Category Archives: High Altitude

A conversation with Dr. Chris on neonatal oxygen levels at elevations 9000’ and above

My name is Austin Ethridge, I am a physician assistant student from Red Rocks Community College PA program who has been fortunate enough to have completed my pediatric rotation with Dr. Chris in Frisco, Colorado, this month. Dr. Chris has extensive experience providing care to the pediatric residents of Summit County, having established her practice here in 2000, following 20 years as a pediatrician on Saipan, in the Northern Mariana Islands, southeast of Japan. She has a unique perspective on high altitude health, having transitioned from sea level to the 8000′ and above elevations unique to Summit County. Since moving here, she has been advocating for more in-depth medical research regarding the needs specific to these high-altitude communities. We are here in her office today at the Ebert Family Clinic to discuss neonatal oxygen use in Summit County.

Dr. Chris, based on your experience, why do neonates need oxygen at a higher elevation? Is it because they need to acclimate?

Yes, that’s basically it, and smaller lung size at birth.

Yes, that’s what I read. Basically, the maternal physiology compensates for the higher altitude. When the infant is born, their lung size and physiology need to catch up to the altitude.

Based on your practice, when do you place neonates on oxygen?

Usually at 89% or below, but you see, that’s just it. Many parents ask why their children need to be on oxygen when neither themselves nor their siblings were on oxygen. One of the primary reasons that this has become more of an issue is the less invasive methods of measuring oxygen saturation in the blood. Before the 1990s, the only time to measure oxygen saturation in a newborn was if a concern for illness or pulmonary problems existed, which was completed by obtaining an arterial blood gas, a very invasive procedure. Do you know at what oxygen saturation level we begin to detect cyanosis in neonates?

Around75%, which means before the pulse oximeter used today, we had no idea if the infant’s oxygen saturation was in the 80s! Now that we have the pulse oximeter, we have access to so much more information. And this is why it is essential to determine the normal oxygen levels for these infants at higher elevations.

Does this include cyanosis or blue discoloration of the hands and feet, or is it just central as in the face and chest?

The blue discoloration of legs and arms do not count; this is very common and not concerning, only the discoloration of the trunk and face.

Yes, based on the articles that I have been reading while I have been here, there are not many studies that reflect normal oxygen saturation in neonates at a higher elevation. Most of the articles that I did find determined that newborn oxygen saturation is lower at elevations of around 6000’, with average values within the range of 89-96% SpO2 compared to greater than 97% at sea level. However, there could be a significant difference between 9000’-10000’ feet and the 6000’ in these studies.1-3

That is exactly right, and that is why I want to do a study here in Summit County to determine the average oxygen saturation at these altitudes.

On average, how many newborns do you place on oxygen in Summit County?

About 40% of newborns are placed on oxygen due to low oxygen levels at birth, and I would say that less than 5% will still need oxygen after their two-week visit; however, this rate may be higher in those that live at elevations of 10,000′ or greater. In general, studies have observed that the lowest oxygen levels tend to occur around the 4th day of life and then improve from this point onward. What is the main complication that we are worried about in infants that have low oxygen levels?

Pulmonary hypertension. At birth, when the fetal circulation is shunted back through the lungs, the pulmonary pressure decreases to allow this to happen. If the oxygen levels are too low, the vessels in the lungs may not dilate enough, and this could lead to elevated pulmonary pressures. I read an interesting study that found increased pulmonary pressures in Tibet children as measured by ECHO cardiogram until the age of 14. These pressures were noted to increase with increasing elevation but to decrease with increasing age. Generally, by the age of 14, the pulmonary pressures had normalized; the authors considered this to be a normal physiological response. However, it is worth noting that these children in the study came from generations of individuals that have always lived at these altitudes.4-5

That is correct. That is the difference between adaptation and acclimatization. Many of the children that live up here are acclimatized, meaning that their bodies have adapted on a physiological level, but their genetics remain the same. However, adaptation is observed in many families that have lived at high elevations for generations; in these instances, the changes have occurred at the genetic level.

That makes sense; so the data from some of those studies may not directly apply to the population here.

That is correct. Are we worried about brain damage in this setting of low blood oxygen levels?

