Fig 3.

Probability of occult hypoxemia (arterial oxygen saturation SaO₂ <88% when pulse oximetry SpO₂ ≥92%) on second paired SpO₂-SaO₂ measurements, by race. Probability is based on the SpO₂-SaO₂ difference from a first pair of readings measured earlier that same day, race of the patient, and pulse oximetry reading at the time of measurement of the second pair of SpO₂-SaO₂ readings. Adjusted probabilities were calculated from a regression stratified by race, and presented using www.iconarray.com visualization recommendations. SpO₂-SaO₂ differences were divided into groups by tertiles from the first reading of the day; these groups ranged from having the lowest SpO₂-SaO₂ difference (SaO₂ 0.1 percentage points lower than or any amount higher than SpO₂) to having the largest SpO₂-SaO₂ difference (SaO₂2 at least 2.5 percentage points lower than SpO₂). Probabilities of occult hypoxemia on the second pair of SpO₂-SaO₂ readings depended on the magnitude of the difference on the first pair, and as a function of the SpO₂ at the second pair and the patient’s race