to become ill but three times more likely to spread the virus.

I wondered if the lower barometric pressure at altitude could cause viral particles to be less compact. I called Peter Hackett, MD of the Hypoxia Institute in Telluride and he agreed that theoretically the less dense air would not carry as many particles. We also discussed antibody tests, which are still experimental, not recommended and difficult to interpret. The population screened in Telluride showed a 0.5% positive rate, but when a disease has a low prevalence there are more false positives. They did blood tests on some 5,000 people early in the outbreak. They were not able to repeat the serology due to staffing problems at the lab where many technicians contracted the illness.

My advice is to wear masks anytime you are out of the house, except if you are biking, hiking, running where the viral particles will be dissipated rapidly. Wearing a mask during these activities is still a kind gesture  to reduce the anxiety of others. Continue with frequent hand washing, avoid touching your face, practice social distancing, and when the churches reopen we should hum instead of sing.

COVID VS HAPE: Experts Analyze Effect on Lungs

Dr. Chris with Dr. Eric Swenson from the University of Washington

An article published yesterday, April 13, 2020 in the Journal of High Altitude Medicine and Biology clarifies misconceptions in the media comparing high altitude pulmonary edema (HAPE)and COVID lung injury. The six authors include two critical care pulmonologists from the University of Washington: Andrew Luk MD and Eric Swenson MD, as well as Peter Hackett MD of the Hypoxia Institute in Telluride and the University of Colorado Altitude Research Center. Dr. Swenson is the editor of the journal and has given presentations in Summit County on altitude. Both Dr. Hackett and Dr. Swenson personally communicated with Dr. Chris yesterday.

Dr. Chris with Dr. Peter Hackett of the Hypoxia Institute in Telluride, CO

Severe viral pneumonia, as seen in COVID-19, can cause Adult Respiratory Distress Syndrome (ARDS) leading to respiratory failure and the need for ventilator support. As with HAPE, this is a form of non-cardiogenic pulmonary edema, where the air sacs in the lung fill with fluid due to conditions not related to heart failure, the most common cause of pulmonary edema. Other causes include bacterial pneumonia, near-drowning, nervous system conditions, re-expansion, and negative pressure edema. Radiographic findings are similar in all these cases with diffuse bilateral densities in the lungs. All these patients have severe hypoxia.

At altitude, hypoxia can lead to uneven pulmonary vascular constriction, (hypoxic pulmonary vasoconstriction or HPV). In the areas with the highest pressure, fluid leaks from capillaries into the alveoli. With COVID, alveolar inflammation reduces the protein surfactant that maintains expansion of the alveoli. The alveolar collapse causes hypoxemia, low blood oxygen. Severe viral and bacterial infections also cause inflammation in other organs, such as the liver, kidneys, and brain, which is not seen with HAPE.

Medications used to treat HAPE are not likely to be useful in treating COVID pneumonia and may have harmful effects such as increasing perfusion to damaged areas of the lung that are not oxygenated.

Both these conditions likely have large numbers of patients with mild symptoms who recover without seeing a medical provider. However, both HAPE and COVID can cause a sudden, rapid deterioration with severe hypoxia and death.

ACCESS TO A PULSE OXIMETER TO TRACK OXYGEN SATURATION IS VITAL.

Oxygen levels below 90% merit medical attention. Pulse oximeters can be purchased online, at drug stores, or at Ebert Family Clinic.

COVID Vs. HAPE: Frontline Theories on Treatment

A good friend in Hawaii recently sent me a YouTube video referencing Dr. Cameron Kyle-Sidell, a critical care and emergency room physician at Maimonides Medical Center in NYC.  Dr. Kyle-Sidell was discussing his findings while working with COVID-19 patients in NYC and compared those findings to altitude sickness. I did a search and found he had posted several videos on social media comparing Acute Respiratory Distress Syndrome (ARDS) in COVID-19 patients to altitude sickness and reconsidering how these patients are treated. Altitude sickness is something I see and treat frequently here in Summit County. Based on the similarities between the two conditions, the same treatment for altitude sickness and high altitude pulmonary edema (HAPE)[1] may be beneficial to COVID-19 patients.

