This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2017, Subject name: Surgery
How will you check the functioning of an ICD tube? 
Select and explain. 
A. By observing for continuous air bubbles coming out of the underwater drain, B. By observing the movement of air water column in the tube during respiration, C. By taking X ray chest repeatedly, D. By auscultation
B: By observing the movement of air water column in the tube during respiration
Answer: B: By observing the movement of air water column in the tube during respiration 
Explanation: Chest drainage system: Follow-up: Patency of chest tube is assessed by observing the oscillations in water seal chamber with respiratory movements. Position of chest tube & resolution of intrapleural air or liquid is checked by x-ray (AP & cross table lateral). Tube should be pulled back if it crosses the mediastinum Removal: Chest tubes are generally removed when there has been air or fluid drainage of <200 ml in 24 hours for >24 hours .