This is an example of one of the main risks with nasogastric tube insertion.
Due to the close relation of the openings of the oesophagus and the trachea, it is far too easy for NG tubes to pass into the respiratory system.
Remember too that on a CXR, the lung bases sit well below the projected level of the diaphragm so it is not safe to use unless the tube travels down the midline.
If this is not quickly recognised, and the tubes are used for medication or feeding, the patient is at significant risk of aspiration, pneumonitis and death.
Case originally uploaded by Dr Derek Smith and available here.