Inhaled pulmonary vasodilators are a class of inhaled aerosol medications that are administered to treat pulmonary hypertension. As a Respiratory Therapist (or student), this is one of the drug classes that you must be familiar with.

We created this study guide to (hopefully) make the learning process easier for you. We listed out practice questions below for your benefit as well. So, if you’re ready, let’s get started.

Types of Inhaled Pulmonary Vasodilators

The three most common types of inhaled pulmonary vasodilators include:

  1. Nitric oxide
  2. Iloprost
  3. Treprostinil

At this time, these are the only three inhaled pulmonary vasodilators that have been approved by the FDA.

With that said, other agents are being studied and this can change at any given time.

Inhaled Nitric Oxide

Nitric oxide is a colorless, odorless gas that causes vascular smooth muscle relaxation which improves blood flow to ventilated alveoli.

It’s often indicated in adult patients to treat acute or chronic pulmonary hypertension.

Inhaled nitric oxygen may be administered to neonates as well in order to improve oxygenation.


Iloprost is also indicated for the treatment of pulmonary hypertension and can be administered with an I-neb inhaler.

It works by dilating the pulmonary arterial vascular beds and affects platelet aggregation.


Treprostinil is also indicated for the treatment of arterial pulmonary hypertension.

It can be administered using the Tyvaso Inhalation System which is an ultrasonic type of delivery device.

Inhaled Pulmonary Vasodilators Practice Questions:

1. Why are inhaled pulmonary vasodilators administered?
They are administered to treat pulmonary hypertension.

2. Has the use of inhaled nitric oxide gas to treat neonates with persistent pulmonary hypertension been approved by the FDA?
Yes, it has been approved.

3. Which two inhaled pulmonary vasodilators have been FDA approved for the treatment of pulmonary hypertension?
Iloprost and treprostinil

4. When is nitric oxide indicated?
It’s indicated for the treatment of neonates greater than 34 weeks of gestational age with hypoxic respiratory failure.

5. What is a brand of nitric oxide?

6. When is iloprost indicated?
It is indicated for the treatment of pulmonary hypertension.

7. How can iloprost be administered?
It can be administered with an I-neb nebulizer.

8. How does iloprost work?
It dilates the pulmonary arterial vascular beds and affects platelet aggregation.

9. What are some adverse effects of iloprost?
Pulmonary edema, syncope, headache, and increased cough.

10. When is treprostinil indicated?
It is indicated for the treatment of pulmonary arterial hypertension.

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11. What is a brand of treprostinil?

12. How is treprostinil administered?
It can be administered using an ultrasonic pulsed-delivery device known as a Tyvaso Inhalation System.

13. How does treprostinil work?
It dilates the pulmonary and systemic arterial vascular beds and inhibits platelet aggregation.

14. What is a potential negative side effect of treprostinil?
It may cause bronchospasm.

15. Can you mix treprostinil with other agents?
No, this drug should not be mixed.

16. Which drug is used to treat persistent pulmonary hypertension in neonates?
Nitric oxide

17. How does a nitric oxide treatment work?
It relaxes the vascular smooth muscle tissue by binding to the heme group of cytosolic guanylate cyclase which activates guanylate cyclase and increases cyclic guanosine monophosphate.

18. What happens when nitric oxide is inhaled?
It produces pulmonary vasodilation, reduces pulmonary artery pressure, and improves V/Q mismatching.

19. What is a contraindication of nitric oxide?
It is contraindicated in neonates with dependent right-to-left shunts.

20. What is a common adverse effect that occurs when nitric oxide is given?

21. What drug is indicated to increase walking distance in patients?
Treprostinil (Tyvaso)

22. What is the dose availability of treprostinil?
It comes in a 2.9 mL ampule which contains 1.74 mg of treprostinil (0.6 mg/mL).

23. What should you do if treprostinil is not tolerated well by the patient?
The dose should be reduced to 1-2 breaths per session.

24. When is it indicated to increase the dose of treprostinil to three breaths?
You can increase the dose every 1-2 weeks until a dose of nine breaths per session has been reached.

25. Does nitric oxide act as a pulmonary vasodilator, improve pulmonary blood flow, and improve the PaO2 level?
Yes, yes it does.

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26. How does nitric oxide affect systemic blood pressure?
It does not have an effect on systemic blood pressure.

27. Is nitric oxide a selective pulmonary vasodilator?
Yes, because it’s inhaled and only goes to the ventilated lung areas.

28. What is an indication of iNO?
Refractory hypoxemia related to an increased pulmonary artery pressure.

29. Name two more indication of iNO?
Right heart failure and an increased PVR.

30. What are the contraindications of iNO?
CHF, left heart failure, and methemoglobin reductase deficiency.

31. What is the standard initial dose for iNO?
20-40 ppm

32. What level should an iNO dose not exceed?
80 ppm

33. What dose is used for weaning and discontinuing iNO?
Less than 20 ppm

34. What is the half life of iNO?
Less than 5 seconds

35. Will methemoglobin level increase or decrease with iNO?
It may increase as a side effect.

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36. Will nitrogen dioxide levels increase or decrease with iNO?
They may increase as a side effect.

37. What happens if a patient is weaned too quickly from iNO?
Rebound pulmonary hypertension can occur.

38. Why does inhaled nitric oxide work so well?
It dilates blood vessels around the alveoli which helps to open them up.

39. Does inhaled nitric oxide improve V/Q mismatch and oxygenation?
Yes, yes it does.

40. What should you do before removing a patient from nitric oxide?
Before removing, make sure that the cylinder is turned off.

Final Thoughts

Hopefully, the information in this study guide has helped develop a better understanding of the inhaled pulmonary vasodilators. Again, this is a requirement for Respiratory Therapists.

We have another detailed guide on Airway Pharmacology that I think you will enjoy. Thanks for reading and, as always, breathe easy my friend.


The following are the sources that were used while doing research for this article: