Oxygen saturation levels in the well elderly: altitude makes a difference.

1. A reduction in oxygenation indicated by a lower PO2 and O2 saturation is a normal part of aging, but a change in carbon dioxide level is considered to reflect pulmonary disease. 2. The oxygen saturations of the well elderly living at moderate altitude and those living at low altitude were at the lower limits of normal for their respective altitudes. 3. Well elderly living at moderate altitude had an oxygen saturation that was significantly lower than the oxygen saturation of the people living at sea level. 4. Because of the wide range of oxygen saturation levels that exist in normal individuals, it is important to evaluate changes in oxygen saturation against the person's own level.