Category Archives: High Altitude

How Long With Low Oxygen?

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.


Aging and altitude illustrated

Ever since I moved to the mountains I have been impressed by the number of older adults that pass me up on the trails hiking or mountain biking.

“Altitude is a fitness challenge in itself”, wrote Eric Swenson in the Journal of High Altitude Medicine and Biology May 2015. “Low fitness contributes to events” [altitude illness]

People who live in the mountains usually stay very active, like this hiking group from St. John the Baptist Episcopal church that goes out every week.



Two of these senior citizens hiking at 12,500 feet sleep on oxygen. They are residents living above 9,000 feet.
Two of these senior citizens hiking at 12,500 feet sleep on oxygen. They are residents living above 9,000 feet.




Aging is protective against Mountain Sickness at moderate altitude

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

Pulmonary hypertension may be common in high altitude residents

Summit County cardiologist Warren Johnson is impressed by the numbers of people with elevated pressures in their lungs. “It could be as high as 30 per cent of adults,” he told local physicians gathered at a presentation this week. Symptoms are subtle: decreased exercise tolerance, mild shortness of breath, trouble sleeping, high red blood cell counts. Most people just think they are out of condition or aging.

A study in SpitiValley India of residents living at 9000-13000 ft found an incidence of three per cent with PH.  Dr Johnson suspects this is a highly adapted population with centuries of mountain living.

Diagnosing this condition early with Echocardiogram can prevent serious disability.  Treatment is as simple as sleeping on oxygen

SIDS incidence double above 8000 ft

Dr. David Katz at the University of Colorado reviewed 393000 births between 2007-2012. Of these 80% live between 3000-6000 ft. Only 1.9% live over 8000 ft. Death rates from Sudden Infant Death Syndrome state-wide was 4.2 per 10,000 but over 8000 ft the rate was 7.9/10000.

it is possible that hypoxia is a contributing factor, but there is no research on this. Meanwhile parents are urged to place their babies on their backs to sleep and remove all soft material from the sleep area.

Does sleeping on oxygen at high altitude improve athletic performance?

I have read many scientific studies on athletic performance at altitude. Active high altitude residents are always looking for ways to improve. As we age we experience a loss of speed and endurance, even with regular training. Some of this is inevitable, but how can we know if there is something else affecting our fitness?

I started sleeping on oxygen 9 months ago because of high blood pressure, which was instantly cured. Now I find that my strength and endurance have improved during the last few months. For example, I was rowing 13400 meters per hour with several brief pauses last fall, and now I am at an all-time high of 14100 m per hour with one pause. My running feels better, I’m back up to 6 miles from 4.

There are other factors that could influence this. In 2012-2013 I was on 17 pills including prednisone and had four surgeries for tongue cancer and myasthenia gravis. I was able to continue working out daily although part of that was less intense, such as yoga. I also had rotator cuff surgery. So my current fitness improvement could just be a rebound from overcoming those health conditions.

The only way to know for sure is to do a randomized controlled double blind study of athletes performance on and off nightly oxygen, or study the same athlete with and without oxygen. This is not an immediate effect, so months or years of observation and measurements would be needed.

In the meantime, if you live above 2500 meters/9000 feet and are losing stamina or strength consider having a night time pulse oximetry test to check for hypoxia during sleep.

School problems and orthodontics

My nurse practitioner Laura Amedro and I met with local orthodontist Al Bishop yesterday. Sleep problems are more common at high altitude, and providers caring for children know that poor sleep can cause difficulties with learning and behavior, including ADHD. Dr. Bishop listed ten diseases made worse by poor sleep, including obesity, diabetes, high blood pressure, depression and others. 

How does this tie in with the person who provides braces? Dr. Bishop showed us photos of mouths and teeth that can cause airway constriction.  Expanders inserted inside the mouth (no more “head gear”) correct these problems but are more effective when started earlier. Some children can be identified and treated as early as 7 years.

Dr. Bishop has offices in Edwards and Summit County, so he is familiar with altitude issues. Night time oximetry is the recommended screening test for airway problems. This has to be ordered by a health care provider such as Laura or myself.

Sleeping at altitude

Most people will agree they do not sleep as well at high altitude, especially over 9000 ft/2500 m. In sleep, the drive to breathe is blunted, which may lower the oxygen and raise carbon dioxide in the blood. This  causes high blood pressure in some adults and children but what else does it cause? Pediatric pulmonologist and sleep specialist Ann Halbower wonders if it effects growth and development in children. Family practice physician Lisa Zwerdlinger has many years of experience treating patients in Leadville and sometimes has babies that need oxygen for a year to gain weight.

A study published in the Archives of Diseases of Children in February this year analyzed previously published studies of oxygen levels in awake children at altitudes between sea level and 4000 meters, including Summit County.  We are in the early phase of formulating a study on night time oxygen levels at various ages. since it takes years for research to be completed we recommend anyone with health issues that may be related to altitude to have a sleep study. this is very simple: a finger clip connected to a wrist band where data is collected.


Overflow crowd tonight at St. John’s church where Katherine Jeter shared her story of climbing Mt Kilimanjaro with others from the county, celebrating her 75th birthday that year. I am so inspired by the people older than I am who are challenging themselves like this. This peak is a mile higher than our 14er’s! The average age in this group was 65. Using acetazolamide/Diamox helped many of the climbers.

When Should Oxygen Be Given To Children At High Altitude?

This article was published in the Archives of Disease in Childhood in 2009.

The authors reviewed 14 studies in the scientific literature for normal oxygen values for children ages 1 week to 12 years.

Hypoxemia (low oxygen) was defined as oxygen saturation at or below the 2.5th% for healthy children at a given altitude.

At 8,200 feet (2,500 meters) elevation 97.5 % of children had oxygen concentrations above 90%

At 10,498 feet (3,200 meters) elevation this decreased to 85%, with  2.5 % of children were below this.

Should children living in Leadville, Alma and Fairplay be allowed to go untreated when their oxygen levels are 85-89%?

Now that many families have a pulse oximeter parents are measuring their children’s oxygen levels when they are sick, and presumably when they are well.

Therefore deciding when a child has a low oxygen that needs treatment can be based on the child’s levels when healthy. Unfortunately, these oximeters are not accurate in infants.