Cardiopulmonary functional changes in acute acclimatisation to high altitude in mountaineers.

Simple cardiopulmonary functions were studied serially in 26 mountaineers between sea level and an altitude of 25,200 ft. Up to 12,000 ft there was no altitude sickness, though there were complaints of leech bite (26.9%) and blisters (3.8%). One member died of exhaustion, two developed pulmonary oedema, one "flu" (at 15,600 ft) and one pleural rub (at 21,000 ft). Up to 16,000 ft altitude, 4 to 7.7% developed diarrhoea or epistaxis only, but at higher levels 25 to 50% subjects developed several symptoms, besides excessive dyspnea. These included diarrhoea (35-60%), vomiting (30%) abdominal pain (35-60%), rectal bleeding (15%), chest pain (10-40%), dry cough (40-60%), giddiness (30%) and poor memory (7.7%). A small rise in blood pressure was seen (for systolic at lower and diastolic at greater altitudes). After 18,200 ft the steady increase seen in VE slowed and the rise in heart rate and respiratory rate (f) became steeper. After a small rise at 7,800 ft, FVC and FEV1 showed a gradual decline at higher altitudes. After a large initial increase in PEFR up to 12,000 ft, a gradual decline was seen. The mean weight loss during the expedition was 8 +/- 2.7 kg. These changes seem to be due to an incomplete acclimatisation, which future mountaineering teams should take into consideration to avoid health problems and improve performance.