This CPB is revised to state that oxygen for cluster headaches is considered medically necessary that meet the diagnostic criteria used by the International Headache Society to form a definitive diagnosis of cluster headache, where the headaches are refractory to prescription medications. This CPB is revised to state that oxygen therapy is considered not medically necessary for the following indications: angina pectoris in the absence of hypoxemia; dyspnea without cor pulmonale or evidence of hypoxemia; severe peripheral vascular disease resulting in clinically evident desaturation in one or more extremities but in the absence of systemic hypoxemia; and terminal illnesses that do not affect the respiratory system. Qualifying lab values for oxygen are revised to be consistent with current Medicare DME MAC criteria. This CPB is revised to state that preset portable oxygen units are considered not medically necessary.