Which of the following best describes Pressure Support Ventilation (PSV)?

Pressure Support Ventilation (PSV) is a mode of mechanical ventilation designed to assist patients who are able to initiate their own breaths but may require help to overcome the resistance of the ventilator and the breathing circuit. In PSV, the ventilator delivers a set positive pressure during spontaneous breaths. This means that when the patient initiates a breath, the ventilator provides a boost of pressure to support that effort, facilitating adequate tidal volume and reducing the work of breathing.

This mechanism is particularly beneficial for patients with respiratory muscle weakness or those weaning from mechanical ventilation, as it allows them to breathe more comfortably while still providing adequate support. The patient maintains control over their breathing rate and depth, which encourages spontaneous breathing efforts, leading to improved respiratory function and weaning success.

The other choices are not accurate representations of PSV. For example, constant tidal volume is achieved in different modes of ventilation, but it is not the hallmark of PSV, which varies with patient effort. Also, delivering less pressure than required does not align with the purpose of PSV, which is to assist with pressure to meet the patient's inspiratory needs. Lastly, controlling the rate and rhythm of ventilation is characteristic of other ventilatory modes like Assist-Control, rather than the supportive nature of PSV.