A 71-year-old male with chronic bronchitis and obstructive emphysema for nearly 10 years, previously resuscitated twice for respiratory failure. Currently experiences dyspnea on exertion, with arterial blood gas (ABG) showing PaO₂ < 6.7 kPa (50 mmHg) and PaCO₂ 6.7 kPa (50 mmHg) without oxygen. Under physician-guided respiratory rehabilitation. To alleviate pulmonary hypertension and improve quality of life, which treatment is preferred?