This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Maintenence level of Mixed venous oxygen saturation in shock must be \nSelect and explain. \nA. >70%, B. 50-70%, C. 40-50%, D. <40%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mixed venous oxygen saturation The percentage saturation of oxygen returning to the hea from the body is a measure of the oxygen delivery and extraction by the tissues. Accurate measurements is analysis of blood drawn from a long central line placed in the right atrium Normal mixed venous oxygen saturation levels are 50-70%. Levels below 50% indicate inadequate oxygen delivery and increased oxygen extraction by the cells. This is consistent with hypovolemic or cardiogenic shock. Ref: Bailey and love 27th edition Pgno: 17', 'role': 'assistant'}]