Which parameter is increased by applying PEEP during ventilation?

Applying Positive End-Expiratory Pressure (PEEP) during mechanical ventilation primarily increases Functional Residual Capacity (FRC). FRC is the volume of air remaining in the lungs at the end of passive expiration. When PEEP is added, it prevents the alveoli from fully collapsing at the end of expiration, thereby enhancing lung inflation and increasing the amount of air that remains in the lungs. This can help recruit collapsed or partially collapsed alveoli, improving gas exchange and oxygenation.

By increasing FRC, PEEP effectively increases the lung's reserve capacity for gas exchange, which is especially beneficial for patients experiencing conditions like Acute Respiratory Distress Syndrome (ARDS) or other forms of lung injury where recruitment of collapsed areas of the lung is crucial for improving oxygenation. In this way, the application of PEEP enhances overall lung mechanics and efficiency.

Other parameters such as respiratory rate, tidal volume, and peak inspiratory pressure may be influenced by various factors during ventilation but are not directly increased as a consequence of applying PEEP.