This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'A male patient has a sucking stab wound to the chest. Which action should the nurse take first? \nSelect and explain. \nA. Drawing blood for a hematocrit and hemoglobin level, B. Applying a dressing over the wound and taping it on three sides, C. preparing a chest tube insertion tray, D. Preparing to start an I.V. line', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The nurse immediately should apply a dressing over the stab wound and tape it on three sides to allow air to escape and to prevent tension pneumothorax (which is more life-threatening than an open chest wound). \nOnly after covering and taping the wound should the nurse draw blood for laboratory tests, assist with chest tube insertion, and start an I.V. line.', 'role': 'assistant'}]