This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anaesthesia, Subject name: Anaesthesia
[{'content': 'All are true about thiopentone except \nSelect and explain. \nA. Na2CO3 is a preservative, B. contraindicated in porphyria, C. Agent of choice in shock, D. Has cerebroprotective action', 'role': 'user'}, {'content': "Answer: C \nExplanation: In situations where the baroreceptor response will be blunted or absent (eg, hypovolemia, congestive hea failure, b-adrenergic blockade), cardiac output and aerial blood pressure may fall dramatically due to uncompensated peripheral pooling of blood and direct myocardial depression. So, sodium thiopental is contraindicated in shock. Ref: Morgan & Mikhail's clinical anesthesiology 6e", 'role': 'assistant'}]