Rest In Peace: Maddie / Learn About: AMS (Acute Mountain Sickness)


When word got out that someone on the PCT in this year’s class passed away on trail, I posted on our Instagram. While the official cause of death was not published… there were signs about how Maddie was suffering from Altitude Sickness to some degree after entering the Sierras. With that being said, sometimes in tragedy people learn more about something like AMS which is covered below by Ned Tibbits that I cut and pasted from his Facebook posts. Ned loves to share his experience and knowledge so if it can help someone… he is all for it. So in Maddie’s passing, I will learn more about this so that when it’s time to do our hike we understand it better and know how to improve our situation by understanding the symptoms and also what we can do to help us deal with AMS. The hiker that posted a recap above was also trying to educate other current hikers and future hikers about AMS.

AMS-1 (Acute Mountain Sickness)*:

How much of an issue is Acute Mountain Sickness (AMS), if you haven’t had it before or don’t know, yet if you’re prone to suffering from it?

That’s a very wise and educated question that should be of concern to everyone who desires to travel at altitude…for it can, indeed, disable and get you flown off the hill!

As a former paramedic, 40-year wilderness safety educator, and current SAR hasty team member, I’ve seen a few cases of AMS and have flown a few of my own students (who didn’t expect to suffer from it) out of the Sierra.

As others may tell you, you don’t know if it will be an issue, until it is. You can have hiked at altitude (anywhere above 8,000 feet, typically) your whole life and, suddenly, one day it develops.

The basis of it is hypoxemia (insufficient oxygen in the bloodstream), but the seriousness of it is not necessarily indicated by being out of breath on the trail, but rather, by experiencing altered mentation (your brain doesn’t work right for lack of oxygen), which is often not noticed by the hiker, themselves, but by those nearby (a hiker in a group starts talking strangely, not thinking clearly, moving erratically, nauseous, head-achy, weak, etc.).

It can have a genetic predisposition, where your parents or relatives have suffered from it before, or maybe you’ll be the first in your family to have to deal with it. If you haven’t experienced it, yet, ask if anyone in your family has had it.

Aerobic fitness will help to mitigate it because increased oxygen needed over time will stimulate the production of hemoglobin to bind more oxygen and transport it to your brain. This is what happens slowly when you first get to altitude.

AMS can come on suddenly or gradually. How it manifests (speed of onset and symptoms) in people varies, but the main signs and symptoms are nausea/vomiting, altered speech/thought, and exhaustion/weakness.

The only “cure” is more oxygen, externally, or an increase in your hemoglobin count (to pull oxygen out of the atmosphere and get it to where in your body it is needed). Most people don’t carry bottled oxygen, so they have to descend to higher atmospheric pressures where oxygen will be absorbed easier and faster.

[It’s not that there is less oxygen at altitude, it’s that there is less pressure “pushing” it into your lungs (this does not mean that breathing faster will solve the problem; changing the quantity of air into your lungs doesn’t change the air’s atmospheric pressure (gas-pressure-differential) and, thus, the ease of oxygen absorption. However, good try!).

Once the symptoms start, they may get worse, as your body produces as much hemoglobin as fast as possible (if it can, depending on your overall health) to counter the effects, or it will level off with certain minor symptoms, only, while you rest for a few days, then get going once you feel better and can think straight.

How much of an issue AMS is for you, you won’t know until you expose yourself to the decreased atmospheric pressures at altitude. Where is that? Some feel it at 8,000 feet while many never do at 15,000.

Now, this is just one issue to be aware of when out on mountains of significant altitude. Just remember, when your brain goes a little sideways because of it, you may not know what’s going on – but others can tell when interacting with you! Don’t hike alone.

* These are informal teachings on a specific subject conducted in the virtual classroom for all to appreciate and peacefully enjoin. There will be no criticism of fellow students’ friendly remarks, infighting, or grandstanding on other topics. Let’s help each other learn the subject matter at hand. Fighting and distractions will get you thrown out of class.

