rules of Mountain trekking and precautions and science in trekking

Too complicated for me...I go by simple signs, if you feel cold, cover yourself more, Don't push yourself in initial part of trek, and if it is getting dark and you have no place to rest in deep wilderness, you have pretty much done yourself in. Therefore, remember all the wonderful things that happened in your life...it is better to depart with good thoughts.

That works as well

Acute Mountain Sickness (AMS)
Everyone traveling to high altitude is at risk due to lack of oxygen, regardless of age, level of physical fitness, prior medical history, or previous altitude experience. AMS and high-altitude cerebral edema (HACE) are manifestations in the brain, while high-altitude pulmonary edema (HAPE) is that of the lung.
Although at moderate altitude, 2000-3500m, oxygen is sufficient, low partial pressure of Oxygen may result in mild altitude illness. High altitude refers to elevations of 3500-5500m when oxygen is not sufficient and extreme lack of oxygen can occur during sleep, with exercise, or illness. Extreme altitude is over 5500m, above which, successful long-term acclimatization is not possible and in fact deterioration ensues. Individuals must progressively acclimatize to intermediate altitudes to reach extreme altitude.
Acclimatization
The partial pressure of oxygen decreases with ascent to altitude. The breathed partial pressure is still lower because of water vapor pressure in the respiratory airway. At an altitude of 4000m, it is equivalent to breathing 12% oxygen at sea level.
The response to AMS depends on both the magnitude and the rate of onset. The process of adjusting to lower oxygen, termed acclimatization, is a series of compensatory changes in multiple organ systems over differing time courses from minutes to weeks. While the fundamental process occurs in the metabolic machinery of the cell, acute physiologic responses are essential in allowing the cells time to adjust.
Ventilatory acclimatization (increase in ventilation), requires approximately 4 days at a given altitude and is greatly enhanced by acetazolamide (Diamox). Patients with inadequate carotid body response or pulmonary or renal disease may have an insufficient ventilatory response and thus not adapt well to high altitude.
Circulatory changes occur that increase the delivery of oxygen to the tissues, leading to increased resting heart rate and mildly increased blood pressure. The blood circulation reacts to hypoxia with vasoconstriction, which improves ventilation/perfusion matching and gas exchange, but this increases the blood pressure and can lead to HAPE and right heart failure. Cerebral blood flow increases immediately on ascent to high altitude, returning toward normal over about a week. The magnitude of the increase varies but averages 24% at 3810m and more at higher altitude. Whether the headache of AMS is related to this flow increase is not known.
Hemoglobin concentration increases after ascent, increasing the oxygen-carrying capacity of the blood. Initially, it increases due to reduction in plasma volume and fluid shifts. Subsequently, over days to weeks, RBC production increases.
Sleep architecture is altered at high altitude, with frequent arousals and reports of disturbed sleep. This generally improves after several nights at a constant altitude, though periodic breathing remains common above 2700 m.
Frequency
The incidence of AMS varies depending on the rate of ascent and the maximum altitude reached. In moderate altitude (2000-3500m), the incidence ranges from 10-40%. Rapid ascent to approximately 4000m has been associated with incidences of 60-70%. Travelers flying to a high altitude destination at 3500-4000m can expect an AMS incidence of 25-35%. In those who hike above 4000m (and so ascend at a moderate pace), 25-50% will suffer from AMS. HACE is estimated to occur in about 1% or less of persons traveling above 4000m and in 1-3% of those with AMS.
Mortality/Morbidity
The natural history of AMS varies with altitude, ascent rate, and other factors. In general, the illness is self-limiting and symptoms improve slowly, with complete resolution in 1-3 days. However, with continued ascent, AMS is very likely to worsen and is more likely to progress to HACE. HACE may progress to stupor and coma over hours to days if untreated. The usual course is rapid, complete recovery if treatment is started promptly. Slower recovery results when treatment is delayed.
AMS occurs in non-acclimatized persons in the first 48 hours after ascent to altitudes above 2500 m, especially after rapid ascent (1 d or less). Symptoms usually begin a few hours after arrival at the new altitude but may arise as much as a day later, often after the first night's sleep. Headache is the principal symptom, typically frontal and throbbing. Gastrointestinal symptoms (anorexia, nausea, or vomiting), and constitutional symptoms (weakness, lightheadedness, or lassitude) are common. AMS is similar to an alcohol hangover, or to a nonspecific viral infection, but without fever.
Fluid retention is characteristic of AMS, and persons with AMS often report reduced urination. As AMS progresses, the headache worsens, and vomiting and increased lassitude develop. Altered level of consciousness herald the onset of clinical HACE.
The diagnosis of AMS requires headache plus at least one of the following symptoms: gastrointestinal (nausea, vomiting), constitutional (lightheadedness, dizziness, weakness, fatigue), or insomnia. Dehydration is commonly confused with AMS, as it can cause headache, weakness, nausea, and decreased urine output.
The most common history in HACE is a person ascending further despite symptoms of AMS; however, rarely, it may develop in the absence of AMS after a very rapid ascent or at extreme altitude in an apparently acclimatized person. Also, HACE commonly occurs in conjunction with HAPE.
Cure

