Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1106 page)

   Values are slightly lower in supine position.

   Difference between arterial blood and venous blood varies considerably, depending on the skin temperature, length of stasis, and muscular activity.

PARTIAL PRESSURE OF OXYGEN (pO
₂
),
BLOOD

   Definition

   The partial pressure of oxygen (pO
₂
) is a measure of the tension or pressure of oxygen dissolved in the blood. The pO
₂
of arterial blood is primarily related to the ability of the lungs to oxygenate blood from alveolar air.

   
Normal range:

   Arterial: >80–95 mm Hg (see Table 16.64)

   Venous: 35–40 mm Hg

TABLE 16–64. Arterial pO
₂

   Use

   To evaluate patients with pulmonary or acid–base disturbances

   To monitor patients with carbon monoxide poisoning, methemoglobinemia, or hemoglobin variant for O
₂
saturation

   To manage patients on mechanical respirators

   Prior to thoracic or general surgery