What is AV-O2 (arteriovenous oxygen) difference and how is it abbreviated in medical literature?

Arteriovenous Oxygen Difference (AV-O2 Difference)

The arteriovenous oxygen difference (AV-O2 difference) represents the difference in oxygen content between arterial and mixed venous blood, and is most commonly abbreviated as C(a–v)O2 in medical literature. 1

Definition and Physiological Meaning

• C(a–v)O2 is the standard abbreviation, where "C" denotes content, "a" represents arterial blood, and "v" represents mixed venous blood 1

• This parameter quantifies the difference in oxygen content between arterial and mixed venous blood, expressed in milliliters of O2 per deciliter or liter of blood 1

• The AV-O2 difference reflects the amount of oxygen extracted by tissues from the blood as it passes through the systemic circulation 1

Alternative Abbreviations in Literature

• AVOD (arteriovenous oxygen difference) is used in some research contexts 2, 3

• avDO2 appears in European literature, particularly German publications 4

• aV˙O2 difference is used when discussing functional capacity and maximal oxygen uptake 1

• (a-v)O2 is an alternative notation seen in physiological research 2, 5

Clinical Significance and Application

• The C(a–v)O2 is a critical component of the Fick equation for calculating oxygen consumption: V˙O2max = (HR × SV) × aV˙O2 difference 1

• This parameter serves as an integrating indicator of oxygen availability and tissue oxygen consumption, making it valuable for assessing cardiovascular balance 4

• In critically ill patients, the arteriovenous O2 difference between 3-5 cc O2/100ml of blood is considered a more reliable parameter than mixed venous oxygen saturation (SvO2) alone, particularly in VA-ECMO patients 6

• The O2 pulse (oxygen uptake divided by heart rate) is numerically equal to the product of stroke volume and C(a–v)O2, making it useful for estimating stroke volume when C(a–v)O2 is assumed to be maximal and normal 1

Important Clinical Caveats

• C(a–v)O2 is the preferred and most standardized abbreviation according to major cardiopulmonary societies (ATS/ACCP and American Heart Association) 1

• When interpreting this parameter, recognize that it reflects both oxygen delivery and consumption, so changes can result from alterations in cardiac output, hemoglobin concentration, arterial oxygen saturation, or tissue metabolic demands 4

• The measurement requires simultaneous arterial and mixed venous (pulmonary artery) blood sampling for accurate determination 1