In managing suspected hypoxia in a conscious passenger, which oxygen delivery method is considered standard?

• A. Tight-fitting mask delivering 100% oxygen
• B. Nasal cannula
• C. Simple face mask
• D. Ambient air

Answer: (A)

When hypoxia is suspected, the goal is to deliver the highest and most reliable oxygen concentration to quickly reverse low oxygen levels. A tight-fitting mask delivering 100% oxygen is the standard because it minimizes air entrainment and, with a reservoir, provides near-full oxygen concentration with a high flow rate (about 15 L/min). This maximizes the oxygen actually reaching the lungs during each breath, which is crucial for a conscious passenger who may deteriorate if hypoxia isn’t rapidly corrected.

Nasal cannula, by contrast, delivers a much lower and variable fraction of inspired oxygen and depends on the person’s breathing pattern, making it insufficient in a hypoxic situation. A simple face mask without a reservoir also yields less reliable oxygen delivery and generally not 100% O2. Ambient air provides no added oxygen, so it’s not appropriate when hypoxia is suspected. Monitor the passenger’s oxygen saturation and symptoms closely and be prepared to escalate if needed.