A client arrives at the emergency department with an open chest wound from a knife stabbing. What is the nurse's priority action?

An open chest wound (sucking chest wound) allows air to enter the pleural space with each inspiration, potentially collapsing the lung and causing a tension pneumothorax, which is life-threatening. The immediate priority is to cover the wound with an airtight (occlusive) dressing to prevent further air entry. In practice, a three-sided occlusive dressing is often preferred to allow air to escape but not enter; however, among the options given, covering the open area with an airtight bandage is the correct first action to stabilize the injury. Applying oxygen is important but is not the priority action because the open wound must be sealed first to prevent worsening pneumothorax. Obtaining a chest x-ray and blood gases is a diagnostic step that comes after immediate stabilization — it is not a priority action. Preparing for chest tube insertion may be necessary but is not the first step; the wound must be sealed before further interventions. The nursing principle here is to address the immediate life threat — air entry through the chest wall — before diagnostic or secondary interventions. Sealing the wound is the most direct action to prevent respiratory and hemodynamic collapse.