Immediately following endotracheal intubation you notice free, effortless return of air after squeezing the device. This indicates that?

• A. You have intubated the esophagus.
• B. You have entered the left mainstem bronchus.
• C. You have intubated the trachea.
• D. None of the above

Answer: (C)

When you can ventilate easily right after placing the tube, with air moving freely into the lungs and the chest rising, it means the tube is in the trachea and the airway is patent. This immediate, effortless ventilation shows that air is reaching the lungs rather than entering the stomach or causing obstruction. If the tube were in the esophagus, ventilation would be poor or would mostly inflate the stomach, leading to gastric distention and little or no chest rise. If the tube were in a mainstem bronchus, ventilation would predominantly go to one lung, often with asymmetric chest movement and breath sounds. The described smooth ventilation points to correct tracheal placement.