Which of the following inhaled gas is used to decrease pulmonary aery pressure in adults and infants?
**Core Concept**
The question is testing the understanding of inhaled gases used in the management of pulmonary hypertension. Inhaled gases can be used to decrease pulmonary artery pressure by inducing vasodilation or by reducing the oxygen tension in the lungs, which in turn reduces the right-to-left shunting of blood.
**Why the Correct Answer is Right**
Nitric oxide (NO) is an inhaled gas that is used to decrease pulmonary artery pressure in both adults and infants. It works by stimulating the production of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the pulmonary arteries, leading to vasodilation and a decrease in pulmonary artery pressure. This is particularly useful in patients with pulmonary hypertension who are resistant to other forms of treatment.
**Why Each Wrong Option is Incorrect**
**Option A:** Helium is an inert gas that is used to reduce the work of breathing in patients with severe respiratory disease, but it does not have a direct effect on pulmonary artery pressure.
**Option B:** Carbogen is a mixture of oxygen and carbon dioxide, and it is used to increase oxygen delivery to the tissues, but it does not have a direct effect on pulmonary artery pressure.
**Option C:** Nitrogen is an inert gas that makes up a large portion of the air we breathe, but it does not have a direct effect on pulmonary artery pressure.
**Clinical Pearl / High-Yield Fact**
Nitric oxide is a potent vasodilator that is used to decrease pulmonary artery pressure in patients with pulmonary hypertension. It is particularly useful in patients who are resistant to other forms of treatment.
**Correct Answer:** C. Nitric oxide is used to decrease pulmonary artery pressure in adults and infants.