In an interview with Dr. John Whyte, Dr. Kyle-Sidell described the acute ARDS he is seeing in COVID-19 patients as atypical and not responsive to standard treatment, specifically in regards to ventilator use and settings. He describes some of his patients as alert, talking in full sentences, and not complaining of shortness of breath but have oxygen saturation levels in the 70s (John Whyte & Cameron Kyle-Sidell, 2020). Normally, that is not the case when a person has an O2 saturation[2] in the 70s and is in respiratory distress. However, this is not abnormal in patients with altitude sickness and HAPE. There are certain protocols in hospitals regarding when to intubate a person and to put them on a ventilator. According to Dr. Kyle-Sidell, these protocols apparently aren’t always helpful for COVID-19 patients with ARDS, and can at times be harmful.

The similarities between findings with COVID-19 and HAPE are remarkable. These similarities include: hypoxia (low oxygen levels), low CO2 (carbon dioxide) levels, tachypnea (rapid respiratory rate), patchy infiltrates seen on chest x-ray, bilateral ground glass appearing opacities on chest CT, fibrinogen levels/fibrin formation, aveolar compromise[3], decreased Pao2:FiO2 ratios[4], and ARDS in severe disease (Solaimanzadeh, 2020). Noting these similarities may be helpful when approaching treatments for COVID-19.  Acetazolamide (Diamox), Nifedipine (Procardia) and Phosphodiesterase inhibitors (Viagra, Cialis etc.) have been used in treating HAPE and could possibly be beneficial in treating COVID-19. For example, Acetazolamide potently decreases the constriction of small vessels in the lungs that contribute to fluid build up (edema) seen in both HAPE and COVID-19 patients (Solaimanzadeh, 2020).

In our house call practice, we treat quite a bit of altitude sickness due to our elevation here in Summit County. During the ski season, we may see 3-4 patients per month that develop HAPE. The majority of the time, these patients can be safely treated and monitored in their residence or hotel room. Treatment for both altitude sickness and HAPE consists of oxygen, usually 2-5 L/min via nasal cannula continuously while sleeping or resting. We also treat our patients with an injection of a steroid, Dexamethasone. We closely monitor them and may repeat the dose of Dexamethasone or prescribe an oral steroid. These patients usually see some improvement by the next day and significant improvement when they descend in altitude. I have read recommendations for and against steroid use with COVID-19.  More studies need to be done, which I will be following closely as future recommendations may change how I treat HAPE when there is also a suspicion of COVID-19.

The key to treatment is oxygen! We’ve seen patients with O2 saturation levels in the 40s and 50s and lungs that sound like a “washing machine”, as Dr. Gray, has described it (in a previous Doc Talk article). If we can get their oxygen saturation up into the mid 80s or 90s on 5L/min (of O2) or less via nasal cannula, typically, they can avoid an ambulance ride and emergency room visit. As Dr. Kyle-Sidell notes, many of the COVID-19 patients he sees are talking coherently and not in severe respiratory distress. A friend who is an EMT in New York described a man he recently transported to the hospital, in his 50’s, with presumed COVID-19. He had no respiratory distress, walking and talking coherently, no chronic medical problems but his oxygen saturation was in the 60s. He said they took him to the emergency room and he was intubated and placed on a ventilator. Apparently, this is a common occurrence from what he has seen. I am still amazed when a patient calls, gives me their address and directions to where they are staying and when I arrive, their oxygen levels are in the 40s. It is a very rare occurrence that I need to send a patient to the hospital, which they always appreciate. We monitor our patients very closely until their departure and have them call anytime, day or night, with any changes in condition.

Dr. David Gray, who started our business, has been treating these patients for over 18 years. He states that in a few of the HAPE patients that he has treated, including his own 13-year-old son, he has seen O2 saturations in the 30’s & 40’s. In these few patients, he was only able to get their O2 saturation up to high 60’s, low 70’s, on 5 liters. They were so much improved, clinically, that he accepted those levels. A large dose of Dexamethasone & 12 hours of rest, on nasal oxygen, resulted in marked improvement by the next day, every single time. His rule, as in patients with DKA, is “if the pathology didn’t happen rapidly, you don’t necessarily have to reverse it rapidly.”