No, I do not think so.

We are not! In fact, as an example of this: when I was in Saipan, there was a child that had a cyanotic, congenital heart defect that was unable to be repaired for social reasons. This child always appeared blue, and his oxygen saturation would have been very low. He did just fine in terms of development and progress in academics. There were no signs of developmental delay or any other neurological problems at all.

Are there any resources you recommend for parents whose newborn may need to be on oxygen?

Yes, I have a handout that I provide to all families whose infants are on oxygen. 

Are there any red flags or signs that the newborns’ oxygen may not be high enough when they are sent home? Is there anything parents should look out for? I know that you mentioned the oxygen level needs to be as low as 75% before there are any signs of concerning central cyanosis.

No, there really are no clinical signs. A company called Owlet produces a sock for the newborn’s foot that monitors oxygen saturation. I am not sure how accurate this is, but if the parents really want to do something to monitor the oxygen level, this could be a way to do so. It is pretty expensive. On an aside, we are currently in communication with this company regarding future opportunities to conduct research using their product with regards to newborn oxygen saturation at higher elevations, so stay tuned for more developments on this topic.

Are there any risks to starting the infant on oxygen?

No, not at the level that these newborns are sent home on. In premature infants, there is a risk associated with oxygen therapy for eye and lung disease. However, these premature infants are placed on very high flow rates and positive pressures. The damage is actually caused by the pressures of the oxygen being too high. This is not the case for the newborns that we place on oxygen.

Are there any risks to infants or children growing up at high altitude?

Yes, there is some evidence of a very slight increased risk of pulmonary hypertension, but this is very rare.

Thank you so much for taking the time to discuss this, Dr. Chris!

References

  1. Ravert P, Detwiler TL, Dickinson JK. Mean oxygen saturation in well neonates at altitudes between 4498 and 8150 feet. Adv Neonatal Care. 2011 Dec;11(6):412-7. doi: 10.1097/ANC.0b013e3182389348. Erratum in: Adv Neonatal Care. 2012 Feb;12(1):27. PMID: 22123474.
  2. Morgan MC, Maina B, Waiyego M, Mutinda C, Aluvaala J, Maina M, English M. Oxygen saturation ranges for healthy newborns within 24 hours at 1800 m. Arch Dis Child Fetal Neonatal Ed. 2017 May;102(3):F266-F268. doi: 10.1136/archdischild-2016-311813. Epub 2017 Feb 2. PMID: 28154110; PMCID: PMC5474098.
  3. Bakr AF & Habib HS, Normal Values of Pulse Oximetry in Natewborns at High Altitude. Journal of Tropical Pediatrics 2005; 51(3) 170-173.
  4. Qi HY, Ma RY, Jiang LX, et al. Anatomical and hemodynamic evaluations of the heart and pulmonary arterial pressure in healthy children residing at high altitude in China. Int J Cardiol Heart Vasc. 2014;7:158-164. Published 2014 Nov 12. doi:10.1016/j.ijcha.2014.10.015
  5. Remien K, Majmundar SH. Physiology, Fetal Circulation. [Updated 2020 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539710/
  6. Thilo EH, Park-Moore B, Berman ER, Carson BS. Oxygen Saturation by Pulse Oximetry in Healthy Infants at an Altitude of 1610 m (5280 ft): What Is Normal? Am J Dis Child. 1991;145(10):1137–1140. doi:10.1001/archpedi.1991.02160100069025

Austin Ethridge is a second-year physician assistant student at the Red Rocks Community College Physician Assistant Program. Originally from the Colorado front range, Austin attended the University of Northern Colorado where he obtained both a bachelors and masters degree in chemistry prior to attending PA school. In his free time, Austin enjoys spending time with his friends and family, reading, and cycling.

