Neonatal Nurse Practitioner Practice Exam

What is the mechanism of exhalation in High-Frequency Jet Ventilation (HFJV)?

1. Active propulsion from mechanical devices

2. Passive lung expansion mechanisms

3. Direct muscle contractions

4. Lung recoil

The correct answer is: Lung recoil

In High-Frequency Jet Ventilation (HFJV), the mechanism of exhalation is primarily attributed to lung recoil. This process relies on the fundamental properties of the lung tissues, which inherently tend to return to their resting state after being distended. When jets of gas are delivered into the airways at high frequencies, they primarily assist in the inhalation phase, delivering a rapid influx of oxygen-rich air. During exhalation, the elastic properties of lung tissue play a crucial role. As the jets are turned off, the lung tissues naturally recoil and expel the carbon dioxide and other gases from the lungs. This passive mechanism does not require active contraction of respiratory muscles or external forces to facilitate the exhalation process, distinguishing it from other forms of ventilation that might involve more active mechanisms. Understanding this process is critical in managing neonates requiring HFJV, as it emphasizes the importance of recognizing how the ventilatory strategy works to ensure proper gas exchange and maintain adequate oxygenation and ventilation.