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: Anaesthesia
A 72-year-old man undergoes resection of an abdominal aneurysm. He arrives in the ICU with a core temperature of 33degC (91.4degF) and shivering. Which of the following is a physiologic consequence of the shivering? 
Select and explain. 
A. Rising mixed venous O2 saturation, B. Increased production of CO2, C. Decreased consumption of O2, D. Rising base excess
B: Increased production of CO2
Answer: B: Increased production of CO2 
Explanation: Shivering is the physiologic effo of the body to generate heat to maintain the core temperature. In healthy persons, shivering increases the metabolic rate by 3 to 5 times and results in increased O2 consumption and CO2 production. In critically ill patients, these metabolic consequences are almost always counterproductive and should be prevented with other means employed to correct systemic hypothermia. In the presence of vigorous shivering, O2 debt in the muscles and lactic acidemia develop.