What is the primary risk if a nonrebreather mask's one-way valve is stuck closed?

• A. Hypoxemia due to reduced inspiratory oxygen
• B. CO2 rebreathing leading to respiratory acidosis
• C. Hyperventilation
• D. Barotrauma

Answer: (B)

The main idea is that a nonrebreather mask relies on one-way valves to keep exhaled CO2 out of the inhaled gas. If the valve is stuck closed, exhaled gas can’t exit properly and CO2 gets trapped in the mask, causing the patient to rebreathe CO2 with each breath. This leads to hypercapnia and respiratory acidosis because carbon dioxide accumulates in the blood, lowering pH and stressing the respiratory system.

While the mask can still deliver high oxygen levels, the danger here is the buildup of CO2 rather than a lack of oxygen. Barotrauma isn’t a typical risk with this setup, and hyperventilation isn’t the primary consequence of a stuck valve.