Figure 2. Relationship Between Changes in Oxyhemoglobin Saturation (Sao₂) and Changes in Arterial Oxygen Tension (Pao₂) in Serial Arterial Blood Gases (ABGs).

A, The relationship between changes in Sao₂ and Pao₂ on sequential ABGs are shown, stratified by the lowest Pao₂ of the pair. Slopes of linear regression lines (m) increase with increasing hypoxemia (P < .001). The lines indicate linear regression ±95% CI. B, The frequency of opposite changes in Pao₂ and Sao₂ was stratified by degree of hypoxemia.