How life at altitude impacts people — and animals
STEAMBOAT SPRINGS — People living at higher altitudes tend to be healthier, but definitive evidence as to why remains elusive.
There is debatable data, and some contradictory studies, as well as the persistent prospect that, especially in a place like Colorado, a lot of it has to do with selection: healthier people with healthier habits choose to live at higher locations.
There’s also somewhat of a “survival of the fittest” aspect, noted Dr. Will Baker, a cardiologist with UCHealth Heart and Vascular Clinics in Steamboat Springs and Craig.
Some thrive in a more challenging climate and geography with less oxygen, and some don’t.
It also very much depends on the individual, of course.
People with underlying health issues, especially related to the lungs and heart, may find their conditions exacerbated by the altitude.
In general, said Baker, people with chronic lung problems, especially Chronic Obstructive Pulmonary Disease (COPD), will have a harder time living at altitude. The same goes for some heart conditions.
However, there is also research showing altitude having potential protective effects on the heart.
In a 2014 National Center for Biotechnology Information study titled “Effects of Living at Higher Altitudes on Mortality,” author Martin Burtscher wrote, “The available data indicate that residency at higher altitudes are associated with lower mortality from cardiovascular diseases, stroke and certain types of cancer. In contrast, mortality from COPD and, probably also, from lower respiratory tract infections is rather elevated. It may be argued that moderate altitudes are more protective than high or even very high altitudes. Whereas living at higher elevations may frequently protect from development of diseases, it could adversely affect mortality when diseases progress.”
In studies spanning the globe, researchers have seen several consistencies in people living at higher elevations: they weigh less, have less cardiovascular disease and some types of cancer and live longer.
But it isn’t so straightforward to say that if you come to — or are born at — a higher altitude, you will lose weight, be healthier and live longer, noted Baker.
It’s a lot more complex and so is the available research.
For example, while increased exposure to ultraviolet rays may increase the risk of skin cancer, the increased levels of Vitamin D intake may also have protective effects that “profoundly influence cardiovascular mortality,” according to Burtscher.
Some studies show people with asthma do better at higher altitudes. Some show they do worse.
And in terms of what Burtscher described as moderate versus high or very high, 6,000 to 7,000 feet can treat a body differently than 9,000 to 10,000 feet.
“High altitude to a physiologist starts around 5,000 feet, altitude where the body senses changes in the oxygen level and starts to respond by increasing breathing,” according to the Institute for Altitude Medicine in Telluride.
There is a reason the U.S. Olympic & Paralympic Training Center is located in Colorado Springs, noted Dr. Brent Peters, a pulmonologist at UCHealth Pulmonology Clinics in Steamboat Springs and Loveland.
It’s 6,035-foot elevation is a “sweet spot” that provides the most conditioning benefit in terms of ideal oxygen deprivation.
The relationship between lower body weights and altitude comes with several hypothesis.
A 2013 study in the International Journal of Obesity found a strong association between altitude and obesity in the United States. Using data from more than 400,000 people, researchers found people living closest to sea level were four to five times more likely to be obese, compared to people living significantly above sea level in Colorado.
One possibility is simply that people exercise more — though the study did control for that factor and still saw people losing weight.
One theory has to do with eating fewer calories — altitude has been shown to increase levels of leptin, a protein hormone that plays a role in appetite control and metabolism. Hypoxia (lack of oxygen) also is known to cause a loss of appetite.
In terms of how a body living at altitude varies from one living at sea level, the primary thing that happens in terms of physiology, said Baker, is that the blood compensates with a higher amount of hemoglobin, which increases the amount of oxygen that can be carried.
One thing Baker does see on a regular basis is more severe impacts from sleep apnea.
Sleep apnea is defined by the Mayo Clinic as “a potentially serious sleep disorder in which breathing repeatedly stops and starts.”
Peters, who travels around the state providing care, said he also sees an “acceleration” or “exaggeration” of sleep apnea in patients.
“They basically don’t breathe well at night,” Baker said. They wake up frequently and feel fatigued the next day. Often those people sleep better and feel more energetic at sea level.
There’s also a wide spectrum of sleep apnea and different kinds, Peters noted. Most sleep apnea cases are classified as obstructive, in which a person can’t breathe normally because of an upper airway obstruction, occurring when throat muscles relax.
Central sleep apnea, which is less common, “occurs when your brain doesn’t send proper signals to the muscles that control breathing,” according to the Mayo Clinic.
Peters said he sees more central sleep apnea in Colorado than other places.
According to a Medlink Neurology report, “Central sleep apnea due to high-altitude periodic breathing affects about a quarter of people who ascend to 2,500 meters (8,202 feet) and almost 100% of those who ascend to 4,000 meters (13,123 feet) or higher.”
Kids can also experience difficulty sleeping at higher altitudes, said Dr. Steven Ross of Sleeping Bear Pediatrics.
Before they can verbalize how they feel, very young children may seem restless at night and irritable during the day, he said, especially above 7,500 feet.
If a normally energetic kid sits down and whines on the Uranium Mine Trail while hiking or at the top of a ski run, there’s a good chance they are experiencing effects of altitude, Ross said, and aren’t just spoiled and lazy.
And that goes for kids who live here as well as visitors, he said.
