What does a persistently absent capnography trace after intubation indicate?

• A. Possible esophageal intubation or severely impaired pulmonary perfusion; reassess airway and confirm tube position.
• B. Normal placement with quick capnography spike.
• C. Equipment malfunction only.
• D. The patient has high metabolic rate causing false-negative.

Answer: (A)

A persistently absent capnography trace after intubation means no CO2 is being detected in exhaled air, despite ventilation. This points to two main possibilities. One is that the endotracheal tube is not in the trachea—esophageal intubation—so air is going into the stomach and little to no CO2 returns. The other is severely impaired pulmonary perfusion, where there is little or no blood flow to pick up and transport CO2 to the lungs (as can happen in cardiac arrest or massive pulmonary embolism), leading to no detectable end-tidal CO2 even with a correctly placed tube.

The essential response is to reassess the airway and confirm tube position immediately. Check for bilateral breath sounds and symmetric chest rise, listen for air entry, and use available methods to verify placement (capnography waveform again, colorimetric CO2 detector, or rapid imaging if feasible). If the tube is not in the trachea, reposition and re-ventilate; if perfusion is the issue, address circulation while ensuring the airway remains secured.