Terminology:
Partial Pressure of oxygen dissolved in arterial blood is termed
PaO2.
Percent saturation of oxygen bound to hemoglobin in arterial
blood is termed SaO2.
When measured by a pulse oximeter, SaO2 is termed SpO2.
PaO2, the oxygen that is dissolved in plasma is the driving
pressure that forces oxygen to combine with hemoglobin.
Hypoxemia is a below-normal level of oxygen in your blood,
specifically in the arteries. Hypoxemia is a sign of a problem
related to breathing or circulation, and may result in various
symptoms, such as shortness of breath.
Physiology:
When oxygen demand increases, heart rate and cardiac output
increases, which increases the flow of blood through the lung
and the pressure required to force blood through the arterioles
and capillaries of the lung. This is evident through a physical
activity. Also a decrease in O2 saturation also forces the heart
to increase its activity to compensate with the decrease of
oxygen level.
