This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Monitoring in Anesthesia, Subject name: Anaesthesia
Pulmonary changes in lateral position in the anaesthetized patient? 
Select and explain. 
A. Dependent lung is relatively over ventilated and over-perfused, B. Dependent lung is relatively over ventilated and under-perfused, C. Dependent lung is relatively under ventilated and over-perfused, D. Dependent lung is relatively under ventilated and under-perfused
C: Dependent lung is relatively under ventilated and over-perfused
Answer: C: Dependent lung is relatively under ventilated and over-perfused 
Explanation: In the anaesthetized patient : Dependent lung is relatively under-ventilated and over-perfused Non-dependent lung is over-ventilated and under-perfused. This leads to a generally well tolerated increase in ventilation-perfusion inequality but can cause hypoxaemia in compromised patients.