What is the main difference between an open and closed pneumothorax?

The distinction between an open and closed pneumothorax primarily lies in the presence of an external wound. An open pneumothorax occurs when there is a breach in the chest wall, such as a stab or gunshot wound, allowing air to enter the pleural space through the skin. This can lead to communication between the external environment and the thoracic cavity, potentially causing severe respiratory distress and necessitating immediate medical intervention.

In contrast, a closed pneumothorax occurs without any external injury and typically results from conditions like ruptured alveoli due to trauma, underlying lung disease, or spontaneous occurrences. The pleural space becomes filled with air, but without an external pathway for air entry or exit.

Understanding this key difference is critical for recognizing the clinical implications and management strategies for each type of pneumothorax. While the severity of each can vary based on individual circumstances, the presence of an external wound characterizes an open pneumothorax, making the first option the most accurate representation of the difference between the two conditions.