Elevations of which substance may be a sign of overdose in infants treated with nitric oxide?

• A. Blood Pressure
• B. Nitrogen Dioxide
• C. Oxyhemoglobin
• D. Methemoglobin

Answer: (B)

Inhaled nitric oxide therapy can form nitrogen dioxide when NO reacts with oxygen in the lungs. Nitrogen dioxide is a toxic gas, and rising levels indicate that the NO dose is too high or being delivered improperly. Therefore, elevated NO2 serves as a direct sign of potential overdose and prompts dose adjustment and closer monitoring. While methemoglobin can also become elevated with NO exposure, the most specific marker of overdose risk in this context is the rise in nitrogen dioxide.