Dr. Kyle-Sidell suggests not putting COVID-19 patients on ventilators based solely on numbers (John Whyte & Cameron Kyle-Sidell, 2020). Treating these patients with prone positioning, oxygen via nasal cannula, high flow on a non-rebreather mask or CPAP[5] along with careful monitoring and a little patience may be preferable to a ventilator (John Whyte et al, 2020). If a ventilator is needed, using less pressure to reduce lung damage and higher oxygen levels may prove to increase the likelihood of a better outcome (John Whyte et al, 2020). There is so much to learn about COVID-19 and how to treat it. Treating it as you would with HAPE is certainly something to consider. I appreciate providers who are sharing their personal experiences in treating these patients. As healthcare providers gain more experience treating this virus and share their experiences, protocols will change and I suspect ventilator use as well as the death rate will decrease.

[1] A complication of altitude sickness in where the lungs fill with fluid and small amounts of blood

[2] Blood oxygen level

[3] Damage to the tiny sacks in the lungs where gas exchange occurs

[4] partial pressure of arterial oxygen: percentage of inspired oxygen ratio used to determine ARDS and lung damage

[5] Continuous positive airway pressure

Danielle Shook MSN, NP-C is a board-certified Family Nurse Practitioner. She has been in nursing for over 27 years. She earned her Master’s Degree at University of Colorado, Colorado Springs through Beth El School of Nursing. Her nursing experience includes 10 years in Obstetrics and 7 years in Hospice home care. She has over 9 years experience as an NP which includes Family Practice at the Air Force Academy, Urgent Care, Acute and after hours care with the Army Premier Clinic as well as house calls.

References

John Whyte, Cameron Kyle-Sidell. Do COVID-19 Vent Protocols Need a Second Look? – Medscape – Apr 06, 2020.

Solaimanzadeh I (March 20, 2020) Acetazolamide, Nifedipine and Phosphodiesterase Inhibitors: Rationale for Their Utilization as Adjunctive Countermeasures in the Treatment of Coronavirus Disease 2019 (COVID-19). Cureus 12(3): e7343. doi:10.7759/cureus.7343


Doc Talk with Cardiologist Dr. Pete Lemis

Dr. Peter Lemis is a cardiologist in Summit County, CO. He sat down with us in December to share his experience treating heart patients in the mountains.

Summit County cardiologist Dr. Pete Lemis

I graduated medical school in ‘77, practiced internal medicine in New Rochelle, New York, the first county just north of the Bronx. Then I went to New Hampshire for three years. I was reading the New England Journal and saw an unexpected cardiology opening at Henry Ford Hospital in Detroit. Next I was in Pittsburg for 26 years practicing cardiology. Decided I wanted to retire to Colorado, so I built a vacation home here only to discover I didn’t have to wait to retire to move here, so I came five years ago. 

What is it about high altitude and the heart that makes it healthy for heart patients?

Summit is the fifth highest county in the US with the highest population of those counties. The 21 highest are all in Colorado. Lower air pressure means that although there is 21% oxygen in the atmosphere, there are fewer oxygen molecules. So every breath we take is giving us less oxygen, unless we breathe faster and deeper to make up for it, a natural tendency for people. They don’t even think about it. Some people have hypoxia without shortness of breath. Every once in a while, I’ll see a patient who moved to altitude for work or something, and they’re hypoxic. It is probably genetic that some people have a decreased central respiratory drive. 

These patients with low oxygen often are ordered to have an echocardiogram. When they first come up here, they usually won’t have pulmonary hypertension. For some, the decreased central respiratory drive develops not when they first move here, but years after they move here. They become more and more hypoxic without having the feeling of shortness of breath. They have the same physiological response that people with hypoxia get. Their pulmonary vessels are still being constricted, which is reversible if diagnosed and treated with oxygen supplementation during the first few years of high altitude living. If not treated they are likely to get scarring of their pulmonary vessels. The length of time for this to develop is different for different people, and is unpredictable.

For example, I had somebody just this week who’s been here about 2 years who has a resting oxygen saturation of about 82% at 60 years old. 

