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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Flat capnogram found in A/E –
assistant
The correct answer is  All the four options given in the question can cause flat Capnography. But, bronchospasm is the single best answer here as only severe bronchospasm (causing complete respiratory obstruction) can cause a flat capnograph. However, bronchoconstriction is usually partial which causes a steep plateau in capnograph (not flat capnograph).
A flat capnograph is seen in accidental extubation, equipment failure, disconnection (dissociation) of a tube, total occlusion, mechanical ventilation failure, cardiac arrest, severe bronchospasm completely obstructing the airway and complete occlusion of pulmonary circulation.