WMS Blog Entry No. 5: Advances in Frostbite, a Synopsis of Dr. Peter Hackett’s Lecture

Frostbite is an injury caused by freezing of the skin and underlying tissue. The main pathophysiology of frostbite is ischemia. Basically, where there is blood flow there is heat and where there is no blood flow there is no heat to that area. The vasoconstriction and loss of blood flow to the skin predispose the skin to becoming frozen. Heat transfer depends on blood flow and blood flow depends on sympathetic nerve tone. In our extremities, there are only nerves that cause vasoconstriction. Exposure to cold or a drop in the body’s core temperature can induce vasoconstriction from these sympathetic nerves in which decreases the amount of blood flow to the extremities to keep the central aspect of the body warm and central organs well-perfused to help to maintain the body’s core temperature.

Frostbite usually occurs in the apical areas of the skin also called glabrous, which is Latin for smooth because these areas have no hair. These areas include the face, palmar surface of the hand, and the plantar surface of the foot. These areas of the skin are rich in arteriovenous anastomoses, which are low-resistance connections between the small arteries and small veins that supply the peripheral blood flow in the apical regions of the skin. These anastomoses allow the blood to flow into the venous plexus of the skin without passing through capillaries, and play a major role in temperature regulation.

Causative factors of frostbite include inadequate insulation, circulatory compromise, dehydration, moisture, trauma, and immobility. All of these factors in combination can result in frostbite.

The behavioral risk factors include mental illness, alcohol/drug use, fear, apathy, and anxiety. All of these risk factors can contribute to frostbite, generally, from poor self-care.

Frostbite is said to kill twice during its two phases that occur. The first phase is the frozen phase in which ice crystals form in the intracellular compartment at about 29 degrees Fahrenheit. These ice crystals will suck the fluid out of the endothelial cells and become enlarged causing the endothelial cells to lyse from dehydration and interrupt microcirculation. The second phase is the rewarming phase in which the skin thaws and is at risk for microthrombi production and necrosis due to prolonged injury to those endothelial cells.

The usual phase at which we see frostbite in a clinical setting is after thawing, in which the skin looks flushed pink, red, with the appearance of blebs that form one hour to twenty-four hours after thawing. These blebs can rupture spontaneously in 4-10 days and shortly after, a cast-like eschar forms. Then the eschar usually sheds in 21-30 days.

Deep Frostbite

Frostbite is classified based on the depth of tissue damage, from superficial with no tissue damage being mild and deep tissue damage including muscle, bone, or tendon being classified as severe frostbite. The mildest form of frostbite is called frostnip. Frostnip is freezing of the skin but there is no actual freezing injury and doesn’t cause permanent skin damage.

Stages of Frostbite

What can you do in the field for Frostbite?

It is important to provide supportive care with IV or PO hydration to prevent dehydration. If the affected area is frozen with no imminent rescue, it is recommended to thaw the area with warm water and try to avoid refreezing. You can give NSAIDs, such as Ibuprofen, 400 mg every 8 hours, or ketorolac 30 mg IV. If the person is at altitude and their oxygen saturation is low you can provide oxygen. However, the individual must be taken to the nearest hospital for further treatment, especially in cases of severe frostbite.

New research studies have been exploring the use of thrombolytics in the treatment of frostbite. Many of the research studies have shown that IV TPA or iloprost may be of benefit to administer in a hospital setting. However, iloprost is not approved for IV use in the United States and other prostacyclins have not been studied for the use of frostbite as of yet. There are current literature and guidelines that have been published for the prevention and treatment of frostbite, however, more research is needed to further support standardized treatment of all patients with frostbite with thrombolytic therapy. Hopefully, these new studies will encourage more research into using thrombolytics and prostacyclins for frostbite.

In the meantime, it would be best to stay warm to prevent frostbite. Tips to help in frostbite prevention include:

  • Limit time you’re outdoors in cold, wet, or windy weather. Pay attention to weather forecasts and wind chill readings. In very cold, windy weather, exposed skin can develop frostbite in a matter of minutes.
  • Dress in several layers of loose, warm clothing. Air trapped between the layers of clothing acts as insulation against the cold. Wear windproof and waterproof outer garments to protect against wind, snow, and rain. Choose undergarments that wick moisture away from your skin. Change out of wet clothing — particularly gloves, hats, and socks — as soon as possible.
  • Wear a hat or headband that fully covers your ears. Heavy woolen or windproof materials make the best headwear for cold protection.
  • Wear socks and sock liners that fit well, provide insulation, and avoid moisture. You might also try hand and foot warmers. Be sure the foot warmers don’t make your boots too tight, restricting blood flow.
  • Watch for signs of frostbite. Early signs of frostbite include red or pale skin, prickling, and numbness.
  • Eat well-balanced meals and stay hydrated. Doing this even before you go out in the cold will help you stay warm.

