<prompt> Flat capnogram is seen in all except:-Disconnection of endotracheal tubeAccidental extubationVentilation failureEndobronchial intubation  <response>: A sudden drop of ET Co2 to near Zero followed by absence of a Co2 waveform heralds a potentially life threatening problem. Differential diagnosis Dd. 1. Malposition of an Endotracheal tube into the pharynx or oesophagus. 2. Circuit Disconnection 3. Stoppage of ventilation 4. Cardiac arrest 5. Massive pulmonary embolism 