Coming down for air...AMS (Manali-Leh)... you better acclimatize!

My reasoning behind the comment on worse AMS score with a tunnel was something like this : the one good thing with the first part of the road is the very fact that you are exposed to a rapid ascent , more rapid than you can adjust fully to.

Hypoxia (i.e. low oxygen levels in the blood ) is what triggers acclimatisation response , to get the best/fastest reaction you need to have a significant drop.

These reaction start to play out in a relatively narrow range :

at 1500 meters you have zero acclimatisation response (but measurably lower work capacity) , in sitting position at 2500 meters there is some response to the situation , but no serious drop in oxygen levels - this is after all what you experience in a commercial flight.

A lot happens between 2500 and 3500 meters sleeping altitude : I´ve slept in Kalpa at 2800 a couple of times for example , and few seem to experience more than a little stress here. Most will have spent some nights in Shimla at 2200 before that.

The reactions to arriving in Leh vary , but is mostly consistent with the number of nights spent at intermediate elevations. There is a striking difference is what I´ve seen on the between Manali and Leh and the Srinagar-Leh road and this year in Spiti. Nights (because of the drop in oxygen saturation that comes from lying down) and really high passes in the daytime will push the body - when it works out well to speed the acclimatisation process , when pushed too hard over the breaking point.

Defining that precise breaking point is something that eludes the experts in the field , but there is some consensus that you can tolerate really fast ascents to 4000 meters provided if , as I´m fond of saying , you throw them down immediately : this is what skydivers do , but pilots are not allowed to fly in unpressurised aircrafts at this altitude for more than than thirty minutes. Again , these are people who are awake and not lying down. Truckers tend to stay in their vehicles , which most of the time also means sitting up , this would work in their favor when forced to night stops at high elevations.

It would be a nice thing to be able to present an exact answer , (or the gadgety approach , something similar to the computers worn by divers ), but when you read what the experts in the field have to say you realise this won´t happen any time soon. The condition is well known , it can be fairly accurately predicted ... there is an enormous body of evidence on why it happens , which tends to hide the embarrassing fact that we still don´t know how it happens. There are factors that are hidden to us , there are unique aspects to altitude sickness which don´t happen when people go hypoxic for other reasons , at lower altitudes.

vistet ! you described very well. As soon as oxygen level decreases..there are various stimulations.

1. Brain needs 20% of oxygen to work- so it makes you feel that you should breath deep and more. This is when you first feel brunt of altitude which can come with slight headache. Degree of headache depends on how your body has responded to given situation. For example: Somone who is having good vital capacity [ Pro. porters, high altitude residents or good athletic people ] will be having slight expension of lungs and this will be enough for brain to handle missing supply of oxygen. BUT tourist and normal people may feel sudden headache or vomitting as body fails to react fast to supply required oxygen. This is complex drama...as many sub factors are also there with both type of bodies. Blood pressure, Condition of lungs and heart also plays important role.

2. Second organ which comes under pressure is HEART itself. It needs good portion oxygen to work itself. Heart muscles expands under pressure- to get more blood in PUMP. This is why if you come from a expedition and get a x-ray done...you will be shocked to see size of your heart !

Now, coming to tunnel and how human body will go through it's effect..is somewhat subjective as AMS has no hardlines to follow.
I think that tunnel will give some easy gradient and people will feel fine by the time they reach TANDI as upto DARCHA- it is fine but first feel of altitude is felt on baralacha-la.

[ Staying in high altitude stimulates BONE MARROW to produce more RBC's - this process helps body to have maximum population of RBC's to carry every minute ratio of oxygen being inhaled by lungs...I think tunnel will help pressure on lungs ! ]

The main problem when we leave low altitudes is how breathing is normally regulated.The brain senses oxygen levels, carbon dioxide and acid balance in the blood- and unfortunately breathing is regulated primarily by the last two factors. Hypoxia stimulates to deeper breathing , but this reaction is immediately limited the moment it starts to change the acid balance. Episodes of hypoxia will stimulate the body to change in to another way of regulating breathing , that depends mainly on the oxygen levels in the blood.
A large vital capacity will not be accessible until this shift has occurred , and a professional athlete for example can easily find him/herself at a disadvantage compared to a overweight truck driver with recent time at high altitude.
Generally this change seems to take place somewhere around second or third night at 3000+. In principal terms shortcutting under the Rothang La should mean eliminating a tolerable episode of hypoxia , and poorer acclimatisation as a result from that.

