This chapter discusses the diagnosis, evaluation and management of chronic obstructive pulmonary disease (COPD). Airflow restriction may be severe, leading to patients presenting in an upright or tripod position, with cyanosis, altered mental status, and respiratory arrest. Patients should be placed on supplemental oxygen therapy as needed to maintain adequate oxygen saturations of 88-92%. Over-oxygenating the COPD patient can lead to worsening ventilation-perfusion mismatch and apnea. Patients must be monitored for signs of impending respiratory failure. CPAP and BiPAP may be considered for certain patients with moderate to severe COPD exacerbations. The goal of ventilator management in the COPD patient is to oxygenate and ventilate without causing barotrauma and hemodynamic instability. If patients acutely decompensate while receiving invasive or noninvasive positive pressure ventilation, the possibility of pneumothorax and intrinsic positive end-expiratory pressure (auto-PEEP) should be considered.