This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
[{'content': 'In which of the following condition, flat capnogram is NOT seen? \nSelect and explain. \nA. Apnea, B. Complete laryngospasm, C. Foreign body obstructing the upper airway, D. None of the above', 'role': 'user'}, {'content': "Answer: D \nExplanation: Capnography is a valuable monitor of the pulmonary, cardiovascular, and anesthetic breathing systems. Capnographs in common use rely on the absorption of infrared light by CO2. A value commonly repoed on the capnography device is the end-tidal CO2 (the maximum CO2 concentration at the end of each tidal breath, or ETCO2). A flat-line capnogram can be due to either apnea, upper airway obstruction, or complete laryngospasm. Ref: Miner J.R. (2011). Chapter 41. Procedural Sedation and Analgesia. In J.E. Tintinalli, J.S. Stapczynski, D.M. Cline, O.J. Ma, R.K. Cydulka, G.D. Meckler (Eds), Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e.", 'role': 'assistant'}]