In severe pulmonary hypertension, nitrous oxide should be avoided because it can worsen pulmonary vascular resistance. Which statement is true?

In severe pulmonary hypertension, nitrous oxide should be avoided because it can worsen pulmonary vascular resistance. Which statement is true?

• A. It should be avoided due to potential PVR increase
• B. It is beneficial to reduce PVR
• C. It has no effect on PVR
• D. It always decreases PVR

Answer: (A)

In severe pulmonary hypertension, the pulmonary vessels are already constricted and the right ventricle is working hard to push blood through a high-resistance circuit. Any agent that raises pulmonary vascular resistance will worsen right-ventricular strain and can lead to decompensation. Nitrous oxide isn’t a pulmonary vasodilator; in susceptible patients it can increase pulmonary vascular tone and, through effects on ventilation–perfusion balance and oxygen delivery, potentially worsen PVR. Because it does not reliably lower PVR—and may actually raise it—nitrous oxide should be avoided in this setting. The other statements imply benefits or neutrality that don’t align with how nitrous oxide behaves in pulmonary hypertension.

In severe pulmonary hypertension, the pulmonary vessels are already constricted and the right ventricle is working hard to push blood through a high-resistance circuit. Any agent that raises pulmonary vascular resistance will worsen right-ventricular strain and can lead to decompensation. Nitrous oxide isn’t a pulmonary vasodilator; in susceptible patients it can increase pulmonary vascular tone and, through effects on ventilation–perfusion balance and oxygen delivery, potentially worsen PVR. Because it does not reliably lower PVR—and may actually raise it—nitrous oxide should be avoided in this setting. The other statements imply benefits or neutrality that don’t align with how nitrous oxide behaves in pulmonary hypertension.