NOTES By T. HOWARD SOMERVELL on ACCLIMATISATION AT HIGH ALTITUDES COLOUR IN TIBET TIBETAN CULTURE ------------------------------------------------------------------------ CHAPTER XII ACCLIMATISATION AT HIGH ALTITUDES The Everest Expedition of 1922 had no preconceived programme of scientific investigation, and was first and foremost an attempt to get up the mountain; though, as I had been connected with physiological research for some years, I was naturally anxious to make observations on the effect of altitude on the human frame. These observations were rather subjective, and were unaccompanied by any accurate data—in other words, the reader will be relieved to hear that there are no tables of figures to be reproduced. Barcroft and others were in the course of their Expedition to the Andes, and I knew full well their results would supply more accurate information on the exact process of acclimatisation at high altitudes than anything we could do with our simpler apparatus. We left it to this other Expedition, therefore, to supply the figures, while our observations were exclusively on the practical side; that is to say, we observed the rapidity and effect of acclimatisation, while not investigating exactly how it is brought about. The first effect of altitude, in such moderate degree as we encountered it on the plains of Tibet, was almost entirely a mere breathlessness, which limited our rate of walking, and increased the popularity of our uncomfortable Tibetan saddles when travelling uphill. A few of us had severe headaches from time to time; at the modest height of 17,000 feet I noticed Cheyne-Stokes respiration at night when lying down, though never when sitting or standing; and I remember being distinctly amused at the fact that one was unable to control it.[7] A few of the party had a single attack of vomiting, but no permanent effect was noticed, and by the time we had lived on the Tibetan Plateau for a few weeks we had lost all ill effects save only breathlessness, which, of course, persisted to some extent until we reached comparatively low elevations. Further effect at these heights was not noticed save in the case of some of the older members of the party, who suffered from a considerable loss of appetite while at the Base Camp at 16,000 feet; this effect on appetite did not improve as time went on. Footnote 7: For the benefit of the non-medical reader, Cheyne-Stokes breathing is the gradual alternation of shallow and deep respirations: usually about ten shallow breaths are followed by respirations which get gradually deeper; then by three or four really deep ones, which become shallower until the cycle recommences.