Certified Transport Registered Nurse Certification Practice Exam

How does nitric oxide improve oxygenation in the lungs?

1. By reducing airway resistance

2. By increasing blood flow to the alveolus

3. By increasing tidal volume

4. By dilating the bronchioles

The correct answer is: By increasing blood flow to the alveolus

Nitric oxide plays a crucial role in enhancing oxygenation in the lungs primarily by increasing blood flow to the alveoli. When administered, nitric oxide acts as a potent vasodilator specifically in the pulmonary circulation. This means it relaxes the smooth muscles around the blood vessels, leading to increased blood flow to well-ventilated areas of the lungs. By directing more blood to these areas, nitric oxide improves the matching of ventilation (air flow) and perfusion (blood flow), which is essential for optimal gas exchange. In areas of the lung where oxygen is readily available, enhanced blood flow ensures that a larger volume of oxygen enters the bloodstream, ultimately improving overall oxygenation levels in the body. This mechanism is particularly beneficial in conditions where there may be localized pulmonary issues, such as pulmonary hypertension, as it can improve oxygen delivery without significantly increasing work of breathing or causing widespread vasodilation in the systemic circulation.