This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anaesthesia, Subject name: Pharmacology
[{'content': 'Intravenous regional anaesthesia is suitable for: \nSelect and explain. \nA. Ohopedic manipulation on the upper limb, B. Vascular surgery on the lower limb, C. Head and neck surgery, D. Caesarian section', 'role': 'user'}, {'content': 'Answer: A \nExplanation: IVRA is indicated for procedures on upper limb or lower limb of less than one hour duration. - it consist of inj. of LA in vein of torniquet occluded limb - drug diffuses from vascular bed to non-vascular tissue such as nerve endings - regional anesthesia is produced in 2-5min. and last for a min. after deflating the torniquet - bupivacaine should never be used because of its cardiotoxicity', 'role': 'assistant'}]