How does PEEP help prevent intraoperative atelectasis?

How does PEEP help prevent intraoperative atelectasis?

• A. By increasing respiratory rate to improve oxygenation.
• B. By delivering high FiO2.
• C. By reducing end-expiratory pressure.
• D. By maintaining positive pressure at end expiration, increasing functional residual capacity, and improving oxygenation.

Answer: (D)

PEEP prevents intraoperative atelectasis by holding the lungs at positive pressure at the end of expiration, which keeps alveoli open rather than allowing them to collapse. This recruitment and stabilization of alveoli raise the functional residual capacity, creating a larger reservoir of air for gas exchange and reducing the shunt, leading to better oxygenation. In anesthesia, where lung volumes tend to fall and dependent regions tend to collapse, this positive end-expiratory pressure helps maintain open airways across the lungs. Increasing respiratory rate doesn’t address alveolar collapse directly, and a high FiO2 can contribute to absorption atelectasis rather than prevent it. Reducing end-expiratory pressure would promote collapse, not prevent it.

PEEP prevents intraoperative atelectasis by holding the lungs at positive pressure at the end of expiration, which keeps alveoli open rather than allowing them to collapse. This recruitment and stabilization of alveoli raise the functional residual capacity, creating a larger reservoir of air for gas exchange and reducing the shunt, leading to better oxygenation. In anesthesia, where lung volumes tend to fall and dependent regions tend to collapse, this positive end-expiratory pressure helps maintain open airways across the lungs.

Increasing respiratory rate doesn’t address alveolar collapse directly, and a high FiO2 can contribute to absorption atelectasis rather than prevent it. Reducing end-expiratory pressure would promote collapse, not prevent it.