Neonatal Nurse Practitioner Practice Exam

How is inspiration controlled in Pressure Support Ventilation (PSV)?

1. By preset tidal volumes regardless of compliance and resistance

2. By the infant's own respiratory rate and effort

3. By preset pressure settings with tidal volume depending on compliance and resistance

4. By continuous positive pressure throughout the breathing cycle

The correct answer is: By preset pressure settings with tidal volume depending on compliance and resistance

In Pressure Support Ventilation (PSV), inspiration is primarily controlled by the preset pressure settings, allowing the ventilator to assist the infant's breathing effort during inspiration. When the infant initiates a breath, the ventilator delivers a set amount of pressure to help overcome the resistance of the airway and the compliance of the lung, which can vary based on the individual patient’s condition. The tidal volume that the infant actually receives during this phase of ventilation is influenced by the combination of the set pressure and the infant's own lung mechanics, including compliance and resistance. Therefore, the volume of air delivered can fluctuate depending on these factors, making the tidal volume not fixed but rather variable depending on the infant’s situation. Understanding this mechanism is crucial for neonatal care, as it ensures that the infant receives adequate assistance while allowing them to maintain some degree of independent respiratory effort, which is vital for their development. The other options do not accurately reflect the control dynamics in PSV: fixed tidal volumes don’t adapt to individual circumstances, while continuous positive pressure is not the method by which the ventilator supports inspired breaths in this mode.