The main factor for suspecting a tension pneumothorax is:

The main factor for suspecting a tension pneumothorax is a penetrating chest wound. In cases of penetrating trauma, there is a significant risk for the introduction of air into the pleural space, which can lead to a tension pneumothorax as the air cannot escape. This condition results in increased pressure within the thoracic cavity, collapsing the lung on the affected side and potentially compressing vital structures such as the heart and great vessels.

In contrast, while nonpenetrating chest wounds, blunt trauma, and rib fractures can also lead to pneumothorax, they are less directly associated with the rapid accumulation of air that characterizes tension pneumothorax. The mechanism of injury in these cases may not necessarily create a one-way valve effect that leads to the retention of air in the pleural space. Thus, penetrating wounds are a predominant concern for tension pneumothorax due to the nature of the injury allowing for air entry and resulting in life-threatening complications.