At what SaO2 level is oxygen therapy generally considered necessary?

Oxygen therapy is generally considered necessary when the arterial oxygen saturation (SaO2) level falls below 90%. This threshold is significant because maintaining an SaO2 level of at least 90% is crucial to ensure adequate tissue oxygenation and prevent hypoxia, which can lead to serious physiological complications. When the SaO2 drops into the range of 87-90%, patients may begin to show signs of respiratory distress, and supplemental oxygen is typically indicated to help improve their saturation levels and enhance overall oxygen delivery to tissues.

The specified range of 87-90% marks a critical point where intervention is warranted to prevent further decline in oxygen levels. Therefore, the choice that indicates this range aligns with standard clinical practice in respiratory care, making it the appropriate answer for when oxygen therapy is generally initiated.