Category Archives: Acclimation

What happens to your body’s physiology when you move between low and high elevations?

Acclimation, Child Growth & Development, Health, High Altitude, High Altitude Training & Fitness, Medicine, Mountaineering

Slumber Up: Sleeping at High Altitude

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Does high altitude affect sleep quality? The answer is that for some, it does. If you’ve ever quickly arrived to the mountains on a ski or summer getaway, you may have experienced fitful and non-restful sleep. Individual responses to high altitude may vary, however there is an understood physiological basis for sleep disruption at altitude.

 

A phenomenon known as “periodic breathing of altitude” is commonly experienced above 2500 m of elevation (about 8200 ft) in those not previously acclimatized [2]. This is a common sleep elevation in Colorado mountain towns such as Frisco, Colorado (proud home to this blog!). Periodic breathing of altitude may be more likely to occur as sleeping altitude increases. Here’s the science behind it:

 

The decreased atmospheric pressure at altitude results in less oxygen driven into the lungs and through to the bloodstream. The body attempts to compensate by increasing the rate of breathing (tachypnea), which also causes more carbon dioxide to be exhaled. Chemoreceptors sense the decrease in carbon dioxide and signal the body to stop breathing temporarily (apnea) to correct the imbalance. Alternating cycles of tachypnea and apnea continue to occur during sleep. The result is decreased REM sleep, which is a critical restful and rejuvenating phase [2].

 

Worried about your next sleepless night on a mountain trip? Fortunately, there’s acetazolamide (Diamox). It is a carbonic anhydrase inhibitor that works by eliminating bicarbonate in the urine, which is a base. The body subsequently becomes more acidic, and that acid in the bloodstream is readily converted to carbon dioxide. The body is “tricked” into thinking that there is plenty of carbon dioxide present in the bloodstream, and periods of apnea during sleep may be reduced or eliminated [3].

 

To help prevent periodic breathing of altitude, adults can take acetazolamide preferably starting on the day before ascent or on the first day at altitude. Adults typically take 125 mg twice a day until either 3 days at altitude has been reached or descent back down has occurred [1]. Ask your healthcare provider about what’s right for you. Consider acetazolamide next time you’re sleeping up high, and get that refreshing sleep that allows you to better enjoy the things you love at altitude!

 

-Justin Murphy, PA-S

Red Rocks Community College Physician Assistant Program

Clinical Rotation- May 2017

 

References

1) Athena Health (2017). Acetazolamide generic. Epocrates Online. Retrieved from: https://online.epocrates.com/drugs/12701/acetazolamide/Adult-Dosing

2) Gallagher, S. A., Hackett, P., & Rosen, J. M. (2017). High altitude illness: Physiology, risk factors and general prevention. Up To Date, Topic 181,  Version 20.0.  Retrieved from: https://www.uptodate.com/contents/high-altitude-illness-physiology-risk-factors-and-general-prevention?source=search_result&search=high%20altitude%20sleep&selectedTitle=2~150

3) Winter, C. (2016). Sleeping around: How to sleep at high altitude. Huffington Post. Retrieved from: http://www.huffingtonpost.com/entry/sleeping-around-how-to-sleep-at-high-altitude_us_5806da29e4b08ddf9ece1228?ncid=engmodushpmg00000006

Acclimation, Health, High Altitude, Medicine

Heart Attack Deaths at Elevation in Visitors

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Last year in Summit County, 23 people died of heart complications, 19 of which were visitors ascending to higher altitude.  Most of these visitors were in their 50s or older and died within one to two days after coming to elevation (Queen, 2017).

Acute exposure to high altitude over 2500 m can cause great strain on the body and is associated with significant alterations to the cardiovascular system such as tissue hypoxia and increased pulmonary artery pressures.  Although the concentration of oxygen at elevation is the same at sea level, the air is thinner causing less oxygen to breath.  At sea level the percent of effective oxygen concentration is around 20% where as in Summit County the percentage of effective oxygen drops down to 14%.  At higher elevation such as the ski areas the percentage of effective oxygen drops down to 13% (Queen, 2017).  As a result, the heart will pump faster to increase the delivery of oxygen to the body.  The cardiac stress at rest is minimal, however it can be significant during exercise.  Anyone with some degree of heart complication can worsen the stress on their heart when coming to higher elevation (Bach, 2013).

