What is the primary concern with an open pneumothorax?

An open pneumothorax occurs when there is a breach in the chest wall that allows air to enter the pleural space, the area between the lung and the chest wall. The primary concern in this situation is that the influx of air can disrupt the pressure balance that is necessary for the lungs to expand properly during inhalation. When air accumulates in the pleural space, it leads to lung collapse on the affected side because the lung can no longer stay inflated against the chest wall.

In contrast to other choices, loss of blood volume primarily relates to traumatic injuries that cause hemorrhage, fluid accumulation in the lungs signifies conditions like pulmonary edema, and excessive coughing may occur due to various irritants but is not the main concern with an open pneumothorax. The critical issue, therefore, is the need to address the airway and breathing to prevent respiratory failure, making the management of an open pneumothorax urgent and focused on sealing the chest wall breach, thereby allowing the lung to re-expand.