Supplemental oxygen is indicated when?

• A. Fever is present
• B. Hypoxia is suspected
• C. During exercise is performed
• D. During sleep

Answer: (B)

Supplemental oxygen is used to prevent tissue hypoxia when oxygen delivery to the blood is compromised. The best cue for starting oxygen is suspected hypoxia—if there are signs or measurements suggesting low oxygen in the blood, providing supplemental oxygen helps raise the arterial oxygen content and SpO2 while you confirm the extent of hypoxemia with monitoring.

In practice, you’d start oxygen when you suspect hypoxia based on objective data (low SpO2 or low PaO2) or clinical signs such as increased work of breathing, cyanosis, confusion, or restlessness. A fever by itself doesn’t trigger oxygen therapy, since it isn’t an indicator of low blood oxygen. Oxygen may be used during exercise or sleep in patients who desaturate during those states, but that’s specific to the patient’s oxygenation status, not a blanket indication. After initiating therapy, continuous monitoring with pulse oximetry and arterial blood gases helps maintain the appropriate target range for oxygenation.