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: Surgery
Nitrogen washout curve is used in 
Select and explain. 
A. Vital capacity, B. Inspiratory reserve volume, C. Functional residual capacity, D. Residual volume
C: Functional residual capacity
Answer: C: Functional residual capacity 
Explanation: C. i.e. (Functional residual capacity) (62- 63 Anesthesia - Janes - Duke 3rd)Functional residual capacity (RV + ERV)* Measuring FRC is the cornerstone for determining the remainder of the lung volumesThree different technique1. Helium equilibration /dilution2. Nitrogen wash out3. Body plethysmography* Plethysmography is most accurate for determining FRC in patients with COPD and applies Boyles law