A 58-year-old man with chronic obstructive pulmonary disease is admitted with an acute exacerbation and hypercapnic respiratory failure (pH 7.25, PaCO₂ 70 mm Hg). He is drowsy but arousable. What is the most appropriate initial ventilatory support?AImmediate endotracheal intubation and invasive ventilationBTrial of non-invasive positive pressure ventilation if no contraindicationsCHigh-flow nasal oxygen onlyDSimple nasal prongs at 2 L/minEHeliox therapy onlyCheck my answer