The mechanism comes in to play as we hit the Manali-Leh road , but the profit from it comes after arriving in Leh for most people : the production time of red blood cells is minimum four to five days.Blood cell count do get elevated , but this is basically by cheating : same number of red blood cells in smaller volume of blood after increased urine output.

marginal i would say.

Its the resting altitude that matters. The famous adage- climb high and sleep low.

If the differnce is 700 mtrs. theoritically speaking they should acclimatise....but in this context 700 or 1000 ...would really mean the same.
Thus whether you take a long winded road that goes all the up and down to 700 mtrs net gain or you had that short cut through the tunnel...would essentially mean the sme...when it comes to sleeping and breathing the next night

I disagree with the above , both on the principles and the maths involved .

The main point about "climb high , sleep low" involves ... well , going high. The difference of travelling at the tunnel elevation after Manali compared to going up to the pass is a lot more than a 50 % higher max elevation . A tunnel will mean travelling faster around the 3000 meter mark , and arriving at that level (Keylong 3200-ish) or slightly higher (Jispa & Darcha, 3400 ): climb slow, sleep high.

If you look at an elevation curve over the roads to Leh


then every high point on the curve could be matched to a corresponding curve going down , representing the oxygen content in the blood. This will give a better view of the stress created in the system , keeping in mind that the response is not proportional . It´s not just the isolated low values/max elevations that are interesting , but the time spent there. Looking at the area and not just the curve would be more relevant. Thus the long winding road means longer time at a higher mean elevation , meaning more stress, meaning more efficient acclimatisation.

I do agree that greater exposure to higher altitudes during the day for the given same sleeping altitude is better for acclimatisation in terms of body readiness for more altitude challenge ahead.

My cmment was purely a comparison for a day's effect on taking these 2 different routes. From a Manali-Leh drive standpoint, obviously greater exposure to altitude during day and comfortable sleeping altitude at night would be the prefered way.

I dont think there is anything as greater than 50% max altitude...50% of what? One generally comes down few hundred mtrs from the humanely possible high point in a days trek or climb so that net gain in sleeping altitude isnt too stark. 1000-1500 mtrs in a days climb is max one would generally expect. Obviously the case of pilots in non-pressurised aircraft is different.

The altitude profile graph...whts on the X axis and altitude gradient of which area? Manali- Keylong? The 4000er spike would be Rohtang?

The x axis is distance , and the grey area is the Srinagar-Leh road( it´s posted here in the gallery under "the roads to Leh") . Obviously when thinking of altitude the relevant axis should be time and not distance , but then you would need to make more or less one curve for every kind of vehicle , different night stops etc.

The percentages were about the altitude difference between tunnel vs the Rothang , no attempt to fix human capabilities.

The pilot comparison is interesting , I remember browsing the US FAA standards ,which says that pilots are allowed max thirty minutes at 4000 meters without oxygen -which for example gives room for taking up skydivers in non-pressurised air crafts .

I do not know if this is the right way. I want guidence so I am posting here.

I plan to visit leh this may. Am 62 and could not climb further than Gorakhshep on the way to everest base in 2003 (i.e. when I was 57.
Will some one tell me if i can stop on my journey from manali to leh? that is, if i travel by bus, is it possible to find a seat for the onward journey to leh?(It is OK if i have pay the full ticket from manali to leh, every time i board a bus)
which are the places where i should stop?

bmp rao.

If I'm not mistaken I read in IM that HRTC's bus does an overnight halt at Keylang.
In any case it won't be a problem to get an onward ticket if you do it in stages. You don't have to buy full-way every time. Plenty of people start at Keylang. In fact HRTC's timetable lists 2 daily buses originating at Keylang. You may like to have a look:
http://himachal.nic.in/hrtc/route.asp

I did Manali to Keylong , stayed the next day in Keylong , and went on the next day . Getting a ticket involved a complex set of rules and linguistic skills ( stepping out in to the road , arching one eyebrow and saying "Leh ?") . I tried the buying a ticket in advance , which landed me in the amchis consultation room , and almost made me wish being sick to see the treatment.