I don’t know about all of you, but after the recent, tragic news of a hiker’s death on Forester Pass on May 28th, due to the identifiable and preventable, Acute Mountain Sickness (AMS), I simply haven’t been able to continue with this teaching started on May 17th.

I have been too saddened even to think, grieving for her loss to this invisible villain of altitude. Still, there are other people, either already on-trail or wanting to go up there, soon, who need to understand what’s happening to the human body, what AMS looks like, and how it can be prevented, so I must continue posthaste.

There are two basic causes for the symptoms of AMS,

1. Decreased atmospheric pressure upon the human body

2. Decreased oxygen absorption through the lungs and into the bloodstream

When we travel from sea level and up into the mountains to play, hike, fish, and breathe the fresh air, we go from having a ton of “air” overhead to having less, thus, the sky is clearer and the stars are more sparkly, for example.

Our bodies get used to the amount of atmospheric “weight” around us wherever we live and are very adaptable to changes in this as we go up in elevation, but this process takes time, which, with our busy society and demanding schedules, isn’t so convenient.

21% of our atmosphere is comprised of oxygen, no matter where we are. There isn’t less oxygen at altitude, although that is what many of us believed. There is less pressure overhead and around us as we ascend into “thin air.”

Two things happen within the human body when the pressure outside it drops,

1. Less oxygen is “pushed” across the thin membranes of the lung and into the waiting capillary beds to catch a ride into the body via red blood cells. Five people can exert more pressure to push a stalled car off to the side of the road than can one or two. Think of these people as the atmospheric pressure “driving force” behind the oxygen-car. When the pressure outside the body drops (fewer people pushing the car), less oxygen goes into the body and cell metabolism (function) suffers.

2. As the atmospheric pressure outside the body drops, the pressure inside the body, relatively speaking, increases. The signs of this are the movement of thin, viscous fluids, like plasma, from cells and spaces between the cells to places where they shouldn’t be, like into the lungs (pulmonary edema) and into the cranium (cerebral edema).

[To the professional biologists, nurses, and doctors out there, I’m trying to keep this simple and easy to understand. I know that more is going on that could be mentioned, but let’s leave it at this, for now].

Decreased oxygen absorption across the lung membranes, due to decreased atmospheric pressure at altitude or outside, causes less oxygen-fuel to the cells, who are doing the work of hiking, in this case, and a decrease in cellular performance seen as fatigue, exhaustion, muscle cramping, and simply the inability to function normally results. As cells perform poorly, they make more waste and that doesn’t help, either.

The body reacts by increasing the heart rate to move more of what little oxygen the bloodstream has out to the cellular engines and to pick up waste, say in the form of lactic acid and carbon monoxide, and get it out of the way.

Respiratory rates increase to try to take in more oxygen, but the concentration of it outside the body (21%) hasn’t changed, the driving force has diminished, and the transport mechanism within the bloodstream is only beginning to respond to the altitude change. Breathing faster does not increase your uptake of oxygen from the lungs into the bloodstream, having a better transport mechanism, or more red blood cells do.

Red blood cells are like taxis on a city street outside a train station (your lungs). When the train arrives (every inhalation) and dumps out its passengers (oxygen), the street (the tiny arteries in the capillary beds) gets flooded with people (oxygen) who wait to catch a ride in a taxi (red blood cells) to get to their job sites. If you need to move (via the pumping action of the heart) more people (oxygen) to their job sites, at the cells, you need more taxis or red blood cells! Taxis (red blood cells) are made in the marrow of our bones and these factories respond slower than our schedules demand.

Let’s make this real:

A person of relative fitness leaves the Mexican border and backpacks the Pacific Crest Trail along an undulating path for 700 miles and six weeks to Kennedy Meadows (south), whereupon they begin a quick ascent into the High Sierra.

During those first, physically-trying six weeks, oxygen demand increases, atmospheric pressures remain about the same, and red blood cells are made to meet the demand. All is well, the body is strong, working efficiently, and the hiker is clear-headed.

