Introduction: COPD patients are exposed to endotracheal intubation and mechanical ventilation during general anaesthesia for various surgical interventions. In order to delineate the pathophysiology at molecular level, mini braonchoalveolar lavage (BAL) fluid was collected from these patients during mechanical ventilation and metabolomics profile of this was analyzed using nuclear magnetic resonance spectroscopy. Methods: 20 adult COPD patients (GOLD stage II and III) were enrolled in this prospective observational pilot study, which is the first study in which mini BAL fluid was utilized for assessing metabolomics of COPD patients undergoing mechanical ventilation during general anaesthesia for various surgical procedures. During NMR spectroscopy, several 1D and 2D spectra such as 1H, COSY and HSQC were carried out to identify various metabolites. Results: NMR spectra between 2 groups of samples (after intubation and before extubation) showed a slight difference on visual inspection in H1 D spectral analysis. There was slight increase in concentration of some metabolites (betaine, serine, aspartate, lysine/arginine and glucose) in “before extubation” samples. But 2D assignment techniques demonstrated no significant difference between 2 groups of samples. Conclusion: No change in lung metabolomic profile of COPD patients could be detected after endotracheal intubation and mechanical ventilation during surgery of 3 to 5 hours duration. We can also infer that optimized COPD grade II and grade III patients do not undergo metabolomic change in lungs during 3 to 5 hours of mechanical ventilation.