Kaushik Saha1, Sumitra Basuthakur2, Debraj Jash3, Arnab Maji3. 1. Department of Pulmonary Medicine, Burdwan Medical College and Hospital, Burdwan, West Bengal, India. 2. Department of Pulmonary Medicine, Kolkata Medical College and Hospital, Kolkata, West Bengal, India. 3. Department of Pulmonary Medicine, NRS Medical College and Hospital, Kolkata, West Bengal, India.