Lauren Pincomb Apodaca is a second-year Physician Assistant student in the Red Rocks Community College Physician Assistant Program. Originally from Las Cruces, New Mexico, she graduated from New Mexico State University with a Bachelor of Science in Biochemistry and a Bachelor of Art in Chemistry. After obtaining her undergraduate degrees, she was accepted as a Ph.D. fellow in Pharmacology at the University of Minnesota where she conducted research in a biomedical laboratory doing cancer research. She then realized that she wanted to make a difference in people’s lives through hands-on experience rather than working in a laboratory. She went back to New Mexico and received her certification as a nursing assistant and started from the ground up to reach her ultimate goal of being a Physician Assistant. She has enjoyed living in Colorado and the many outdoor activities that Colorado has to offer. Her favorite are kayaking, fishing, and hiking. She is looking forward to graduating soon.

References:

Hill, C. (2017, December 22). Cutaneous Circulation – Arteriovenous Anastomoses. Retrieved September 27, 2020, from https://teachmephysiology.com/cardiovascular-system/special-circulations/cutaneous-circulation/

Frostbite. (2019, March 20). Retrieved September 27, 2020, from https://www.mayoclinic.org/diseases-conditions/frostbite/symptoms-causes/syc-20372656

WMS Blog Entry No. 4, Part I: Tick Bite Prevention and Proper Removal

Ticks are blood feeding parasites. Ticks are known as vectors because they can transmit different pathogens responsible for several diseases including Colorado Tick Fever, Rocky Mountain Spotted Fever (RMSF), Tularemia and relapsing fever. While there are 27 species of ticks in Colorado, almost all human encounters w/ ticks in Colorado involve the Rocky Mountain wood tick, a tick that only lives in the western U.S. and southern Canada at elevations between 4,000 and 10,000 feet. Another highly prevalent tick is the brown dog tick which is specific to dogs.

Before you go out!

DO:

  • Wear protective clothing! Wearing long sleeved shirts, long pants tucked into your socks and close toed shoes can keep ticks from getting onto your skin, as ticks are usually acquired while brushing against low vegetation.
    • wear light colored clothing, as this makes it easier to find ticks that have been picked up
    • Treat clothing w/ permethrin as this can help kill or repel ticks for days to weeks! Do not apply directly to skin.
  • Use Tick repellent. This includes the well-known DEET along with picaridin, IR3535 and oil of lemon eucalyptus
    • Repellent can be applied either directly to skin or to clothing, AND is most effective if applied to the lower body that is likely to come in contact with ticks first!
    • If applying repellents to skin:
      • DO NOT use high concentration formulas on children (DEET concentration > 30)
      • AVOID applying repellents to your hands or other areas that may come in contact with your mouth
      • DO NOT put repellent on wounds
      • ALWAYS wash skin that has had repellent on it.
  • Remember: Dogs can get ticks too! Don’t forget to consult your veterinarian about how to protect your furry friends against ticks.

When you go out: DO NOT assume that you won’t get bit.

  • Avoid tick habitat
    • Ticks are most active in spring and early summer and are concentrated where animal hosts most commonly travel, including areas of brush along field and woodland edges or commonly traveled animal host paths though grassy areas.
      • DO try to avoid exposure in these areas by staying in the center of marked trails when hiking to avoid brushing vegetation that ticks may be perched on waiting for you!
    • If possible, avoid these sites during tick season.
    • If you live in known tick territory, you may even get a tick bite in your own backyard! Decrease this risk by creating a tick-free zone around your house by keeping your lawn mowed, eliminating rodent habitats (wood or rock piles) around your house, and placing wood chips between your lawn and tall grasses or woods.

