What should you do if someone has a sucking chest wound?

In the case of a sucking chest wound, the most appropriate action is to cover the wound with a non-porous material. This is essential because a sucking chest wound can result in the loss of negative pressure in the thoracic cavity, leading to a collapse of the lung (pneumothorax) and potentially compromising the patient's ability to breathe. By applying a non-porous material, you create a seal that helps to prevent air from entering the pleural space during inhalation, which is critical for allowing the lung to reinflate or stabilize.

Using a porous material could allow air to enter the wound and worsen the pneumothorax, while applying a tourniquet is not appropriate since this strategy is designed for limb injuries with significant blood loss, not airway or chest wounds. Leaving the wound uncovered would similarly allow air to enter uncontrollably, further complicating the situation. Additionally, using a cold compress does not address the primary concern of sealing the wound to maintain lung function and should not be applied in this scenario.