We can’t tell who is susceptible to this problem. There are likely some genetic factors involved. Dr. Johnson, who recruited me for my job in Summit County, has been here since 2008. He warned me about the issue of high altitude and hypoxia. Most doctors who are unfamiliar with life at high altitude think you adapt and that’s it. Dr. Johnson said to me, “wait three months and test yourself and your wife with an overnight oximetry to see if there’s hypoxia.” Based on that test I started using nocturnal oxygen and I sleep better when I use it. My wife doesn’t need it. Neither does her mother, who is 90 years old. Neither do my sons.

Awake, we’re able to maintain our oxygen levels, but at night when asleep most people who are here in Summit County have low oxygen. Hence my advice is to get a nocturnal pulse oximetry test. Low oxygen for several hours every night over the years can lead to pulmonary hypertension due to the narrowing of the pulmonary arteries. Then there is the question of what is normal: most high altitude studies were done in La Paz with indigenous, adapted populations as opposed to people living in the mountains of Colorado who have been here years or decades. (See what Dr. Chris has written on her collaboration with physicians and scientists in La Paz, Bolivia.)

We asked Dr. Lemis about arrhythmias at altitude. There are two categories-atrial (from the top chamber) and ventricular (from the bottom chamber).

Studies have shown that cardiac arrhythmias are increased initially, but people become acclimated after about 3 – 5 days and the risk returns to baseline. I don’t think these studies have been conducted over enough time. Hypoxia leads to an increase in arrhythmias. I see a lot of atrial fibrillation  and atrial flutter up here; plus, I send three to four patients a month for an electrical procedure to ablate some of the cardiac conduction pathways to get rid of their arrhythmias. Many patients experience relief from atrial arrhythmias when put on nocturnal oxygen.

JB is a 70 year old who has lived at high altitude for 14 years. He experienced atrial fibrillation several times after returning to Summit County from a trip to sea level. He wore a heart monitor for over a month to see how his heart was beating. He felt the atrial fibrillation was related to dehydration and has prevented further episodes, never needing a pacemaker or other treatment. Jim uses a device that monitors his oxygen and heart rate continually while he sleeps, downloading a written report in the morning.

Why do so many people who live up here have bradycardia?

I think because many are athletes. Athletes often have an efficient heart; I see just as many people who have tachycardia because they have low oxygen. Low oxygen causes higher levels of epinephrine. This stimulates their adrenal gland, which can increase their blood pressure. Many people have high blood pressure at high altitude because they have low oxygen. One of my criteria for testing someone for low oxygen at night is if they have high blood pressure.

Many people have central apnea during sleep at altitude caused by the brain’s blunted response to high CO2 and low O2. Similar to obstructive sleep apnea, this central sleep apnea can increase the risk of heart problems. Many people with obstructive sleep apnea here at high altitude need to have oxygen put into their CPAP machine so they get oxygen, rather than just air with continuous positive airway pressure.

There is less fatal ischemic heart disease up here. People tend to be healthier, more athletic. They’ve moved here for an active lifestyle. There’s less cigarette smoking, more exercise, generally better diet (not always), but people up here still have heart attacks. My impression is more of them survive their heart attacks because of their increased physical activity and healthy lifestyle. They have better collateral flow with more capillaries in the heart. They’re protected to some degree. The corollary to this is the fact that when visitors come here and have heart disease, I don’t think that their cardiologist back at low altitude understands high altitude risks and therefore are unable to provide appropriate medical advice. The same amount of exertion here is much harder on the heart, much more stressful to the heart, than it would be at low altitude. There’s something called a double product when you do an exercise test, related to blood pressure and heart rates. You get the same double product causing the same stress on the heart here as at low altitude, but it takes much less exertion to get to a specific double product. 

People who are accustomed to a certain work load at home come up here and try to do the same amount of exertion. If they have coronary artery disease, suddenly there is a middle aged guy with coronary disease having a cardiac ischemic event, perhaps even sudden cardiac death. 

Another important point is that people with known heart disease who live at low altitude, if they’re unstable at all, they shouldn’t be up here within three to six weeks of a heart attack. They should be able to pass a stress test at low altitude before coming to high altitude to visit.

