What is the purpose of positive end expiratory pressure (PEEP)?

The purpose of positive end expiratory pressure (PEEP) is to apply a specified amount of pressure to the airways at the end of expiration. This elevated end-expiratory pressure helps to prevent the collapse of alveoli, which can lead to atelectasis (the complete or partial collapse of the lung). By maintaining a certain amount of pressure, PEEP improves gas exchange by keeping the alveoli open longer, allowing for better oxygenation and ventilation.

This mechanism is particularly beneficial in patients with respiratory distress or conditions such as Acute Respiratory Distress Syndrome (ARDS), where there is a need to maintain lung volume and optimize oxygenation. The application of PEEP can also contribute to an improved ventilation-perfusion ratio, which enhances the overall efficiency of the lungs during mechanical ventilation.

The other choices do not accurately represent the main function of PEEP. Increasing tidal volume focuses on the amount of air moved during each breath, which is a different concept. Stimulating respiratory reflexes pertains to the neural control of breathing rather than the mechanical aspect of maintaining lung expansion. Reducing oxygen flow conflicts with the fundamental purpose of PEEP, which is to improve oxygenation by enhancing lung function.