A 58-year-old male with a 40 pack-year smoking history presents with progressive dyspnea and stridor over 3 weeks. Laryngoscopy reveals a large infiltrative mass involving the anterior two-thirds of the vocal cords with subglottic extension. CT chest shows a 3 cm laryngeal mass with no distant metastases. The patient is scheduled for total laryngectomy with adjuvant radiotherapy. However, 48 hours post-operatively, he develops acute respiratory distress, subcutaneous emphysema in the neck, and a sudden gush of air from the surgical site. On examination, there is loss of the normal tracheal air column on imaging. What is the most likely immediate complication that has occurred?