Hypoxemia due to high altitude can cause poor oxygenation of the lungs and constriction of blood vessels, causing an increase in pulmonary pressure and increasing hypertension.  Therefore, an acute exposure to high altitude can cause cardiovascular stress.  Residents of high elevation tend to do better because they have anatomical and physiological changes in their cardiovascular system that allows them to adapt to high-altitude chronic hypoxia (Hurtado et al., 2012).

It is recommended that any patients with cardiovascular disease who are from sea level and planning to come to elevation should slowly acclimatized themselves by staying in Denver for a day or two prior to going above 2500 m.  Patients who have stable heart complications should limit their physical activity for the first few days after ascending to elevation.

Hong Nguyen, PA-S

Physician Assistant Student

Red Rocks Community College

References:

Reference:

Bach, D. (n.d.). Altitude and the Heart: Is Going High Safe for Your Cardiac Patient? Retrieved March 28, 2017, from http://www.expeditionmedicine.co.uk/index.php/advice/resource/r-0034.html

Hurtado, A., Escudero, E., Pando, J., Sharma, S., & Johnson, R. J. (2012). Cardiovascular and renal effects of chronic exposure to high altitude. Nephrology Dialysis Transplantation, 27(Suppl 4), Iv11-Iv16. doi:10.1093/ndt/gfs427

J. Q. (n.d.). High elevation may be linked to visitor heart attach deaths. Summit Daily, pp. 1-4.

Acclimation, Health, High Altitude, Medicine

drugs and altitude:

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Consensus by International Federation on Drug Use at High Altitude

New Rochelle, NY, October 25, 2016—Drug taking at high altitude is variably intended to enhance performance, prevent or alleviate the debilitating effects of altitude, or for pleasurable use. In some cases, certain drugs can be advantageous and even life-saving, but many drugs lack evidence of benefit and carry risks of side effects or interactions. The International Climbing and Mountaineering Federation (UIAA) has published evidence-based guidelines advising on the safe use of alcohol, steroids, oxygen, erythropoietin, and many other types of drugs in mountain environments in an article in High Altitude Medicine & Biology, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The article is available free online on the High Altitude Medicine & Biology website.

An international team of researchers from Kuwait, Austria, United Kingdom, Germany, Switzerland, Nepal, Spain, France, and the Netherlands, led by David Hillebrandt, MB, BS, President, UIAA Medical Commission, coauthored the article entitled “Drug Use and Misuse in the Mountains: An UIAA MedCom-Consensus Guide for Medical Professionals.” They conducted an extensive review of the medical literature, trials, observational studies, and case series to assess the evidence available for drugs commonly used by mountain climbers. Their conclusions and recommendations cover a broad range of drug types including alcohol, anabolic agents such as androgenic steroids, adrenergic agonists, beta-blocking agents, erythropoietin, oxygen, glucocorticosteroids, benzodiazepines, and stimulants such as amphetamines.

“The use of drugs beyond those proven effective in preventing and treating high altitude illnesses remains very controversial among both physicians and climbers,” says Erik R. Swenson, MD, Editor-in-Chief of High Altitude Medicine & Biology and Professor, Division of Pulmonary and Critical Care Medicine, Veterans Administration Puget Sound Healthcare System. “This broad and comprehensive review of the myriad drugs used for various purposes in climbing will be useful to all concerned in decision-making about their use, determining the level of supportive evidence, and importantly their potential costs and adverse effects.”

Acclimation, Child Growth & Development, Health, High Altitude, Medicine

High-Altitude Lung Edema Can Mimic Pneumonia in Kids, Even Without Travel by Rob Goodier

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Dr. Chris has the medical community talking about HAPE!!!

