NPPB and Airway obstruction: CI, confidence interval; DM, diabetes mellitus; AF, atrial fibrillation; BNP, brain natriuretic peptide; FVC, forced vital capacity; GOLD, global initiative for obstructive lung disease; FEV1, forced expiratory volume 1; pH, potential of hydrogen; PaO2, partial pressure of oxygen; PaCO2, partial pressure of carbon dioxide; HCO3, bicarbonate