Pulmonary Vasodilators Flashcards
What are the four pulmonary vasodilators?
Nitrous oxide, Eproprostenol (Caripul), Alprostadil, and Sildenafil
Which pulmonary vasodilators are inhaled?
Nitrous oxide and Epoprostenol.
Which pulmonary vasodilator is given IV?
Alprostadil
Which pulmonary vasodilator is given orally?
Sildenafil
What are the two main reasons we want to vasodilate in the lungs?
To decrease resistance against the right side of the heart and to redistribute pulmonary blood flow through the lungs (by expanding vessels to control where it goes)
What are the effects of endogenous NO on the body?
Regulates vascular tone and inhibits platelet aggregation.
What is the half life on NO in the bloodstream?
0.1-5 seconds
Why is the short half life of NO an advantage?
Vasodilation will occur locally but the NO will be inactivated before it reaches systemic circulation.
What inactivates NO?
NO binds with hemoglobin, inactivating it.
Describe the negative effects of NO.
NO is unstable so it easily combines with oxygen to form NO2 (nitric acid). If Nitric acid is being delivered we may cause acid pneumonitis in pts.
How do we control NO delivery?
By measuring inspiratory flow and injecting a proportional amount of NO into the inspiratory limb of the vent. Concentration is measured prior to breath entering patient, ensuring exact delivery.
What device do we use for NO delivery.
The iNOmax machine.
What is the initiating dose of NO and the effective dose?
20ppm initiating, 1-2 ppm effective.
What are the two primary uses for NO?
To reverse or decrease pulmonary hypertension or right heart failure and to improve oxygenation due to hypoxic respiratory failure.
When administering NO over a long period of time, what happens to endogenous NO production?
Endogenous production is reduced or halted. Sudden discontinuation may result in rebound hypertension or hypoxemia, so it should be slowly weaned.
What family does Epoprostenol belong to?
Prostacyclins (pulmonary vasodilator)
What does Epoprostenol do?
Causes vasodilation and inhibits platelet aggregation.
What is the half life of Epoprostenol?
30-40 seconds.
How is Epoprostenol delivered?
It comes as a dry powder and must be reconstituted into a liquid for delivery via neb. The neb is controlled by a syringe in a pump.
What are some drawbacks to using Epoprostenol?
As it is a neb, we don’t know the exact concentration. It is also very basic so we must be careful not to instill any into the patient.
What advantages does Epoprostenol have over NO?
There is no rebound hypertension when discontinued, does not cause inflammation (unless accidentally instilled) and has a low cost compared to NO.
What family does Alprostadil belong to?
Prostacyclins (pulmonary vasodilator)
What is Alprostadil used for?
Some babies are born with congenital heart defect, so ductus arteriosus must be prevented from closing (called patent ductus arteriosus or PDA). Alprostadil is given via infusion through a central line to maintain PDA
What family does Sildenafil belong to?
cGMP phosphodiesterase inhibitor (pulmonary vasodilator)