After about 40 miles north of Kennedy Meadows (south), the hiker climbs to roughly 10,000 feet. During this distance, oxygen demand increases, during this time, few red blood cells are produced, and outside the body, atmospheric pressure decreases.

When the body wants more oxygen, but can’t absorb it, the cells have less oxygen, work poorly, and functions suffer, like clear-thinking, concise speech, speed of processing and movement, fatigue increases (due to increased cellular waste in the bloodstream), and cramping may occur.

When the outside pressure decreases, fluids shift in the body and leak into places where they shouldn’t be, like the lungs (coughing and increased respiratory and heart rates) and brain (delayed mentation and thought, garbled speech, poor balance and fine motor control, headache, nausea, vomiting, and other systemic maladies, like irregular breathing).

Red blood cells (more taxis) are needed to meet the body’s oxygen demands, but this takes time, so rest and inactivity (decreased oxygen need) are required for a period of time. Some people’s bodies respond quickly, so they can recover right there, on-trail, and resume hiking after a few days, while others may not (at least not according to some hiker’s schedules).

For the affected person to continue hiking and, even worse, climb in altitude toward Forester Pass, this demands more oxygen than the body is ready or able to transport, while the rise into thinner air increases the fluid leak into the lungs and cranium. Symptoms of this fluid in the lungs (mentioned above) get worse while fluid-pressure builds on the brain, pushing it down toward the brainstem and affecting control of vital life functions, like respiratory rates, blood pressure, and heart rhythms.

The body needs both oxygen and pressure, both of which can be obtained from a bottle of pressurized oxygen, but most hikers don’t have these readily available (most do not anticipate the need as they’ve never experienced a problem with Altitude Sickness before). The only other way to accomplish this is to descend in altitude to where there is more pressure on the body to drive more oxygen into the bloodstream and those loose fluids back to where they belong.

Ok, class. The test will be on Friday.

* These are informal teachings on a specific subject conducted in the virtual classroom for all to appreciate and peacefully enjoin. There will be no criticism of fellow students’ friendly remarks, infighting, or grandstanding on other topics. Let’s help each other learn the subject matter at hand. Fighting and distractions will get you thrown out of class.

Not all dizziness, headache, and nausea are due to altitude.

When I was working as a pro ski patroller at Heavenly for a few years (where skiers start at 6200 feet, quickly rise to 10,000 feet via tram or chairlift, and wonder why they’re throwing up and have splitting headaches), we, in our assessment and differential diagnosis, had to rule out several possible reasons for those symptoms:

– Altitude (low pressure causing low oxygen)

– Hyper/hypothermia (too hot, too cold)

– Dehydration (low fluids, electrolytes)

– Hypo/hyperglycemia (low/high sugar level in the blood)

– Alcohol

– Exhaustion (hiking too long and too hard)

– Hyper/hypotension (high/low blood pressure)

– Trauma (did they hit their head earlier?)

– Medical history (are they pre-disposed or off their meds?)

– Psychological causes (anxiety about something?)

– etc.

For ascending hikers who might be starting to feel “weird,” abnormally tired and exhausted, slightly headachy, and maybe have an upset stomach, they need to do the same thing – an internal audit of the above possibilities:

– has anyone in my family ever had altitude sickness?

– have I been hiking too hard and am too hot?

– am I dehydrated? (Drink a litre and see how you feel).

– when was the last time I had a big meal? Could I be hungry?

– might my medical history and medications be a part of this?

– could the tumble down the hill this morning be causing this?

– am I just freaking out about Forester Pass (for example)?

* These are informal teachings on a specific subject conducted in the virtual classroom for all to appreciate and peacefully enjoin. There will be no criticism of fellow students’ friendly remarks, infighting, or grandstanding on other topics. Let’s help each other learn the subject matter at hand. Fighting and distractions will get you thrown out of class.

Ned (Mountain Education, Inc.)

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