Acclimatization

Towards Aconcagua's Summit, with Paolo. (Jan,2005)

If I were to rank the reasons why people don’t summit, or reach their trek objective, I’d rank poor acclimatization as number1.  Bad weather (leading to lost of time) would be second only.

One should give proper focus and attention in his/her acclimatization program for a trip, be it during, or right before (1-2 weeks) the main trip.  Or risk failing.

Here are some tid-bits on this topic to help out those that are new in high altitude trekking or climbing.

 AMS, HAPE and HACE

Acute Mountain Sickness (AMS) is a temporary sickness (hence acute) when in a high altitude environment (maybe felt from as low as 9000ft or even lower for some); characterized by headache, lack of appetite, nausea, vomiting, headache.  Mild AMS in the mountain is NORMAL.  I’d say that in 50% or more of my past climbs, I’ve got AMS in varying severity, though mostly mild.  Expect to get headache, breathlessness (may or may not be related to AMS), fast heartbeat while resting, occasional vomiting, or lost of appetite.  Just fight it, take  medications, drink lots of fluids (3li), follow proper acclimatization technique described below.  

If left unchecked, especially if the climber ignored the symptoms of AMS and went for a higher altitude,  this could progress to High Altitude Cerebral Edema (HACE) or High Altitude Pulmonary Edema (HAPE), severe forms of AMS.  When the body failed to adapt to thin air or lack of oxygen, excessive fluid build-up in the lungs or skull may happen.  Excessive fluid in the lungs can ‘drown’ the sick.  Fluid in the skull disrupts thinking and balance and leads to accidents.  One form of edema leads to the next – i.e. if one has HAPE, expect him/her to get HACE soon.

One of my teammates in Vinson (Antarctica) developed HAPE and the symptoms were bad coughing with ‘gurgling sound’ in the chest.  He was unable to sleep during the night as fluid interrupts his breathing.  He was later evacuated, the only cure for this is to go down.

Low Lander by Design

Sudden exposure to thin air is dangerous. Say, if one flew straight to the summit of Everest, he/she would collapse in a few minutes and die few more minutes later because the body doesn’t have the capacity to instantly absorb sufficient oxygen to survive. The year before I climbed Cho Oyu, I read about an Italian climber who zoomed fast to Camp 1 of Cho Oyu on the fifth day of his arrival in Kathmandu. It took me 12 days to reach that camp, and  I got sick despite the length and slowness of my climb. The Italian died on his sixth day.

Proper Acclimatization

Proper acclimatization reduced the chance of getting AMS. By spending time at a higher altitude coupled with recovery time at a lower altitude, the body adjusts to thin air by producing more red blood cells to maximize oxygen gathering during breathing. This is a slow process, and most climbers followed a simple rule. In Swahili it was: “Pole, pole,” meaning,  “Slowly, slowly.” The faster you go up, the higher the risk of AMS. 

“Climb High, Sleep Low”. Normally, at high altitudes a climber must reach a significant altitude say, 300-600 meters. This will fool the body as the climber breathed thinner air up, then return down to sleep with relatively thicker air. This hastened acclimatization and helped avoid AMS and edema.

Spacing and Rest.  A guideline in high-altitude mountaineering is to space the camp at 300-vertical meters to allow for better physiological adaptation.   Then every 3 days of climbing, rest for 1 day to recover and adjust.  Sometimes, this guideline is not feasible due to terrain limitation so extra precaution or alternative technique should be considered.  In Cho Oyu,  we were unable to follow most of these guidelines due to many reasons.  Maybe that’s partly the reason why one of my teammates got sick, and his frost-nips and its associated pain lasted to a year.

Survival and Performance

Acclimatization has two components. The first is to adapt to the changing atmospheric pressure so you don’t get AMS’d, especially its advanced form of edema which could lead to death. 

The second component is to acclimatize enough to improve PERFORMANCE (increase the oxygen level, normalize the BP, have a near normal heartbeat). You may not feel sick, but your body could still be getting weaker as the altitude increases. That affects your climb performance and chance of summit success. You have to acclimatize more than just to preserve your health. 

Limitation and use of O2

When one reach the death zone, at around 26,000ft/ 8000m,  the air pressure (and hence O2 level) is down to almost 1/3.  In this condition, the body is unable to further acclimatize.  Yes, sayonara!

But there’s hope.  Supplemental O2 can be used when one is in the death zone.  We also use this either right before the death zone (ex. Camp3 of Everest during the night sleep or on the way to Camp4 –which is in the death zone) to reduce the chance of fast degradation.  On the way down, one may still use O2 for RECOVERY.  Yes, just to finish up the remaining O2 in the bottle.  Sayang eh. 

So the next time (or the first time) that you're in a high-altitude environment, remember - TAKE IT SLOWLY!   :)

 

Related posts:

Supplemental Oxygen Use

Medicines and Supplements (mentioned the use of AMS-relevant drug called Diamox)

High-Altitude Training