Notes On Acute Mountain Sickness

Key to acclimatization: Is adequate hydration, adequate nutrition & managing personal comfort through adequate layers lead to acclimatization.

Following extracts are taken from “The Wilderness First Responder” by Buck Tilton, director of Wilderness Medicine Institute of NOLS, USA


Without water there would be no life – at least no life, as you know it…

Water puddles inside every one of your cells, and flows through the microscopic spaces between cells. In water, oxygen and nutrients float to all parts of your body, and waste products are carried away. When your kidneys remove waste from your body those wastes have to be dissolved in water. Digestion and metabolism are water-based processes, and water is the primary lubricating element in your joints. You even need water to breathe, your lungs requiring moisture to expedite the transfer of oxygen into blood and carbon dioxide out of blood. Sweat, as mentioned, is mostly water. The water in your blood carries heat from warmer body parts to cooler areas of your anatomy when you are exposed to cold. In short, if aren’t well hydrated, you won’t be able to stay healthy, maximize your performance, or even maintain joy at being outdoors.

The water in your body, the fluid that keeps you alive and active, leaves you at an alarming rate. Estimates vary widely, but an average person at rest on a normal day loses between two and three liters of water. One to one-and-a-half liters rushes out as urine, and another one-tenth liter in defecation. Moisture is lost from act of breathing, more than half a liter per day, and that rate increases in dry winter air.

Then there’s sweat. The fluid lost in perspiration can climb to one to two liters per hour during periods of strenuous exercise. Compared to watching TV all day, one hour of exercise may demand approximately a 50 percent increase in the amount of water your body uses.

Your thirst mechanism that feeling of ”Gosh, I need a drink of water”, doesn’t kick in until you’re about one to one-and-a-half liters low. Down three to four liters can leave your endurance decreased to 50 percent and your oxygen uptake reduced close to 25 percent…


The medical problems collectively referred to, as “altitude illnesses” is the result of hypoxia, insufficient oxygen in the blood for normal tissue function, a result of the decreased barometric pressure at higher altitudes. When you go up, the barometric pressure goes down, the concentration of oxygen in the air decreases, and the chance of altitude illness climbs.

Since there is a measurable increase in ventilation and decrease in aerobic exercise performance above 4,000 feet elevation, “high altitude” can be said to start at that point. Complications seldom occur, however, below 8,000 feet. In defining terms, consider 8,000 to 12,000 feet as high altitude, 12,000 to 18,000 as very high altitude, and 18,000 plus as extreme high altitude.

The human body will adjust to dramatic changes in barometric pressure, given enough time. Altitude illnesses – which range from mildly disturbing to completely fatal – are determined, primarily, by three factors:

How high the patient goes.

  1. How fast the patient attains a specific altitude, and
  2. Predisposing factors such as genetics and previous upper respiratory illnesses.
  3. Critical to acclimatization is adequate hydration and nutrition.


As mentioned earlier, most people will adjust to altitude given enough time. Staged ascent is the key to acclimatization and, therefore, the key to preventing altitude illnesses.

Adequate hydration is critical to the prevention of altitude illnesses. You should drink enough water to keep your urine output clear and copious.

A high calorie diet is essential for the energy needed to ascend and acclimatize.

Avoid respiratory depressants, such as sleeping pills and alcohol.

…But physical fitness prior to ascent is a bonus in the game of safety and enjoyment. Fitness does not, however, protect against acute mountain sickness.

(Friends: this is just to inform you about these important factors that we would be dealing in on the mountain. I know that there would be a lot of questions in your mind – how does one acclimatize, what food is to be taken, what are the early signs and symptoms that would alert me to start taking extra efforts to stay hydrated/acclimatized, etc. etc.)