Arterial Blood Gases Terminology Clinical Chemistry Review 124
TERM EXPLANATION
Hypoxemia Low O 2 content in arterial blood
Hypoxia Lack of O 2 at cellular level
Partial pressure Barometric pressure × % gas concentration
PCO 2 Partial pressure of CO 2 expressed in mm of Hg. Directly related to amount of dissolved CO 2. Measure
of respiratory component (inversely proportional to respiration)
PO 2 Partial pressure of O 2. Assesses pulmonary function
Oxygen dissociation curve Graph showing relationship between oxygen saturation & PO 2. Provides information about
hemoglobin’s affinity for O 2
2,3-Diphosphoglycerate Phosphate compound in RBCs that affects O 2 dissociation curve. Low levels inhibit release of O 2 to
(2,3-DPG) tissues
Oxygen saturation Amount of O 2 that iscombined with hemoglobin, expressed as % of amount of O 2 that can be
combined with hemoglobin. 1 g of hemoglobin can combine with 1.34 mL of O 2
P 50 Partial pressure of O 2 at which hemoglobin oxygen saturation is 50%. Low value = ↑oxygen
affinity (shift to the left in O 2 dissociation curve). High value = ↓oxygen affinity (shift to right)
