Altitude Illnesses

Altitude is measured by feet (or meters) above sea level. The important thing to remember is that the partial pressure of oxygen decreases with the increase in altitude. In other words, the higher up you are, the less oxygen is available for breathing. This could be a bummer. The signs and symptoms associated with altitude sickness are directly and indirectly related to hypoxia. Because we are all different, we all respond differently to altitude and therefore each patient can present with unique sequelae. Some people are just more susceptible to altitude illness.

rescue_operation_wallpaper_landscape_nature_wallpaper_1600_1200_1180The Alphabet

HVR: Hypoxic Ventilatory Response

HVR is the result of a decrease in blood oxygen saturation and ventilation after a few hours at altitude. Altered fluid homeostasis also occurs – which means that fluid is redistributed from the intravascular to the intracellular and extracellular spaces – and the result can be peripheral and/or pulmonary, and/or cerebral edema.

HACE: High Altitude Cerebral Edema

HAPE: High Altitude Pulmonary Edema

HAFE: High Altitude Flatus Expulsion

AMS: Acute Mountain Sickness

AMS is a continuum of signs and symptoms that can range from loss of appetite and headache to coma and death. AMS is generally described as mild, moderate or severe.

Mild AMS: Patients may experience headache relieved by rest and medication, nausea, loss of appetite and insomnia. Nothing is visible on physical exam. Advise the patient to stop the ascent until the symptoms disappear. The goal is to hydrate, hydrate, hydrate and eat – in spite of the anorexia

Moderate AMS: These patients may complain of headache not relieved by rest or medication, nausea and vomiting, shortness of breath, fatigue and weakness at rest, loss of appetite, and insomnia. Most of the symptoms are caused by hypoxia, so supplemental oxygen is a must. Patients should descend 1000 – 2000 feet.  Ski patrol teams and ambulances operating in the mountains encounter these patients with relative frequency.

Hydration is also a key to treatment. If vomiting continues, prochlorperazine (Compazine®) can be administered as an antiemetic. Acetazolamide (Diamox®) may also be helpful. Watch these patients for worsening of symptoms.

Severe AMS: These patients exhibit all of the signs and symptoms of moderate AMS and: sometimes ataxia, dyspnea at rest, tachycardia, and as HAPE (high altitude pulmonary edema) begins patients may begin with a persistent dry cough followed by rales upon auscultation. Late in severe AMS some patients experience blood tinged sputum. Hypoxia worsens with tachycardia. AMS occurs late in AMS (altered mental status occurs late in acute mountain sickness. HACE (high altitude cerebral edema) may also occur. Proper care is Oxygenation and descent, with administration of dexamethazone (Decadron®) for HACE, acetazolamide (Diamox®) and nifedipine (Adalat®) for HAPE.

Acetazolamide (Diamox®) – What is it and what does it do?
It is a diuretic that indirectly causes enhanced ventilatory acclimation and decreases cerebral spinal fluid production. It is indicated for patients with moderate or severe AMS and for rescuers making rapid ascents to reach these patients. Since it is a diuretic, it causes polyuria and possibly dehydration if adequate fluid intake is not maintained.

Dexamethazone (Decadron®) – What is it and what does it do?
It is a steroid with anti-inflammatory effects. While it is effective at treating AMS and HACE, the symptoms can rebound once the medication is stopped.

So, now we have HAPE, HACE and just what is HAFE? High altitude flatus expulsion. Supposedly, intralumenal bowel gas expands with decreased barometric pressure causing flatus. If necessary, simethicone (Phazyme®, Gas-X®) can be used to treat it.


Understanding how to treat patients with AMS is important, but understanding how to protect the rescuer and how not to become a patient is also a priority. Be a rescuer…don’t become a victim.


Burke, TG. Altitude illness. Prehospital Emergency Medicine Secrets. Hanley and Belfus, Philadelphia, 1998.

Fogerty, WW. (ed): Wilderness Medical Society Practice Guidelines for Wilderness and Environmental Emergencies. Merrillville, IN. ICS Books, 1995.