When recreating at higher altitudes, Ross advises parents to make sure kids are hydrated and well protected from the sun. Make sure they get good sleep, and “factor in patience,” he said. Be aware that kids may not have the same endurance they do at lower elevations.
High altitude effects on babies
Altitude does play a significant role as babies develop in utero, described Allyson Daugherty, a neonatal nurse practitioner with Childrens’ Hospital Colorado who cares for newborns in the special care nursery at UCHealth Birth Center in Steamboat Springs.
Babies born at higher altitudes (especially over 8,000 feet) are typically smaller in size.
“Altitude contributes to overall growth from a weight perspective,” she said.
And, for those tiny developing lungs, mothers making it to the 36-week mark is imperative, she said.
Lungs continue to develop until two to five years of age, Daugherty said, but those last few weeks in utero is crucial, and the primary reason doctors want to see mothers, particularly at higher altitudes, make it to term (40 weeks). “The more premature a baby is, the more susceptible the baby is to respiratory distress.”
Babies can become hypoxic, she said, and frequently need a little more oxygen during those first few months of life as their lungs mature — especially if they are born prematurely.
A lot of babies born at UCHealth Yampa Valley Medical Center are given supplemental oxygen, Daugherty said, as are babies who are born in Denver and travel to Steamboat or are going home to elevations higher than Steamboat.
Even babies who make it to 36 weeks may need some support to continue their lung development after they are born. But those lungs can, and usually do, mature fully after birth without any lasting detrimental effects.
“A huge portion of babies (born at YVMC) go home with oxygen whether they are pre-term or term,” she said.
The American Academy of Pediatrics recommends parents sleep in the same room as their babies at least up to 6 months of age, Ross said, something even more important at high altitude. The optimal recommendation is sleeping in the same room through 12 months of age.
The good news is, said both Peters and Baker, most people — young and old — adapt quite well and relatively quickly.
Peters noted that many of his patients are “snowbirds,” and he asks them to take note of any differences in how they feel living at the different elevations.
Both doctors say it is rare they will tell a patient they should move to a lower elevation.
Only in the most extreme cases, Baker said, will he tell a patient they should move — when, even with supplemental oxygen and other medical interventions, in the face of significant lung or heart disease, “We just can’t keep them in a safe zone.”
Of course, many people who do live at altitude, especially as they age, use supplemental oxygen.
Supplemental oxygen, as well as medication, can help people with pulmonary hypertension (high blood pressure of blood vessels in the lungs), which can worsen at higher elevations.
Aside from those rare cases, some people make their own decision if they find they feel more energetic and are able to be more active at sea level, Peters said.
There’s also the eternal importance of maintaining a general level of fitness. Baker thinks this may have more to do with people living longer at high altitudes than anything else.
“It’s not cut and dry,” emphasized Peters. For people, especially as they get older, altitude may stress the lungs, but the low humidity and clean air can also make it easier to breathe. Some people may feel better higher up, some worse.
What about my dog?
For the average healthy dog or cat, without any underlying diseases, altitude doesn’t have any significant negative impact on your pet’s health, said Rocky Mountain Veterinary Ultrasound Dr. Kim Radway.
But when an animal has heart disease, which happens with aging, altitude can increase the severity of the impacts of the disease.
Radway also said she sees a significant increase in the amount and severity of pulmonary hypertension in high altitude dogs and cats — which means high blood pressure in arteries leading in and out of the lungs.
If the high blood pressure becomes too severe, it can cause disease and failure of the right side of the heart.
Radway sees more cases than the average vet because she travels around the region giving cardiac ultrasounds — the only way to diagnose pulmonary hypertension. It is much more common in dogs than cats.
In addition to the dogs living at high altitude, Radway said she often sees pulmonary hypertension present itself suddenly in dogs traveling relatively quickly from sea level to higher altitudes.
To treat the condition, Radway prescribes the pet equivalent of Viagra. No, she said, your male (unnuetered) dog is unlikely to experience the same side effects as a human male because of dosage.
But, like in humans, the drug increases blood flow to particular parts of the body — including the lungs. It doesn’t provide a complete reversal, she said, but works pretty well. There are also several other medications that can help, as well as oxygen and restricting exercise.
Signs your dog might have pulmonary hypertension include rapid breathing, coughing, signs of lethargy, and syncope, which is a loss of consciousness due to lack of normal blood flow to the brain.
Another altitude side effect Radway sees is an increased negative impact on pets from smoke — whether that be cigarettes, cigars or marijuana.
For helping your furry friend guard against negative impacts of altitude, Radway recommends decreasing the animal’s exposure to airway irritants, and if traveling back and forth to low altitudes, giving your dog time to adjust.
While heart disease is hard to prevent, she recommends preventing heartworm — particularly when traveling to places where it can be 70 degrees or warmer for a full 24 hours. And there are medications that can alleviate some of the effects of heart disease.
Like humans, dogs can get altitude sickness, though it is much less common. Symptoms include vomiting, excessive drooling, panting, ear discomfort and lethargy. In extreme cases, it can cause a build up of fluid in the lungs and brain.
Prevention tips include making sure your dog is hydrated, giving them time to acclimate and taking it easy.
This is part two of a four-part Longevity Project from the Steamboat Pilot & Today. The series also includes profiles on Routt County locals who are thriving at altitude.
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