Valvular heart disease patients who have not been treated with surgery, who don’t already live up here, shouldn’t come up here from lower altitude. People with heart failure can come up here if the failure is compensated.

For people who have trouble acclimating to high altitude in the short term, Diamox is quite useful. Using oxygen at night helps you acclimate as well. Diamox makes your blood a little acidotic which increases your respiratory drive.

Avoid alcohol when you first come to high altitude. Unfortunately people on vacation don’t do that. Alcohol is a respiratory suppressant. At high altitude the hypoxia and cold promotes diuresis, so people tend to get dehydrated. Anti-inflammatory drugs are useful in treating the acute altitude sickness for some people. During the first two or three days, try not to push your physical activity to the limits. Try to get a good amount of sleep.

I would say that I have way fewer heart failure patients [up here]. Because patients who develop advanced heart failure really do not do well here, so they tend to move away to lower altitude before that happens. I have younger patients as compared with my former Pittsburgh practice. I also have way fewer patients with COPD. Anything that causes chronic respiratory difficulties you will find a lot less of that up here. Plus, I’m working in an environment where there are less consultants. 

Back in Pittsburg, two thirds of my practice was taking care of patients in the hospital, so I would deal with patients who would come in with a heart attack, with a heart failure exacerbation, or other acute cardiac problem. Here in Summit County, those severely ill patients get transferred down to Denver, so I provide more in-office preventive or post-illness follow-up than I do care in the hospital. My patients who need advanced procedures (e.g. heart catheters, ablation for arrhythmias), I generally send them down to our sister hospital (St. Anthony in Lakewood). 

The cardiac surgeon who will do the bypass surgery usually knows that the patient returning to the mountains will have to be on oxygen for two weeks after surgery.


Aconcagua: an Athlete/Medical Scientist’s Narrative in Symptoms

“Day 10: I walked for maybe an hour up to Camp 3 (19,258’/5870 m) from Camp 2 (18,200’/5547 m). I became the slowest person. I had tunnel vision. It was bad. It took a lot of willpower. I do a good job of not telling people how bad I really feel. After about a mile, I told them I had to stop, and me and Logan turned around. We had that conversation,

‘I don’t think I should go up anymore. It’s not safe for me, and it’s not safe for the group.’

Barely able to move, about an hour above Camp 2.

“The others didn’t go all the way to Camp 3, but continue on a bit more. Angela said she got a headache really bad and couldn’t see out of her right eye. I had already pretty much decided — I was devastated — after two nights and two days of not acclimating. Alejo had a stethoscope and said my left lung was crackling. We thought I might develop some really serious pulmonary edema.”

Keshari Thakali, PhD is an Assistant Professor in the Department of Pediatrics at the University of Arkansas for Medical Sciences in Little Rock, AR. She is a cardiovascular pharmacologist by training and her research laboratory studies how maternal obesity during pregnancy programs cardiovascular disease in offspring. When not at work, you can find her mountain biking, rock climbing, hiking or paddling somewhere in The Natural State. She has a long-term career goal of merging her interests in mountaineering with studying cardiovascular adaptations at high altitude. She has climbed to some of the most extreme elevations in the Rocky Mountains, Andes and Himalayas. Last December, she flew down to Mendoza in Argentina for an ascent up Aconcagua.

Sacred in ancient and contemporary Incan culture, and the highest peak in the Americas, Aconcagua summits at 22,837′ (6960 m). Current statistics show only 30 – 40% of attempted climbs reach the top of this massive mountain in the Andes, in Principal Cordillera in the Mendoza Province of Argentina.

Sunset on Aconcagua from Base Camp.

The day following Keshari’s decision not to summit, she hiked back down to Plaza de Mulas (14,337’/4370 m) from Camp 2, carrying some of her colleague’s gear that he didn’t want to take up to the summit as he continued to ascend. Plaza de Mulas is a large base camp area with plenty of room for tents, available water, and large rocks that provide some protection from the wind as climbers take time to acclimate before continuing their ascent.

“Even though my oxygen [saturation] was low, I was functional. As you go down, everything gets better. The others continued up to Camp 3. They spent one night there, then summited the next day. It took them 12 hours.

