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IĆ36 800 Series Operator's Manual
aĆv Extraction Index
The a-v extraction index (ctO
2
([a-v]/a)) aids in the interpretation of the
arterial-venous oxygen content difference and can indicate inadequate oxygen
content in arterial blood or inadequate cardiac output to meet oxygen demands of
the tissues.
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The value is most properly determined using arterial blood and
mixed venous blood.
The system determines the a-v extraction index as follows:
ctO
2
([a–v]ńa) +
ctO
2
(a–v)
ctO
2
(a)
Oxygen Consumption Rate
The oxygen consumption rate (VO
2
), which is also referred to as “oxygen uptake”,
is a determination of the volume of oxygen consumed by the body per minute.
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The system determines the oxygen consumption rate as follows:
VO
2
= ctO
2
(a–v) × Qt × 10
Oxygen Delivery
Oxygen delivery (DO
2
), which is also referred to as “oxygen transport”, refers to
the volume of oxygen per minute that is transported to the tissues.
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The system determines oxygen delivery as follows:
DO
2
= ctO
2
(a) × Qt × 10
Physiologic Shunt
The physiologic shunt [Qsp/Qt(T)] is that portion of the cardiac output entering the
left side of the heart that does not perfectly respire with the alveoli. The shunt
calculation represents the best available means of delineating the extent to which
the pulmonary system contributes to hypoximia.
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