Factors affecting PvO2

Basic, Physiology

Normal mixed venous oxygen tension (PvO2) is approximately 40 mmHg, representing the balance between oxygen consumption and oxygen delivery. A true PvO2 measurement must come from a mixed venous blood sample containing venous drainage from the SVC, IVC, and the heart. Thus, the sample should be obtained from a pulmonary artery catheter. There are several factors that determine PvO2, which can be remembered using the mnemonic COALS:

  1. Cardiac output
  2. Oxygen consumption
  3. Amount of hemoglobin
  4. Loading of hemoglobin
  5. Saturation of hemoglobin

Of note, PvO2 can be used in lieu of SvO2 (mixed venous oxygen saturation), which is normally 65-75%.

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Answered correctly

2015

Year asked

Author
Lindsay Regali, MD