Which description best captures the mechanism of the chest drainage device's one-way feature?

Which description best captures the mechanism of the chest drainage device's one-way feature?

• A. Forces bidirectional drainage
• B. Allows air to exit but not re-enter
• C. Drains only blood
• D. Drains only fluid

Answer: (B)

The one-way feature acts as a unidirectional valve in the chest drainage system. It is designed to vent air from the pleural space while preventing atmospheric air from flowing back in during inspiration. This protects the lung from re-collapse and avoids re-entry of air that could worsen a pneumothorax. In practice, a flutter valve or underwater seal achieves this by opening to let air escape when intrapleural pressure is higher than ambient, and closing to block backflow when the pressure reversed. So, the best description is that it allows air to exit but not re-enter. The system isn’t about draining only blood or only fluid, and it doesn’t enforce bidirectional drainage.

The one-way feature acts as a unidirectional valve in the chest drainage system. It is designed to vent air from the pleural space while preventing atmospheric air from flowing back in during inspiration. This protects the lung from re-collapse and avoids re-entry of air that could worsen a pneumothorax. In practice, a flutter valve or underwater seal achieves this by opening to let air escape when intrapleural pressure is higher than ambient, and closing to block backflow when the pressure reversed. So, the best description is that it allows air to exit but not re-enter. The system isn’t about draining only blood or only fluid, and it doesn’t enforce bidirectional drainage.