Nitric Oxide cannot be used in which scenario?

• A. Suspected bowel perforation
• B. Severe congestive heart failure
• C. Hypertension
• D. Obesity

Answer: (A)

Nitrous oxide should not be used when there is suspected bowel perforation because it diffuses rapidly into gas-filled spaces and expands them. The bowel lumen and any gas they contain can take in more gas from the bloodstream faster than it leaves, so administering nitrous oxide would increase the volume and pressure inside the bowel. In the setting of a perforation, this can worsen distension, elevate intra-abdominal pressure, and potentially worsen leakage or cause harm. The other scenarios listed do not involve a closed gas-filled space that can be expanded by the gas, so there’s no inherent gas-diffusion risk there.