Final answer:
Administering high-concentration oxygen is the initial care for a patient with chest pain following a motor vehicle accident. Treating potential cardiac issues and ensuring adequate oxygenation to the organs is the priority before treating potential injuries such as a sternum fracture.
Step-by-step explanation:
The initial care for a 65-year-old male complaining of chest pain when breathing and tenderness of the sternum following a motor vehicle crash should include administering high-concentration oxygen. This is a priority in trauma care and potential cardiac issues to ensure that the tissues, especially vital organs like the heart and brain, are receiving adequate oxygen. It is important not to stabilize the sternum or position the patient on his side initially, as these actions can cause further injury. Administering the patient's prescribed nitroglycerin is typically for ongoing cardiac chest pain management, such as angina pectoris, but it would not be the immediate step in a traumatic scenario without a confirmed diagnosis. Recognizing the symptoms of an acute myocardial infarction (MI) is crucial, as it can present with similar symptoms and immediate medical intervention is necessary to prevent permanent damage or fatality.