“…Cardiac failure and abnormalities may produce very similar end results. It is generally recognized in adults that there is rarely, if ever, any reduction in oxygen consumption when the pressure of oxygen in the ambient air falls, even to the low levels met with at very high altitudes (Barcroft, Elliott, Fraser, Herkel, Matthews and Talaat, 1934;Houston and Riley, 1947;Rothschuh, 1947;Frank and Wezler, 1948;Pugh, 1957). The oxygen tension falls in the arterial blood, but a sustained increase in respiration and alveolar ventilation helps to maintain the supply of oxygen to the tissues.…”