“The day the others came back to Plaza de Mulas, I think that’s when everything hit me. I felt like a zombie. I did some bouldering and got so tired I had to sit down and catch my breath often, probably because I had been hypoxic and we were at over 14,000′.

“[The next day] we did the really long hike from Plaza de Mulas all the way to the entrance of the park. It probably took about 8 hours to walk all the way to the park entrance.

“We drove to Mendoza that night. I felt like my body was tired, but my muscles were functioning just fine. It’s hard to describe.”

They had done everything right and had taken every precaution. Each of Keshari’s colleagues boasted significant backgrounds in climbing and mountaineering, their cumulative accomplishments including Mt. Elbrus (18,510’/5642 m), Cotopaxi (19,347’/5897 m) and Denali (20,335’/6198 m), their ages 30 to 65. They weren’t initially planning to hire porters, “but they ended up carrying a lot of our stuff. In the end, it just makes sense to hire these porters to increase your chance of success.”

They gave themselves about two weeks to make the ascent and return. There was ample time for them to stop at each camp and spend time acclimatizing, including day hikes to the nearby peaks of Bonete and Mirador.

“Day 4 [we did an] acclimatization hike to Bonete (16,647’/5074 m), pretty much the same elevation of Camp 1. You look at the mountain and it looks pretty close, but … in mountaineering, you don’t do distances, you do time. Did the hike in mountaineering boots, which were heavy and clunky, but I learned how my boots actually work. You walk differently in these than a shoe with a flexible sole. The last part of the mountain is pretty rocky and it looks like you’re almost to the top, but you still have to walk an hour to the summit. It took about five hours to go up. We were walking slow, I felt fine. From the top of that mountain, looking away from Aconcagua, you can really see Chile and the Chilean Andes.”

Summit of Bonete.

All the way through their first week of climbing, including a day of resting and eating after their hike up Bonete, Keshari was feeling fine.

“Day 8, we made the push to Camp 2 (18,200’/5547 m). None of these hikes made me tired. I was plenty trained. We were carrying packs, but they were still pretty light, packed with stuff for the day. We spent the night at Camp 2, took oxygen mostly at night. [My] first reading at Camp 2 was low. We were at over 18,000′. I thought maybe I’ll just go to sleep and it’ll get better.

Looking down on Camp 2 covered in snow.

“Day 9 was a rest day at Camp 2 because the weather was really bad. All I did was sleep that day. If you’re gonna go to Camp 3, that means you’re gonna do a summit push the next day, because Camp 3 is so high. You’re just struggling to stay healthy. I felt really bad in the tent, but if I went outside to pee or walk around, I felt better. My pulse ox was still pretty low that day. That night, a snow storm blew in and it snowed a lot.” And it was the following day of their ascent to Camp 3 that Keshari made the decision not to summit.

Since returning from her expedition, she’s reflected on some other variables. “I swear I was hyponatremic (an abnormally low concentration of sodium in the blood). We went through four liters of water a day with no salt in the food. I was having these crazy cramps in my abs and my lats and places I don’t typically get them. To me, that has to do with electrolyte imbalance. Next time, I’m taking electrolyte tablets, not just stuff to mix in my water.

“I’m not very structured in my diet. In general I eat pretty clean, but I don’t count calories. I eat vegetables, but I also hate going grocery shopping. I feel like I eat a pretty balanced diet. If I buy meat, I’ll buy a pack of chicken and that’s my meat for a week or two.

“On the mountain, in general, I felt like they fed us way more fiber. In Argentina, they eat a lot of meat. They’re meat-eaters. They didn’t feed us steak on the mountain, but … at Base Camp, I felt like they were overfeeding us. We had pork chops one night, but on the mountain, I felt like it was mainly lentils and noodles. Even though you’re burning calories, how your body absorbs them is different. They really try to limit your salt intake because they’re concerned about having too high blood pressure. At Base Camp, breakfast was always scrambled eggs with bacon and toast. Lunch and dinner were always three course meals starting with a veggie broth soup. They fed us like kings … I brought Clif blocks with caffeine in them for hiking snacks, Lara bars.”

