Why is a three-sided occlusive dressing used for open chest wounds?

• A. It seals the wound completely to trap air
• B. It seals the wound to prevent air entry while allowing air to escape to avoid tension
• C. It prevents bleeding by applying constant pressure
• D. It protects the wound from contamination

Answer: (B)

Open chest wounds can allow air to be drawn into the pleural space during inhalation, which risks a pneumothorax that can worsen into a life-threatening tension pneumothorax. A three-sided occlusive dressing is designed to seal the wound on three sides, leaving one edge open to vent. This setup blocks air from entering the chest during inspiration but lets air escape during expiration, preventing air from accumulating and reducing the chance of tension building up. It’s about balancing seal to stop entry with a vent to prevent pressure buildup, not about trapping air completely or primarily stopping bleeding or contamination.