You are transporting a 45-year-old male patient who was involved in a high-speed car accident. He is intubated and mechanically ventilated. During the flight, you notice a sudden drop in O2 saturation to 85%, increased peak airway pressures, and diminished breath sounds on the left side. Which of the following is the most likely cause of this patient's acute respiratory distress?
Pneumothorax
Pulmonary Embolism (PE)
Acute Respiratory Distress Syndrome (ARDS)
Aspiration