The problems posed by exercise at high altitude for oxygen diffusion across the blood-gas barrier have been recognized since the early part of this century. But the successful ascent of Mt. Everest (altitude 8848 m) by two climbers without supplementary oxygen in 1978 focused attention on this issue. We have therefore carried out a theoretical study of gas exchange under these conditions of extreme hypoxia. Calculations of oxygenation along the pulmonary capillaries show that, even at rest, there is an alveolar-end capillary PO2 of about 6 torr caused by diffusion limitation, and this widens rapidly on mild exercise. As the oxygen uptake is increased, the PO2 of mixed venous blood falls to very low values. If we assume a minimal value of 15 torr, a maximal oxygen uptake on the summit of less than 700 ml/min is predicted. VO2max is extremely sensitive to barometric pressure, and to a lesser extent to lung diffusing capacity.
自本世纪初以来，人们就已经认识到在高海拔地区运动给氧气穿过气血屏障带来的问题。但是1978年两名登山者在没有补充氧气的情况下成功登顶珠穆朗玛峰（海拔8848米），使得这个问题受到关注。因此，我们对极端低氧条件下的气体交换进行了理论研究。沿肺毛细血管的氧合计算表明，即使在静息状态下，由于扩散限制，肺泡末端毛细血管的氧分压约为6托，在轻度运动时这一数值会迅速增大。随着摄氧量增加，混合静脉血的氧分压会降至非常低的值。如果我们假设最低值为15托，那么预计在山顶的最大摄氧量小于700毫升/分钟。最大摄氧量对气压极其敏感，对肺扩散能力的敏感性则稍低。
