One of the most important skills to grasp in combat medicine is the treating of a sucking chest wound. Not only is this one of the most common injuries in combat, it can cause both tension pneumonia (Collapse Lung) and is one of the few injuries that can stop the heart and force the body into irreversible shock. Along with this articular I'm including a video to what an actual sucking chest wound looks like in the link below. Those with weak stomach be cautioned.
Sucking Chest Wound