A male involved in a motor vehicle accident was found alert and stable at the scene but complaining of chest pain. He says he was not wearing a seat belt and was suddenly thrown into the dashboard. In the emergency department, he is alert. His blood pressure is 140/80 mmHg, and he has a pulse of 100 beats per minute. The chest x-ray shows opacification of the left chest with a midline shift to the right. What is the next step in the management of this patient?