“Health providers should advise patients who live at or travel to high altitude to have a pulse oximeter and check their oxygen levels if they are unwell,” the study’s author, Dr. Christine Ebert-Santos at the Ebert Family Clinic in Frisco, Colorado, told Reuters Health…

Click the link to read more:

High-Altitude Lung Edema Can Mimic Pneumonia in Kids, Even Without Travel by Rob Goodier

http://www.medscape.com/viewarticle/867210

Acclimation, Child Growth & Development, Health, High Altitude, Medicine

Those precious epi-pens at altitude

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With all the news about the 400% price increase in epi-pens, we don’t want to waste them. So what if we are backpacking at high altitude and eat some peanut butter by mistake in our energy bar? Then our face swells up like a chipmunk and we start to wheeze? We whip out the epi-pen from the external pocket of our pack only to find out it is frozen!!  Oh, oh. What do we do now? Good news! at the 7th World Congress of Mountain and Wilderness Medicine in Telluride we heard the exact scenario described. It happened to a scientist, who then did a study to measure the effectiveness of the epi-pen after freezing and thawing. It still worked! So don’t throw out your frozen epinephrine. thaw and use.

Another tip: if you can’t afford the new price of the epi-pen, maybe your physician could prescribe injectable epi with a syringe to have on hand.

Acclimation, Child Growth & Development, Health, High Altitude, Medicine

Reflection to MRHAPE in the Mountains: Resident High Altitude Pulmonary Edema

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In beginning my Physician Assistant rotation at Ebert Family Clinic I was introduced to the exciting research of Christine Ebert-Santos, MD.  The research surrounded a condition known as High Altitude Pulmonary Edema (HAPE). In growing up at altitude myself, at 6,926 feet in Jamestown Colorado, I have had some exposure to the effects of high altitude. Acute Mountain Sickness (AMS) is a condition that I am more familiar with and in reading Dr. Ebert-Santos’ research it became clear to me that HAPE is a more severe complication to those ascending to or living at altitude, especially if they develop an initial respiratory illness. In her paper Dr. Ebert-Santos describes several pediatric case studies that demonstrate the characteristics of this treatable condition. These patients presented with tachycardia (fast heart rate), tachypnea (fast breathing), decreased oxygen saturation, and rales (abnormal breath sound).  Many of the children described were seen directly after an initiating illness such as the Flu. While seen in the clinic, or during admission to the hospital, these patients were treated with oxygen. The fact that HAPE can be treated with something as simple as oxygen is noteworthy.

Through her research Dr. Ebert-Santos has demonstrated that HAPE should be considered in all pediatric patients presenting to clinics  or emergency rooms at altitude with hypoxia (decreased oxygen saturation) and a recent viral illness. Through placing HAPE in their differential diagnosis, clinicians can avoid giving excessive inhaled steroid treatments and unneeded antibiotics. Awareness of the prevalence of this disease in both travelers and residents alike ensures a decrease in the incidence of unfavorable outcomes from this potentially fatal condition.

Submitted by Kelly Kyte, Physicians Assistant Student from Red Rocks Community College Fall Rotation 2016

Acclimation, Health, High Altitude

Rocky Mountain High?

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With apologies to John Denver, here in the mountains, it’s not just the sunshine on your shoulders that makes you smile. Scientists have been studying the effects of high altitude and mild hypoxemia on dopamine, one of the chemicals in the brain. Dopamine causes feelings of pleasure and happiness. At higher altitudes where oxygen levels in people are lower, dopamine levels are increased.

Here’s a little bit more on how that works: Oxygen makes up 21% of the atmosphere. At sea level, 100% of that oxygen is available to breathe. With a rise in altitude, barometric pressure decreases causing the air molecules to become more spread out. This means that at 10,000 feet above sea level, only 70% of atmospheric oxygen is available to breathe. This results in a state of mild hypoxemia, or lower levels of oxygen in the blood, which in turn causes increased levels of dopamine.

