Advanced Hemodynamics - Orlando Health

Advanced Hemodynamic Monitoring
Oxygen Consumption
Oxygen demand is the amount of oxygen the tissues require for metabolism. This demand is
influenced by several factors such as metabolic rate, muscular work and temperature. As long as the
oxygen demand does not exceed the oxygen delivery, homeostasis will be maintained. If the
delivery does not match the demand, the body will use alternative sources besides oxygen to
generate energy such as fat and proteins. This will result in anaerobe metabolism and lactate
acidosis.
Oxygen consumption (VO 2 I) can be measured by subtracting the volume of O 2 (arterial
oxygen content) leaving the heart from the volume of O 2 (venous oxygen content) returning to the
heart or [(CO/BSA x CaO 2 ) – (CO/BSA x CvO 2 )] x 10 dL/L = VO 2 I.
Under normal conditions oxygen consumption is 25%. However, during stress response the tissues
are capable of extracting 80% of oxygen. This is indicated by an increase in VO 2 I. Adequate
delivery is paramount in order to balance oxygen supply and demand and prevent anaerobe
metabolism. The normal range for VO 2 I is 120 – 160 ml/min/m 2 .
Certain conditions cause an increase in oxygen consumption. The following table provides
an overview of these conditions.
Condition
Percentage increase in VO 2 I
Fever
10% with every > 1C
Work of breathing 40%
Severe Infection 60%
Shivering 50 – 100%
Burns 100%
Endotracheal suctioning 27%
Chest trauma 60%
MODS 20 - 80%
Sepsis 50 – 100%
Head injury, sedated 89%
Head injury, unsedated 138%
Bath 23%
Position change 31%
Agitation 18%
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