This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intravenous Anesthetic Agents, Subject name: Anaesthesia
[{'content': 'Which of the following intravenous anaesthetic causes increase in cerebral O2 tension. \nSelect and explain. \nA. Thiopentone, B. Propofol, C. Ketamine, D. Etomidate', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ketamine increases cerebral oxygen consumption, cerebral blood flow and intracranial pressure - thus avoided in head injury patient Ketamine administration may be associated with lacrimation and salivation which can be attenuated by premedication with an anticholinergic agent such as glycopyrrolate. Etomidate, propofol, and thiopentone decrease CMRO2, CBF, and ICP.', 'role': 'assistant'}]