What is adjusted to change the tidal volume when a patient is on pressure control ventilation (PCV)?

In pressure control ventilation (PCV), the primary control mechanism for adjusting the tidal volume delivered to the patient is the set pressure. This mode of ventilation is designed to deliver a specified pressure during inspiration, and the volume of air (tidal volume) that the patient receives can vary depending on the compliance and resistance of the patient’s lung mechanics at that set pressure.

When the set pressure is increased, the pressure waveform applied to the airways allows more air to flow into the lungs until that pressure is reached. If the lung compliance decreases, achieving a specific tidal volume becomes more difficult; therefore, adjusting the set pressure upward can help ensure that the desired tidal volume is achieved. Conversely, if the compliance improves, a lower set pressure may suffice to deliver the same tidal volume.

Other factors, such as frequency settings, inspiratory time, and minute volume, can influence ventilation but do not directly control the tidal volume like the set pressure does. Frequency can influence the total ventilation but does not change the volume delivered per breath directly; inspiratory time can affect the distribution of tidal volume but is primarily determined by the set pressure, and minute volume is an overall measure rather than a direct adjuster of the tidal volume for each breath. This makes the set pressure