What happens to tidal volume when lung compliance decreases during mechanical ventilation with Pressure Control Ventilation (PCV)?

• A. Peak pressure will increase.
• B. Peak pressure will decrease.
• C. Tidal volume will increase.
• D. Tidal volume will decrease.

Answer: (D)

During pressure control ventilation (PCV), the ventilator delivers a set amount of pressure to the patient's airway for a predetermined duration. When lung compliance decreases, the lungs become stiffer and more difficult to inflate. This reduced compliance means that for the same applied pressure, the volume of air that can be delivered to the lungs will decrease.

In PCV, since the pressure is kept constant regardless of the compliance of the lungs, the impact of decreased compliance is reflected in the tidal volume. Essentially, as the compliance drops, the ability of the lungs to expand diminishes, leading to a lower tidal volume being delivered. This change is crucial in managing patients, as it highlights the importance of continuously monitoring lung mechanics and adjusting ventilator settings according to the patient’s condition and response to ventilation.