This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'pH is 7.2; PCO2 12; PO2 55 most likely cause is - \nSelect and explain. \nA. Metabolic acidosis and respiratory alkalosis, B. Metabolic alkalosis, C. Respiratory acidosis, D. Respiratory alkalosis', 'role': 'user'}, {'content': "Answer: A \nExplanation: In this patient\npH\xa0→ Decreased (Normal 7.4)\nPCO2\xa0→ Decreased.\nFirst step\n\nDetermine whether it is acidosis or alkalosis.\nThe decrease in pH suggests acidosis.\n\nSecond step\n\nObserved HCO3-/PCO2 to determine the cause of acidosis or alkalosis\nOnly one value is mentioned and that too is not in sync with the pH\nPCO2 value of 12 indicates respiratory alkalosis\nBut the pH of the serum indicates acidosis, this suggests the presence of some other disorder besides the respiratory alkalosis which must be producing acidosis\nOption 'a' appears to be appropriate because the coexisting metabolic acidosis will cause a decrease in pH.", 'role': 'assistant'}]