After coming back inside

  • Perform a tick check which includes botha visual and physical inspection of your entire body, as well as your gear and pets. Because ticks take several hours to settle and begin feeding, you have time to detect and remove them. You tend to not feel ticks because their saliva has histamine suppression and analgesic effects. Ticks like warm, moist and dark areas but can latch anywhere.
    • Examine your scalp, ears, underarms, in and around the belly button, around the waist, groin/pubic area, buttocks and behind your knees.
    • If camping, perform tick checks daily on humans AND pets, making sure to examine children at least twice daily. Again, pay special attention to the head and neck and don’t forget to check clothing for crawling ticks.
    • Shower and wash your clothes after returning home from the outdoors.

If you or a family member get bit by a tick: DO NOT PANIC, and DO NOT immediately rush to the emergency room! If the tick has been attached for less than a day, the chance of the tick transmitting one of these diseases is low. Removing ticks can be tricky, as they use their mouthparts to firmly attach to the skin.

Best method for tick removal -> remove as quickly as possible!

1. Grasp the tick with fine tipped tweezers as close to the skin as possible. If tweezers are not available, use a rubber gloved hand or place tissue or thin plastic over the tick before removing it to avoid possible transmission of disease.

2. Pull tick SLOWLY and with STEADY PRESSURE STRAIGHT away from the skin

  • DO NOT:
    • Crush, puncture, twist or jerk the tick as you remove it. This may increase risk of the tick regurgitating infected body fluids into the skin or leaving mouthparts in skin

3. After the tick is removed, disinfectant the attachment site on skin and WASH YOUR HANDS. Dispose of the live tick by placing in a sealed bag/container and submersing it in alcohol, then wrapping it tightly and crushing it in duct tape, OR flushing it down the toilet.

  • DO NOT:
    • crush the tick in your fingers
    • try to suffocate the tick still on the person by covering it with petroleum jelly OR touching it with a hot match to suffocate -> these methods can cause the tick to burst and INCREASE time the tick is attached, as well as making the tick more difficult to grasp

Remember: the goal is to remove the tick quickly from the host as opposed to waiting for it to detach on its own.

If you remove the tick and are worried, you can always put the tick in a sealed container with alcohol and bring the dead tick to your medical provider.

If you develop a rash or flu-like symptoms (fever, fatigue, body aches, headache) within several weeks of removing tick, see your medical provider and tell him/her about the recent tick bite, when it occurred and where you acquired the tick.

Remember: These diseases are very treatable if caught early enough!

Graphic taken from https://www.cdc.gov/ticks/pdfs/FS_TickBite-508.pdf

Stay tuned for next month’s explanation of the tick life cycle and tick-borne diseases in the high country!

References

1. Colorado Tick and Tick Born Diseases fact sheet. https://extension.colostate.edu/topic-areas/insects/colorado-ticks-and-tick-borne-diseases-5-593/ Accessed on 8/8/20

2. Peterson J., Robinson Howe. P. Lyme Disease: An Uptick in Cases for 2017. Wilderness Medicine Magazine: https://www.wms.org/magazine/1213/Lyme-Disease. Accessed 8/8/20

3. Do’s and Don’t’s of Tick Time: https://awls.org/wilderness-medicine-case-studies/dos-and-donts-of-tick-time/ Accessed 8/8/20

Laurie Pinkerton is a 3rd year Physician Assistant Student studying at Drexel University in Philadelphia, PA. Originally from Northern, VA, she graduated from the University of Mary Washington in Fredericksburg, VA with a degree in Biology in 2014. She moved to Keystone to live that ski life and stayed for 2 years, working as a pharmacy tech at Prescription Alternatives and as a medical assistant at Summit Cardiology. Prior to starting PA school, she moved to Idaho where she learned about organic farming and alternative medicine.  She has loved every second of being back in Summit County and learning here at Ebert Family Practice. She looks forward to practicing Integrative Medicine in the near future.

