The Difference Between Hypoxemia and Tissue Hypoxia
Hypoxemia
Hypoxemia = low arterial oxygen tension (PaO2) that is associated with low oxygen saturation assessed by pulse oximetry (SpO2). Hypoxemia indicates inadequate oxygenation.
Hypoxemia
Hypoxemia is low arterial oxygen saturation (SpO2 <94%). In tissue hypoxemia, oxygen delivery is not adequate to meet tissue oxygen demand. Hypoxemia doesn’t always lead to tissue hypoxemia. Compensatory mechanisms can increase the oxygen-carrying capacity (e.g. increased Hgb conc.) or blood flow (e.g. increased cardiac output) to maintain tissue oxygenation despite hypoxemia.
“SpO2 <94% in a child who is breathing room air indicates hypoxemia” – PALS text