Warning: Long post.

When I was a pilot in the Air Force, I got a lot of training on altitude sickness. Before saying anything, I wanted to brush up on my knowledge.

Many people think there is only one cause of altitude sickness. Hypoxia. Which is a shortage of oxygen to the brain. This can be characterized by shortness of breath like a smoker, or just a discomfort in breathing. Like air is coming in and it's not doing any good. Headaches will likely occur with exposure of a few hours. And vomiting can occur. The solution to hypoxia is simply go to a lower altitude. If a person won't walk, it may help to have them lay with their head lower than their heart. Having them drink something may help as it can be confused with dehydration. Hot chocolate is said to reduce symptoms. I saw it work in just a few minutes. In Colorado, you can legally use pot for medicinal purposes with a license. A few puffs of that may help, too.

But hypoxia isn't likely to kill anyone at reasonable altitudes unless there are other medical problems. What will kill people is the OTHER kind of altitude sickness. It's commonly called the bends which is associated with diving.

The bends is caused by nitrogen coming out of the blood and other liquids in the body when we go up in altitude. Think taking the top off a soda bottle. Most hike too slowly to go up fast enough to cause a problem, or the hills aren't steep enough. But a person who drives to a high trailhead and starts hiking quickly uphill may have a problem.

Think of what happens to a potato chip bag when you bring it up in altitude. It expands a lot and that can happen in litte tissue pockets as nitrogen is released from solution. The problem is, if you get a little tear, the pressure is released and a lot more gas comes out. It's like taking the top off a soda bottle.

The bends has nothing to do with what shape a person is. It's simply their physiology. Backpackers have few problems simply because they move more slowly than a hiker without a pack.

Once a tissue tear occurs, going to a low altitude will not do anything to mend that tear. It will prevent further tears. Unfortunatly, having the person walk down will shake the soda bottle and cause more gas to be released.

It's likely a bad idea to drive from sea level to a trailhead above 4,000 feet and hike hard to 8,000 feet. (The pressure loss per 1,000 feet is higher at lower altitudes.) Simply taking more frequent breaks even if not tired can help. The greater the distance you climb in the car before hiking, the more likely it is you will get a pulminary or cerebral endema unless you take a day to acclimate to the higher altitude. Two days is safer.

How common is an endema? One in a hundred that goes above 3,500 meters will have one if they don't acclimate first. Source - table 25-1

Fred, the reason it's not a problem in planes is the pilots aren't hiking. They are generally sitting still, so the nitrogen doesn't come out of solution. But it CAN happen above 25,000 feet. That's the reason you can't fly above 25,000 feet without a pressurized cabin.

Now, back to hypoxia so an experienced person can tell the difference for themselves. We were taught the FIRST symptom of hypoxia never changes during our lifetime. For me it's a tingling in the fingers. The fancy term is "parethesia." Others have different symptoms. If the first symptom is something other than you personal first symptom, then there is a good chance it's an endema.

Lori, I'm guessing SAR carries oxygen bottles for these types of things as administering oxygen is the first treatment for both. If it's just the bends and no endemas have occurred, it will clear up in an hour or two of using oxygen.

Coughing blood or mental confusion approaching that of a drunk are both causes for extreme concern. Another cause for concern is shortness of breath that doesn't disappear when resting. If the heart rate remains elevated even when resting (above about 110) that is also cause for concern an endema is occuring. If fingers start to turn blue, it's time to panic.

This summer, my son had a pretty good case of hypoxia. He often hikes with a migraine so a headache isn't a good first symptom. But it is his first symptom of hypoxia. We were at about 11,000 feet still about 1/4 mile uphill to our campsite when we got hit with one of those sudden Colorado rainstorms. I saw it coming and called a halt to set up the tent quickly. That's when he had the urge to puke three times. He also had some mental confusion similar to having a couple drinks. He made a video of himself of all things, but I don't think he'd want me to share it.

I was glad I'd practiced setting up the tent myself in less than 5 minutes.

I had him lay down and made some hot chocolate. And he took a few puffs. (It's the only thing that touches his migraines and is a legal prescription.) Within a few minutes, he was fine and ready to eat. Going back down wasn't an option as it was getting close to dark and it was still raining.