Final answer:
The patient likely has a tension pneumothorax and needs immediate medical attention including a vented dressing and monitoring for cardiac arrest, in which case CPR would be necessary.
Step-by-step explanation:
A 17-year-old male who was shot in the chest and is presenting with a sucking wound is likely experiencing a tension pneumothorax, a life-threatening condition that occurs when air is trapped in the pleural space and pushes on the lung and other structures, which can lead to a drop in blood pressure and respiratory distress. Immediate medical intervention is needed, which should include sealing the wound with a vented dressing to prevent air from entering the chest with each breath but allowing air to escape.
Meanwhile, the patient must be monitored for signs of worsening, such as increased shortness of breath, low blood pressure, and altered mental status. If the patient's heart stops, CPR (cardiopulmonary resuscitation) might be required, which involves applying pressure in the correct location on the sternum between the lines at T4 and T9, at a depth of 5 cm and at a rate of 100 compressions per minute.