WMS Blog Entry No. 3: Pre-acclimatization, A Synopsis of Dr. Peter Hackett’s Lecture

What is pre-acclimatization? It is a process of adjusting to a new climate, usually higher elevation, reducing hypoxemia in high altitude settings in turn saving time, money, and most importantly, reducing altitude sickness. It can also allow for better sleep/comfort and physiological/cognitive performance at a high altitude. Acclimatization is a time-dependent process as over 5,000 genes are impacted by a large shift in elevation affecting ventilation, plasma volume, and hemoglobin mass, among other things. The whole process is not completely understood, but one key element is the hypoxic ventilatory response (HVR). HVR is activated by the aortic artery baroreceptors, as oxygen in the blood reduces it triggers an increase in respiration. This happens immediately as you ascend in altitude and maximizes at 7-14 days. Arterial oxygen increases by an increase in ventilation/saturation and also by dropping plasma volume, increasing hemoglobin concentration, and then later on, increasing overall Hgb production which in theory, overall decreases altitude sickness.

So how can you prepare yourself or pre-acclimatize?

Some of the better-known methods are spending time at higher altitudes prior to your destination, using a hyperbaric or normobaric chamber, blood doping, hypoxic exercise training, and a few pharmaceutical methods. All of these are options, but the key question is, which ones truly work?

Pre-acclimatization with actual altitude is the most useful. Generally speaking, you would pick your maximum sleeping altitude at your destination and slowly work your way towards that altitude. You pick an ascent profile which preferably would be spread over a week or more to be most useful. This pre-acclimatization should be completed no more than 1-2 weeks prior to your destination so that any pre-acclimatization gained doesn’t wane prior to your trip.

Simulated altitude is another option which includes hypoxic tents, hypoxic rooms/homes, hypoxic exercise chambers, and hypoxic masks. Out of these four, hypoxic tents or hypoxic rooms/homes, where exposure is over a long duration, are by far the most effective. Hypoxic masks and exercise chambers are not very effective as their short duration does not give the body enough time to make the proper adjustments and although might be beneficial in respiratory muscle training/performance, do little in the way of pre-acclimatizing your body. Studies show more benefit from hypobaric hypoxia training vs normobaric hypoxia training but keep in mind studies are very limited and warrant much further research. Overall, simulated altitude minimum requirements look to be somewhere in the range of 1 week of exposure, 7 hours per day, and a minimum effective altitude of 2200-2500 m and being no more than 1500-2000 m below your target sleeping altitude. Shorter term protocols can attenuate altitude sickness but not the incidence some studies suggest. As to why hypobaric methods are more effective than normobaric methods, no one really knows yet and more research is needed.

Changing your living destination to something at a much higher elevation and exposure over years or moderate altitude residence (MAR), is the most effective method according to some studies, but this is far from feasible for most. There are studies to show epigenetic changes for those who relocate to higher elevations for long periods and these appear to be much less than those who have genetically adapted to higher elevation over generations but still more effective than the previous mentioned short-term options.

Hikers often camp at the Angel of Shavano campground before ascending Mt. Shavano, one of Colorado’s famed fourteeners.

Oxygen saturation is maximal at 11 days of exposure to a specific elevation. Diamox (acetazolamide) increases ventilation and can help with acclimatization but there isn’t much data on how using this pharmaceutical compares to other methods mentioned. World-renowned high altitude expert and pioneerDr. Peter Hackett theorizes that it may fall just short of MAR, but again, more research is needed. Short-term altitude exposure shows benefits at 7 days but a longer exposure such as 15 days has been shown to be much more beneficial.

Blood doping with EPO can be somewhat effective over a 4+ week treatment and can potentially decrease AMS and potentially increase exercise performance but the data is limited and conflicting on this. Also, it appears that it is only effective up to 4,300 m but not beyond that as arterial oxygen content is not the determining factor for sleep and cognition performance at high altitudes but rather oxygen delivery which is affected by hematocrit and viscosity of blood.

Hypoxia inducible factor (HIF) is a regulatory factor in cells that respond to a reduction in oxygen, causing changes in about 5000 different genes to help the body adjust to meet oxygen requirements. It is suggested that we could pharmaceutically activate this factor prior to destination in order to acclimatize the patient allowing for less complications and better results at higher elevations. Currently there are some drugs in trials but nothing specifically FDA approved.

Overall, data and studies are limited but the most effective current pre-acclimatization method is long-term altitude training (real or simulated). If possible, plan your ascent trip to be slow and steady to obtain best results with the least amount of complication.