Keylong is the place with most amenities , but there are more options , all around the three thousand meter mark : I´ve always wanted to jump off at Sissu, the first nice village with a Lahauli "Tibetan" feel.There is at least a PWD rest house. Koksar , or what you notice of it from the road and a short stop is more like a Army truck stop.

With the HRTC buses ( nice link , thanx ) I don´t worry , ask around when it will come around , sit down in the chai shop or on my pack by the roadside. The bus will come , sooner or later , or something else will turn up before that. The high end buses and jeeps will more likely be crammed full with people going all the way to Leh , esp. just after the road has opened , I guess - I´ve mainly been in Ladakh at the tail end of the season.

The most important thing in acclimatization for the road is to at least get a night each at 2000+ , and one around three thousand. Manali just barely fits the bill for the first night (altitude 2050) , you can tweak this by taking a day trip up to the Rothang , or better still sleep in Solang , 2500-ish instead.

All your options after the Rothang and up to Darcha are between 3100 to 3400 : if you put in two nights totally at this altitude you will probably have made the the important basic shift in breathing regulation that allows you to deal with high altitude a lot better.

Between Darcha and Upshi , fifty klicks from Leh , you have no practical solutions that are within safe ascent guide lines : Sarchu is at 4253 , Pang 4500. Even locals who go directly from Keylong to Sarchu and stay there may have problems dealing with this. The second night at three thousand means in no way full acclimatization to that altitude , but it will help reducing the consequences if you get snagged on the high sections - something I´ve experienced twice.

Lastly , the age issue : I wouldn´t worry over it . There has been made for example a fairly large study at the Thorung La in Nepal and it showed the opposite of what people expected : in statistical terms the older fared better than the younger . This suggests to me that behaviour and prior experience often will outweigh being at peak physical condition.

For normal healthy people it is generally OK to spend a night below 4000 metres. It will not cause serious symptoms of AMS, though it might be difficult to fall asleep. Above 4000 metres AMS becomes more likely. We had a dreadful night in Sarchu coming from Manali.

Of course what you do is also significant. Trekking, carrying a load, will increase the strain, and the danger, can´t really be compared to riding a bus or a jeep.

There is a large study made on the people who flew up to Everest Hotel : they were given Diamox on arriving , had access to oxygen ..and around 15 % spent their whole time in bed , until they flew down. This at an altitude slightly higher than Lhasa : 3800

Serious or not , certainly incapacitating. And it does happen at a lot lower elevations than we often think : last year I met a couple in Tabo(3265) who had made the strategic mistake of not sleeping in Kalpa at 2800 , and she was out of commission, in bed , the whole day.

If you look around a bit here you can for example find the travelogue that mentions (firsthand ) driving up to Keylong, and vomiting there. The principle is true , but I wouldn´t take it far.

Yes, it can certainly be bad even on the road, especially as there is really no easy way down or out between Baralacha La and Taglang La. One of my friends went by taxi from Keylong, and the driver got so sick that he had to drive the car across Taglang La.

Going up to Leh I think most tourists feel really miserable. We certainly did part of the way when we went by bus, even though we had spent several nights in Manali. A way to avoid it would be to break the journey in Keylong, or coming in via Spiti. However, then, one might have to go with slower and less comfortable buses.

It is all about spending time on altitude. The problem is that most tourists are short of time.

AMS symptoms may certainly come on lower altitudes than 4000 meters. It really depends on how fast the ascent has been. We went from sea level to 3200 (by cable car), in one day, slept on 3200, and had severe head ache and insomnia. Nevertheless, it was not worse than that we could scale a 4100 m peak the next day.

For most people it is rarely dangerous under 4000 meters, and most often on elevations lower than 4000 the symptoms disappears after a days rest.

The problem with Manali is that it lies just at the threshold for acclimatization : my guess here is that some start to acclimatize (slowly) and others ...don´t. The only part (according to my gps last year) that lives up to 2000+ is Vashisht , the town is around 200 meters lower. The tweak section for Manali-Leh you´ll find here

Yes, and a lot of tourists are impatient to get ahead, as they are short of time, not sit around in Manali. Last time we went we had no problems as we were cycling, in fact our friends who went by jeep had more epics.

Next time we will consider flying in to Leh. From what I understand there are a lot more flights than when we were in Ladakh. At that time the flights were extremeley erratic, and one could get bumbed at any time.