This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Complications Of Anaesthesia, Subject name: Anaesthesia
Anesthetic agent contraindicated in raised ICT is? 
Select and explain. 
A. Ketamine, B. Sevoflurane, C. Thiopentone, D. Etomidate
A: Ketamine
Answer: A: Ketamine 
Explanation: Ans. is 'a' i.e., Ketamine * Ketamine increases cerebral metabolic rate, cerebral blood flow and intracranial tension.Neurophysiology and anaesthesiaA. Intravenous inducing anaesthetics# All intravenous inducing agents except for ketamine (i.e., etomidate, thiopentone, methohexitone and propofol) decrease cerebral metabolic rate, cerebral blood flow and intracranial tension. Maximum decrease in cerebral blood flow and cerebral protection is caused by thiopentone - IV agent of choice for neurosurgery.B. Inhalational agents# All inhalational agents: -i) Increase intracranial tension and cerebral blood flow.ii) Decrease cerebral metabolic rate - There by provide cerebroprotection.iii) Amongst inhalational agents, isoflurane provides maximum cerebroprotection, therefore it is the inhalational agent of choice for neurosurgery.C. Lidocaine# Lidocaine decreases ICT, Cerebral blood flow and metabolic rate.