You can read more about dopamine and altitude here:

Toler, A. (2014). “Your brain on altitude.” Catalyst Magazine. Retrieved from http://www.catalystmagazine.net/your-brain-on-altitude-2/

Here’s more about the effects of altitude on oxygenation:

Peacock, A.J. (1998). Oxygen at high altitude. British Medical Journal, 317 (7165). p1063-1066.

Here a calculator to figure out oxygen and barometric pressure at different altitudes:

http://www.altitude.org/air_pressure.php

Submitted by Rebecca Somershoe PNP Student from Vanderbilt University rotating Summer 2016

Acclimation, Health, High Altitude, High Altitude Training & Fitness, Medicine, Mountaineering

Live High Train Low- What’s an athlete to do?

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I just came across this study in the literature from a couple years ago

Optimizing Altitude for Live High-Train

Low (LHTL) Training

Chapman et al (2013) hypothesized that athletes living at

higher altitudes would experience greater improvements in sea

level performance, secondary to greater hematological acclimatization,

compared to athletes living at lower altitudes. After

4 weeks of group sea level training and testing, 48 collegiate

distance runners (32 men, 16 women) were randomly assigned

to one of four living altitudes (1780m, 2085m, 2454m, or

2800 m). All athletes trained together daily at a common altitude

from 1250m to 3000m following a modified LHTL

model. Subjects completed hematological, metabolic and

performance measures at sea level before and after altitude

training. Upon return from altitude, 3000m time-trial performance

was only significantly improved in groups living at the

middle two altitudes. EPO remained elevated after 72 h except

in the 1780m group. Erythrocyte volume was significantly

higher in all groups but not different between groups. These

data suggest that a 4 week LHTL altitude camp at 2000m to

2500m is optimal for sea level performance.

 

HIGH ALTITUDE MEDICINE & BIOLOGY

Volume 15, Number 1, 2014

ª Mary Ann Liebert, Inc.

DOI: 10.1089/ham.2014.1513

4

 

Acclimation, Health, High Altitude, High Altitude Training & Fitness, Medicine, Mountaineering

How Long With Low Oxygen?

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We frequently measure oxygen levels on people of all ages here in our mountain clinics. We order nighttime oximetry and sleep studies and analyze hundreds of data points reflecting heart rate and oxygen levels over time. When we see someone with a low oxygen in clinic, there may be no way of knowing if they have been hypoxic for hours, days, weeks unless they have an illness with an abrupt onset, like influenza or pneumonia or they just returned from sea level. Babies during the first weeks may have low oxygen with no symptoms, since they are accustomed to this in the womb where oxygen saturations run 40-60 %.

A recent article in the Journal of the American Medical Association studied extremely premature babies at 18 months for adverse outcomes including vision, hearing, cognition, motor, and language. They correlated the degree of disability with the length of time the child was hypoxic during the first few months. One minute of hypoxia seemed to be the cut-off. Now this doesn’t tell us how low or how many but it may be a helpful guide when watching someone’s oxygen or analyzing a sleep study. Shorter episodes may be insignificant long term.

This is a complex article and the children with the poorer outcomes had more episodes of hypoxia at older ages- 9-10 weeks after birth. This could mean that the insult to the brain was contributing to the hypoxic episodes as well as the deficits.

 

Acclimation, Health, High Altitude

Aging is protective against Mountain Sickness at moderate altitude

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A study of 2789 men and 1886 women aged 14 to 85 years old showed a reduced risk of altitude sickness above age 46. The study controlled for age, sex, rate of ascent, final altitude, training status and chemoreceptor responsiveness. Thirty subjects were also evaluated again after a ten year interval.Aging men showed a decreased response to hypoxia with less pronounced desaturation. Men and women had a decreased cardiac response to low oxygen as they aged.

In this article there were numerous citations  of other studies including one that showed an increased risk of severe high altitude illness in endurance athletes.

Jean-Paul Richalet,1,2 and Franc¸ ois J. Lhuissier1,2 High Altitude Medicine and biology June 2015