Which value is most representative of the partial pressure of oxygen in arterial blood?

The partial pressure of oxygen (PaO2) in arterial blood is an important measure that reflects how well oxygen is able to move from the lungs into the bloodstream. Under normal physiological conditions, the typical range of PaO2 in healthy adults breathing room air is approximately 75 to 100 mm Hg. A value around 85 mm Hg falls well within this normal range, indicating that the oxygenation of arterial blood is sufficient for the needs of the body's tissues. This level suggests effective gas exchange and adequate oxygen delivery.

Values like 40 mm Hg are indicative of hypoxemia and can signify inadequate oxygenation, while a PaO2 of 55 mm Hg or 70 mm Hg also suggests lower than normal oxygen levels, indicating possible respiratory impairment or a need for supplemental oxygen. Therefore, 85 mm Hg is the most representative of healthy arterial oxygen levels and reflects an optimal state of oxygenation.