A patient with an endobronchial tumor and critical airway obstruction developed hypoxia and hypercarbia and, subsequently, cardiac arrest during a palliative laser core-out excision. The differential diagnosis included tension pneumothorax, as well as airway obstruction due to swelling of residual tumor or to blood clots. In this case, empiric needle decompression could have had deleterious consequences. Immediate bedside lung ultrasonography provided real-time information leading to the stabilization of the patient. This case provides compelling motivation for anesthesiologists to acquire this easily learned skill.