(1) no further ascent until symptoms resolve,
(2) descend to a lower altitude if no improvement occurs with medical therapy, and
(3) at the first sign of HACE, descend immediately.
A small percentage (< 10%) of persons with AMS will go on to develop HACE, especially with continued ascent in the presence of AMS symptoms.
Descent to an altitude below that where symptoms started is always effective treatment but may not be practical or possible, accordingly, a descent of 500-1000m is usually sufficient.
Acetazolamide accelerates acclimatization and thus quickens resolution of the illness, but this may still require 12-24 hours; it is of limited value in HACE because of its relatively slow action. Acetazolamide can be taken episodically without fear of rebound symptoms when it is discontinued. Dexamethasone swiftly reverses symptoms (2-4 h) but does not improve acclimatization. It is the drug of choice for treating HACE and should be given early. Both agents may be used to treat AMS if the patient does not descend.
Oxygen is extremely effective, but availability is often limited. Portable hyperbaric chambers made of coated fabric are now widely available among adventure travel groups on expeditions and in high-altitude clinics. These are all lightweight, coated fabric bags about 2 m long and 0.7 m in diameter. The patient is placed completely within the bag, which is sealed shut and inflated with a manually operated pump, pressurizing the inside to 105-220 mm Hg above ambient atmospheric pressure. Depending on the elevation of use, a simulated descent of up to 2000 m may be achieved within minutes. Continuous pumping is necessary to flush CO2 out of the system, unless a chemical scrubber system is used. Patients are typically treated in 1-hour increments and then are reevaluated.
Importantly, in HACE cases, these chambers should only be used as a means of acute/temporizing care (eg, to improve a patient's ability to more safely participate in their evacuation in technical terrain). They should never be considered as a replacement for actual descent.
Alcohol and other respiratory depressants should be avoided in someone with AMS.

There is enough and more written on AMS in IM as well as on the web - this is a very useful article I found, which is highly summarised, but for those who like snippets:

1. AMS is prevalent but harmless but can turn into HACE or HAPE on continued ascent, which can be fatal. If one gets mild AMS, stop ascending and if it becomes ok, ascend again. If not immediately descend.
2. Its main cause is lack of oxygen at higher altitude and chances increase due to rapid ascent, lack of acclimitisation and illness (especially respiratory)
3. Symptoms include Headache, Nausea, Vomitting, lack of sleep, light headedness, weakness etc, but no fever. Water retention (lack of adequate urination) is another symptom and drinking lot of water and or any alcohol is a big no.
4. Altitude causes multiple responses in the body including higher ventialtion (respiration), increased blood pressure and heart rate, Haemoglobin increase, higher RBC production etc., which take between a few minutes to 1 week to take effect, thus staying at a particular altitude for 2-3 days allows only partial acclimitisation.
5. Prevention and cure include - Diamox (takes 24-48 hours to act), Dexamethasone (not preventive but quick cure, within 2-4 hours), oxygen cyclinder, pressurisation bag (heard for the first time) - which simulates descent, actual descent of 500-1000m or more.

Absolutely brilliant posts by Rajat. One of the best threads on IM. So many phenomenons of physics explained in such a lucid manner. It says the definitive word on all the possible arguments on the physics involved during a trek. Are you a physicist?

I would love to repost your content on my blog, with due acknowledgement and only if you permit.

makes sense and is very useful indeed! thanks a lot!

Not much input I can provide cos such scientific expertise is way beyond me! but I can definitely appreciate the effort and the information is very useful !

Thanks Rahul - I have just collated some interesting stuff and tried to apply it to trekking, no rocket science this (took me two whole months to get my hands around temperature determination model - so I am not that smart). I am not a physicist but interested in physics.

Sure - please go ahead and use the material, it is for anyone and everyone interested in this kind of stuff.

Saw your blog - nice treks, wish to do these some day. You may be intereested in the following post as well.

Trekking Places and Itineraries

Good effort here and some insightful nuggets. One can never do enough research before embarking on high altitude climbs and hikes.

Adiyogi

Thanks Adiyogi.

What water purification tables available in India ? Can any one please throw some idea.

Thanks

Dtaunk,

You can consider using 'Zero-B' clorine tabs. I use them extensively while on the trail.

Rajat

Doesnt the water taste funny after that? It will probably taste like water from the swimming pool...

Rajat, where can you get these tablets?

Well you will definitely get a taste like chlorine. But after a few sips, it becomes manageable. And it is definitely better than having 'bad stomach' when you are trekking.

I pick them up from medicine stores. Though not all stores will keep them.

Rajat