Nitric Oxide

Question 1

What is nitric oxide (NO)?

Answer 1

Nitric oxide is an endogenous, vasodilating substance that can
be found in smooth muscle cells and in endothelium.
Vasodilation is caused through the activation of guanylate
cyclase and protein kinases or through the resequestration of
intracellular calcium.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 2

What are the most common uses clinically for NO?

Answer 2

Management of V/Q mismatching and pulmonary hypertension.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 3

How is NO administered clinically?

Answer 3

As an inspired gas
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 4

How does NO differ from IV vasodilator therapy?

Answer 4

IV vasodilators produce nonselective systemic and pulmonary
vasodilation. NO produces vasodilation selectively to areas of
the pulmonary vasculature in contact with alveoli that are
ventilated, thus decreasing V/Q mismatching and improving
oxygenation.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 5

What limits the clinical use of NO?

Answer 5

NO is expensive and its delivery system is cumbersome. NO
delivery systems necessitate a proper scavenging system in
order to limit exposure to personnel and it requires the constant
monitoring of gas concentration.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 6

Can NO cause toxicity?

Answer 6

Yes. The free radical form of NO, NO2, is associated with lung
toxicity. NO can also lead to the formation of nitrosyl
hemoglobin which is converted to methemoglobin.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.

Question 7

List clinical uses of NO.

Answer 7

NO is used to treat patients with primary pulmonary
hypertension, cardiac disease, lung transplants, heart
transplants, ARDS, idiopathic pulmonary hypertension,
congenital heart disease.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 969.