This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': 'Which of the following is NOT seen in morbidly obese sleep apnea patient? \nSelect and explain. \nA. Polycythemia, B. Hypoxaemia, C. Rt. Ventricular failure, D. Lt. Ventricular failure', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (C) Rt. Ventricular failure # Heart Failure leads to increased left ventricular (LV) filling pressure.> Resulting pulmonary congestion activates lung vagal irritant receptors, which stimulate hyperventilation and hypocapnia.> Superimposed arousals cause further abrupt increases in ventilation and drive PaCO2 below the threshold for ventilation, triggering a central apnea.> Central sleep apneas are sustained by recurrent arousals resulting from apnea-induced hypoxia and the increased effort to breathe during the ventilatory phase because of pulmonary congestion and reduced lung compliance.> Although central apneas have a different pathophysiology than obstructive apneas and are not associated with the generation of exaggerated negative intrathoracic pressure, they both increase sympathetic nervous system activity (SNA).> Consequent increases in blood pressure (BP) & heart rate (HR) increase myocardial O2 demand in the face of reduced supply.> This chain of events contributes to a pathophysiological vicious cycle.', 'role': 'assistant'}]