Figure 1. Clinically Derived Oxyhemoglobin Dissociation Curve and Variance of Oxyhemoglobin Saturation (Sao₂) Within Narrow Arterial Oxygen Tension (Pao₂) Increments.

A, Pao₂ and Sao₂ become increasingly variant as Pao₂ decreases. B, Within the actionable range of hypoxemia, Sao₂ correlates progressively less closely with Pao₂ as Pao₂ decreases. Note the increasingly broad ranges and SDs of Sao₂ within progressively decreasing increments of 5 mm Hg in Pao₂. ABGs indicates arterial blood gases.