An elderly lady, with background history of chronic obstructive lung disease, previous history of stroke, hypertension, type 2 diabetes, smoker of 30 pack years, was admitted to hospital due to 2 days history of productive cough of greenish sputum, wheezy, increasing in shortness of breath, intermitent feverish. On arrival, her oxygen saturation on room air was around 86%, with increased in respiratory rate to around 24 / minute. On examination of her lung field, there was scattered wheeze throughout the lung field, with coarse crackles on right base. Chest x-ray confirmed right lower lobe consolidation. Her ABG (Arterial blood gas), showed type 2 respiratory failure with slight acidosis. Pateint was treated for infective exacerbation of COPD. Apart from antibiotic, steroid, and nebuliser, what other important treatment that should be given to this patient ??