In pressure limited ventilation, what occurs once the pre-set peak inspiratory pressure (PIP) is reached?

In pressure limited ventilation, once the pre-set peak inspiratory pressure (PIP) is reached, the ventilator maintains that PIP throughout the inspiratory phase. This means that regardless of changes in lung compliance or airway resistance, the pressure will not exceed the predetermined limit. Maintaining the pressure ensures that each breath delivered adheres to safety limits intended to protect the lungs from barotrauma and overdistension.

This mechanism allows for variable tidal volumes during each breath, which can be beneficial in situations where lung mechanics are changing, such as in patients with acute respiratory distress syndrome (ARDS). The ability to prevent excessive pressure aids in optimizing ventilation while avoiding potential damage to the alveoli.

In contrast, the other options do not accurately describe the behavior of pressure limited ventilation. For instance, the pressure is not increased for the entire cycle; it caps at the set PIP. Additionally, the flow rate is determined by the patient's needs and the set pressure, not actively decreased after PIP is reached. Lastly, the ventilator does not switch to volume control once PIP is reached; it continues to operate in a pressure-controlled mode, maintaining the set pressure limit.