Further to my last blog on this subject, in regard to the use of dispersible aspirin or any other medication likely to promote blood-thinning: all these can be contra-indicated if the climber is already on anti-clotting agents (like Warfarin) or is taking medications for circulatory illness such as diabetes. This is not to say they cannot be used, but your doctor or, better still, a pharmacist should be consulted first to ensure your prescription pills are compatible.
Many thanks to those of you who made excellent comments over the blog and by email with their own experiences of altitude illness. A common thread amongst them was the rapid ascent from valley base (1000m or less) to overnighting in bivvies and huts at 3000m-plus, having come from homes close to sea-level. Many had arrived in the Alps having undergone tough and effective fitness programmes and having made successful day ascents of 3000m peaks without any ill-effects in the previous weeks, yet still suffered serious ill-effects when overnighting above 3000m.
Rapid ascent seems for the most part to be the critical factor inducing altitude illness in those prone to it. There is more than anecdotal evidence to suggest the efficacy of a limited daily ascent height of 400m per day to aid acclimatisation. Work done by Huber and Pilcher of Switzerland (see last blog) indicates this, and its use by alpine-style ascenders in recent years in the Himalayas has resulted in 80% summit successes in those groups ascending together with all their tents and equipment, with each member helping with tent rigging and cooking, as against the exhausting "climb high, sleep low" seige tactics of many larger groups on 8000ers.
I have where possible used this mid-way bivvy tactic on 4000-plus peaks for many years with great success in summer conditions. The advantages of overnight rest, rehydration, and nutritional intake when not overstretched and exhausted are obvious. The body has time to recover from exertion at altitude and is thus able to more efficiently metabolise foods and liquids, giving one the best possible conditioning for the next day's summit push and descent. When you are descending by the same route, excess gear can be left at the bivvy and picked up on the way down. I use a pack-liner for this, which is identity-marked, and this saves a lot of pain (see pic).
Now some will say, "Well, that's what the huts are there for!" But they are not always around when you need them, especially in the more isolated alpine areas, or on infrequently-climbed routes. There is a strong link with general exhaustion and altitude sickness, and the independence of being able to establish a good summer overnight bivvy helps to overcome this problem.
ELECTROLYTE REPLACEMENT -- For a long time it was thought that a high-electrolyte (salts) intake in the form of flavoured drinks helped to stave off heat exhaustion/stroke at altitude. Actually, all that happens is that over-salted, over-sweetened drinks taken when tired induce nausea, loss of appetite and, overall, energy. This results in an increased chance of altitude sickness through adverse effects on blood chemistry. Electrolytes are best absorbed in hot meals, at rest, when the body has time to metabolise them. Most good ration packs these days have more than enough of all the chemicals your body needs to sustain a good blood-chemistry balance for 12-18 hours of work. (More about nutrition another time).
The higher you go, the more body fluids you lose (experienced climbers don't need me to explain this!). The more fluid you lose, the thicker your blood becomes, again increasing your chance of altitude sickness. This is where carrying a bladder and drinking-tube really helps, enabling you to drink frequently while on the move. Don't flavour your water, chew raisins or other soft dried fruits between drinks. This way, you rehydrate, take on energy and refresh a dry mouth. Avoid eating nuts and biscuits while on the move, their dryness can bring on choking and coughing fits. The same goes for large cereal bars. One should eat them only when stationary. Chewing large mouthfuls of anything dry whilst trying to climb at altitude is going to end up choking you.
(In the next blog on this subject we will discuss "CUMULATIVE CONDITIONING ASCENTS" over time.Age and Fitness factors).