Figure 3.

The same copd patient as in figure 2 breathing 2 l/min supplemental nasal O₂ at night. Sleep quality and pulmonary hypertension are improved, arterial hypoxemia is normalized with unchanged hypercapnia. This patient could tolerate a 7 hour flight breathing 4 L/min nasal O₂ at rest in a commercial aircraft with a cabin pressure equivalent to an altitude of 2,500 m without additional mechanical ventilatory support.