I ask about her main takeaway from it all:

“I think I need more time to acclimate. I don’t know how much more time, but maybe more time at about 16,000′. Maybe take Diamox. Someone suggested I should have been on an inhaled steroid, especially because my asthma is worse in the cold. If I were to go next time, I would want a couple more days at 15,000 – 16,000′. Maybe the Diamox is something I would need to use next time.

“The nerd in me wants to measure pulmonary wedge pressures (via very invasive catheters; you could go through the jugular), nothing practical,” she laughs. “The pulse oximeter is the easiest tool.”

One last thing she’d do differently? One of her colleagues bought a hypoxic generating system from Hypoxico, “which I think puts CO2 back into your system; sleeping high, training low. That might have been the best thing.”

Keshari went sky-diving back in Mendoza the day after returning from their descent. “I was expecting a lot of adrenaline jumping out of an airplane, but there was none. I enjoyed the freefall, but when the parachute went up, I got really nauseous. Maybe I had just been stressed for so long, there was no more adrenaline left. I was like, ‘Where’s the risk involved in this?'”

An illustrated oxy-journey.

Keshari also summited Cotopaxi earlier the same year. Read her own account here.

robert-ebert-santos

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.

Oxygen

It has everything to do with how well the body functions at increasing elevation. In Summit County, Colorado, we live at an average elevation of 9000′ (2743 m). Most bodies start a significant physiological response to 8000′ (2438 m). Even healthy athletes experience shortness of breath during certain activities that wouldn’t be noticeable at lower elevations. The body compensates by circulating more oxygen-carrying red blood cells, because there isn’t as much oxygen packed into each breath you take. Heart rate increases, you take quicker breaths, speeding up your ventilation. You are hyperventilating. If you manage well enough for a couple weeks, your body will eventually start creating more red blood cells to circulate more oxygen throughout your body at all times. This process will peak at about three months.

We often get questions about the canisters of oxygen sold at convenience stores, souvenir shops and gas stations across Colorado and whether or not they make any difference. There is a 100% consensus among every physician, athlete, EMT and ski patroller we have ever interviewed that they do not.

Why not? Dr. Chris has been practicing medicine at 9000′ for 20 years in Frisco, CO, so I asked her a couple of the questions that have come up at our clinic and on our blog recently and frequently.

How much oxygen is needed to actually mitigate symptoms of altitude sickness?

For someone with low blood oxygen saturation, our target would be 90% . They should be put on a concentrator or a large tank [of oxygen]. The adult dose is 2 to 4 liters per minute, the pediatric dose can be between 1/4 L per minute and 1 L per minute, 24 hours a day, for up to a week, or until their oxygen saturation can maintain at 90%. Less than that, and usually, it will drop again after 10 minutes off oxygen; and it’ll often be lower when you sleep, too.

What if I bought ten of these canisters of oxygen available at the gas station and breathed all of them in, one after the other. Would that make a difference?

You might get three hours worth of oxygen if you bought ten of those store-bought cans, which might help an altitude sickness-induced headache. But again, your oxygen would likely drop shortly thereafter, and you would be experiencing the same symptoms.

What happens if someone struggling with acclimatization also contracts COVID-19 or another disease with associated respiratory complications?

We don’t know. Their oxygen requirement might be higher. All of us at altitude might be at greater risk than someone living at sea level.

When do you make the decision to send someone to a lower elevation? How low?

If they are having trouble breathing in spite of being on 4 L of oxygen per minute. If they need more than that, we would send them to a lower elevation. Most people are fine going to Denver. By Georgetown (8530’/2600 m, a town between Summit County and Denver), they’ll experience an improvement. It’s above 2500 m where altitude issues become problematic.

Research in recent years, including our own, is revealing many other different variables that may affect an individual’s ability to acclimatize to high elevations, including different hormones, genetics, and muscle mass. We continue to advise anyone traveling to the Colorado mountain region above 7000′ from lower elevations to stay hydrated and well-rested, and time a slow ascent, planning to spend at least 24 hours in Denver, or another comparable lower elevation, before arriving at your final destination.

robert-ebert-santos

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.