Joel Miller is currently preparing to graduate from Red Rocks Community College’s reputable Physician Assistant program this Fall. He has been a resident of Colorado for four years where he has immensely enjoyed the outdoors camping, fishing, hiking, hunting, and exploring Colorado’s wide variety of breweries.

WMS Blog Entry No. 2: Long Distance Backpacking, the Wisdom of Dr. Sue Spano

Graduate of Temple University School of Medicine, Director of Wilderness Medicine Fellowship at University of California San Francisco Fresno Department of Emergency Medicine, Sue Spano, MD, FACEP, FAWM presented twice this year at the Wilderness Medicine Society’s annual (virtual) conference. Boasting the experience of about a thousand miles of the Pacific Coast Trail in Oregon and California and other recreational excursions, she shared a wealth of advice and personal recommendations for long distance backpacking.

To put it all into perspective, she referenced the Pacific Coast Trail (PCT), John Muir Trail (JMT) and the Appalachian Trail, each covering 2650 mi, 211 mi, and 2200 mi respectively. These are trips that last, easily, months. The general time frame for many of her recommendations is about five to six months.

Not surprisingly, the issue of weight comes up frequently for travelers. There are a number of studies done on this, from body mass index to base pack weight, and every ounce counts. While fitness level does not directly correlate to the incidence of injury, increase in BMI does correlate directly to increased risk of illness, injury, and trail evacuation. It is notable, however, that in a poll, about 2/3 of those hiking the PCT and well above those on the JMT trained before embarking on the trail, and most of them considered themselves to be “above average” in their level of fitness (7 or 8 on a scale of 1 to 10).

Although Dr. Spano does recommend carrying backups of three things — lighters, water treatment systems, and first aid — when it comes to base weight, there are several items that may be worth a little more investment for fewer ounces. Right off the bat: trail runners over boots. The mere difference in ounces becomes significant after so many miles, and the flexibility of softer shoes helps prevent a lot of discomfort (blisters, for example). She also notes that trail runners are more breathable and dry more quickly, sharing that she doesn’t typically bother to take them off to cross water or in snow as they will dry right on your feet along with your socks. It would be interesting to hear accounts of the footwear of preference on the Colorado Trail, where elevations are frequently higher and there may likely be more snow in general.

In another poll, 21.8 lbs was the base weight carried by packers, most of whom would have carried less in hindsight. This can be achieved by investing in lighter backpacks, tents, hiking poles, sleeping bags and sleeping pads, specifically. ULA Equipment out of Logan Utah makes an ultra-light pack that Dr. Spano prefers, “no conflict of interest”, just her personal favorite.

Skip the toothpaste, Spano urges. It doesn’t actually clean your teeth, so you might as well just brush with water.

Something else we’re seeing more and more of on distance excursions is tents that incorporate hiking poles as tent poles. Hiking poles themselves are recommended more and more as well, as they distribute more weight away from your legs.

Toilet paper must be packed out with you on much of the trail these days! Thus, the rise of the “backcountry bidet”, which you can make yourself by poking holes in the cap of a plastic liter water bottle. “You come out feeling like you had a full shower,” Spano testifies, and the water you use does not have to be filtered or potable.

Water! Know where your next water source will be. “Camel up at water sources … When you get to a water source, spend some real quality time there soaking your feet, cleaning your bandana, drinking as much water as you possibly feel like you want. Because the only time that your water is going to be ice cold is when you’re at that stream. Anything that you carry with is going to get really warm … Your easiest way to carry water is in your belly.”

When it comes to long distance backpacking, one of the finest pieces of advice Dr. Spano offers is that you should always be upgrading and optimizing your strategy:

“A person who hasn’t changed their backpacking practices in the last 10 years is not a person that I would really want to backpack with. A person who practices medicine the same way they did 10 years ago is not someone I want to practice medicine with. You should always be improving your gear, improving your behaviors, improving the way you approach the same challenge so that you’re a better backpacker as a result.”

Her hour-and-a-half practicum is available on the Wilderness Medicine Society website.

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.

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.”

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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.