Which observation is considered an indicator of esophageal intubation?

• A. Good chest excursion with ventilations
• B. Absence of gurgling sounds over the epigastrium
• C. The patient produces vocal noises after intubation
• D. Positive end-tidal CO2 detection using waveform capnography

Answer: (C)

The observation being tested is how to identify an esophageal intubation from clinical signs after attempting to place an endotracheal tube. When the tube is correctly in the trachea, ventilation leads to visible chest rise and, if you monitor with waveform capnography, a clear capnography trace showing CO2. In that situation, phonation is typically suppressed because the tube passes through the vocal cords and air flow to the vocal tract is interrupted.

If the patient starts producing vocal noises after the attempt, it suggests the airway is not secured in the trachea and the tube may be in the esophagus. The vocal cords are still in play, and phonation can occur because air is not being delivered into the lungs through the trachea.

The other observations fit more with proper airway confirmation or with a tube in the trachea: good chest excursion points to effective ventilation through the trachea, absence of gurgling over the epigastrium argues against air entering the stomach (which would happen with esophageal placement), and a positive end-tidal CO2 waveform confirms tracheal placement rather than esophageal.