What is the primary goal of using PEEP in mechanically ventilated patients?

Using PEEP (Positive End-Expiratory Pressure) in mechanically ventilated patients is primarily aimed at enhancing oxygenation. PEEP helps maintain positive pressure in the lungs at the end of expiration, preventing the alveoli from fully collapsing. This increases functional residual capacity (FRC), which results in a larger surface area for gas exchange. By keeping the alveoli open, PEEP improves ventilation/perfusion matching and helps to increase the amount of oxygen delivered to the bloodstream.

Elevating FRC can also help in recruiting collapsed or under-ventilated lung units, thus facilitating better oxygenation. Additionally, the improved lung mechanics provided by PEEP can lead to reduced shunting and better overall oxygenation status in the patient.

While the application of PEEP can help with some of the other factors, such as preventing airway collapse by keeping the airways open, its primary purpose and most significant effect is on enhancing oxygenation in those who are mechanically ventilated.