Hackett, PH, Roach, RC: High altitude medicine. In Auerbach, PS (ed): Wilderness Medicine: Management of Wilderness and Environmental Emergencies, 3rd ed. St. Louis, Mosby, 1995, pp 1-37.

Hackett PH, Rennioe D: The incidence, importance and prophylaxis of acute mountain sickness. Lancet 2(7996):1149-1155, 1976.

Johnson, TS, Rock, PB: Acute mountain sickness. N ENgl J Med 319:841-845, 1988.

Larson EB, Roach, RC, SChoene RB, Hornbein, TF: Acute mountain sickness and acetazolamide. JAMA 248:328-332, 1982.

Tilton B (ed): Wilderness Medicine Handbook, 2nd ed. Pitkin, CO, Wilderness Medical Institute, 1997.

10 Common Wilderness Survival Mistakes

Drinking Urine.

Urine contains dissolved solids (urea, uric acid, creatinine and ammonia), inorganic substances (sodium, chloride, calcium, potassium, phosphates and sulfates) and bacteria (often from the surrounding skin). Urea is a natural diuretic and water is required to dissolve and excrete it from the body. As dehydration increases so does the amount of urea that needs to be processed. In other words, drinking urine dehydrates you more quickly than drinking nothing at all.

Trying to snare a deer.

Imagine a 150- to 200-pound animal with its neck or leg stuck in a snare. Not only will you be causing it a lot of unnecessary pain, you’re left with a problem: How are you going to kill it? Unless you have a firearm, you’ll likely get hurt trying to put the animal down. In a survival setting, it is much safer and more efficient to focus on small game like rabbits, squirrels and rats.

Eating a raw bug.

Although bugs, like grasshoppers, can be a great food source, they are known to carry parasites and should be cooked before consumption. In addition to killing the parasites, cooking a bug usually makes it more palatable. Better to have a stew made from slugs, maggots, grubs or cockroaches than to eat them raw.

Eating food when you don’t have water.

You can live weeks without food and only days without water. Your body needs water to digest food, so eating when you don’t have water will only accelerate dehydration. In a long-term survival situation, of course, food will become necessary, so it is important to establish your camp near a location that provides both water and food.

Wearing a wet base layer.

The layer of clothing closest to your skin–which should usually be made out of a material like Polypropylene–should always be dry. Polypropylene wicks moisture away from the body, making it a great base layer. Wearing it when wet, however, is a mistake, as it will have a major impact on how quickly your body loses heat (you lose body heat 26 times faster when you are wet then when dry). For best use, keep the base layer dry. If it gets wet, change it or take it off, wring out the moisture, and put it back on.

Choosing fire over shelter.

Building a fire takes time and even if you get one going, you’ll be up all night adding fuel to the flames. Fire is the third line of personal protection (it comes after clothing and shelter) and shouldn’t be considered until a shelter that protects you from wind and moisture has been established. It is okay, however, to use a small fire to warm you during the shelter-building process.

Traveling when you don’t know where you are.

If you don’t know where you are, how will you know where to go? Travel should only be considered if your location doesn’t meet your needs, rescue doesn’t appear imminent and you have the navigational skills to get from one point to another (know where you are and where you are going).

Drinking alcohol to stay warm.

Although a sip of whiskey may make you feel warmer, it actually promotes hypothermia. Alcohol causes blood vessels to dilate, which increases blood flow to the surface of the skin and allows the outside cold to pilfer heat from the body core (brain and vital organs). Instead of alcohol, drink water and wear appropriate clothing!

Believing the sun rises in the east and sets in the west, relative to your position.

The sun’s path changes daily, reaching its northern and summer extremes on June 21 (summer solstice) and December 21 (winter solstice). The sun passes directly over the equator during the equinoxes (March 21 and September 23). Unless you are on the same latitude as the sun’s path, it will not rise or fall directly east or west of your location. In fact, it can be off by a large percentage, making navigation by sun next to impossible.

Taking your hat of when you are hot.

You lose 50 to 75 percent of your body heat through your head. Heat is calories and calories provide the body with the energy needed for daily tasks. It is better to slow down or remove a middle layer of clothing (between your coat and T-shirt) than to work up a sweat and waste precious calories.