Recognizing and preventing altitude sickness

Recognizing and preventing altitude sickness

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I remember the first western hunt I went on. I was black bear hunting at about 7,000 ft. in the Bitterroot Mountains of Idaho. Not exactly a high-altitude hunt. But I’m a flatlander from Minnesota who hadn’t been to the mountains in years. Having spent a lot of time adventuring in the mountains growing up, I knew elevation could make things difficult. But as a washed-up collegiate athlete who still worked out, I figured it’d be no more than a minor inconvenience. I was wrong.

Symptoms of altitude sickness

I had planned to camp on the shores of a small lake eight miles from my truck. But by the time I was five miles in I knew I wasn’t going to make it. Fortunately, there was an old forest service cabin near me. But, even though the cabin was only 500 yards up the hill from me, I was so exhausted from the hike I had to take a half hour nap—not just a break—before I could bring myself to continue on.

Once I set up camp, I knew I needed to eat a good meal to facilitate recovery, but between the fatigue and a mild headache, eating was the last thing I wanted to do. Finally, after force-feeding myself, I settled in for a good night’s sleep, only to toss and turn all night, hardly more than dozing in fits and starts.

As it turns out, fatigue, shortness of breath, headache, loss of appetite, and trouble sleeping are all symptoms of Acute Mountain Syndrome (AMS)—commonly called altitude sickness—along with dizziness, nausea, and vomiting.

The real danger

Although I had only a mild case of AMS, which was miserable but no real threat to my health, altitude sickness is not something to simply be “toughed out.” Severe cases of AMS can develop into high-altitude pulmonary edema (HAPE) and/or high-altitude cerebral edema (HACE), both of which can be life threatening.

HAPE is a buildup of fluid in the lungs, which can result in breathlessness even at rest and a persistent cough that produces a white or pink frothy substance in addition to the symptoms mentioned above.

HACE is a buildup of fluid in the brain and is the most severe type of AMS. It can also be the most difficult to notice until it’s too late for self rescue, as the symptoms can also be interpreted as plain exhaustion. The early signs of HACE include clumsiness and difficulty walking, confusion, and a severe headache that doesn’t get better with medication. If the condition continues to get worse, symptoms will progress to a total inability to walk and eventually a coma. At this point the patient will need intervention by medical professionals to recover—they need a hospital immediately. Unfortunately, in this condition, they will be unable to self rescue; you will have to carry them off the mountain yourself or call for a rescue.

If any of the symptoms for AMS develop, you should not continue to climb in elevation; instead, allow yourself to acclimatize for at least a day and let the symptoms abate. If moderate symptoms develop, you should descend 1,000 feet and rest for a day. If severe symptoms develop or symptoms continue to worsen, descend further and seek professional medical help.

Adjunctive treatments for AMS and HACE would be to begin a dose of dexamethosone or acetazolamide. For HAPE, a dose of Nifedipine can be started. In all cases, supplemental oxygen can be used, if available, to help raise blood oxygen levels in the event descent is not immediately possible due to weather or other factors.

As a real-life example of a moderately severe case, on an elk hunt last fall, I became fairly concerned with one of my hunting partners. He lives at around 600 feet of elevation and he had never been to the mountains before. We set up our base camp around 10,500 feet in the late morning and lounged around until lunchtime. Climbing more than 1,000 feet in elevation on a five-mile hike his first day ever in the mountains, it was not surprising that he was absolutely exhausted, a little short of breath during the hike, and complaining of a mild headache. I grew concerned, though, at lunch, when I said something to him in the midst of a larger conversation with our other hunting partner, and he didn’t respond for almost a full minute—long after the conversation had moved on. It took his brain almost a minute to process a simple statement and come up with a reply. In my view, he was was on the brink of HACE, but since this was the only moderately severe symptom he was experiencing and we wouldn’t be climbing any higher, I decided to just keep a close eye on him and force him to drink lots of water. After a nap that afternoon, his faculties had much revived, and within a few days all of his symptoms of AMS had resolved.

Table of AMS severity level from the Wilderness Medical Society paper Wilderness Medical Society Clinical Practice Guidelines forthe Prevention and Treatment of Acute Altitude Illness:2019 Update

In the above table, you will notice what is called the Lake Louise AMS score. This is an excellent checklist of symptoms and symptom severity to help you perform a self assessment. You can find a copy of the assessment here.

*I am not a medical professional and nothing in this article should be construed as medical advice. Examples in this article are for illustrative purposes only.

How to prevent and reduce altitude sickness

The best way to avoid altitude sickness is to ascend slowly over the course of multiple days, allowing your body to acclimate to the lower pressure, and thus less oxygen, found at high elevations. And drink lots of water. Unfortunately, it’s often not feasible to take three days to slowly hike up to your hunting spot.

Whether or not you slowly ascend, it is critical that you drink lots of water. At high elevations you will become dehydrated more quickly, especially if you are not acclimated to the elevation, due to increased respiratory rate and the typically low humidity at elevation. Further, dehydration can make diagnosis of AMS difficult because many of the symptoms are the same. Finally, the more blood volume you have, the more oxygen your body can carry.

If you do not have time to ascend slowly or if you have had problems with AMS in the past, there are a few pharmaceutical options you may want to contact your doctor about. The CDC recommends taking acetazolamide or dexamethosone prophylactically for anybody who is climbing to 9,200 feet in elevation in one day. Acetazolamide is the preferred prophylactic during ascent because it actually helps to speed acclimatization, while dexamethosone is a more effective treatment for relieving symptoms. However, it is not generally recommended for both to be taken at the same time. If you are more at risk of HAPE for cardio-pulmonary reasons, you may want to take nifedepine prophylactically.

Finally, the last thing you can do to prevent altitude sickness is to increase your body’s ability to intake and utilize oxygen. To increase your body’s ability to utilize oxygen, you will want to increase your VO2 max. VO2 max is a measure of your maximum rate of oxygen consumption. The higher your VO2 max is, the more oxygen in each breath you can consume and utilize. To increase your VO2 max, you will want to do things like run sprints and circuit train. If you want a plan that has everything you need to increase VO2 max already figured in, check out The Ultimate Pack Workout program.

Similar to increasing your VO2 max, when you’re on the mountain, increase the amount of oxygen available to yourself be breathing deeper and faster. It may sound hokey, but really focusing on the tempo and depth of your breathing makes a world of difference. It’s simple math, really: If every breath is a little deeper than normal, and if you take more breaths every minute, there is more oxygen available to your body.

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