Figure 2From: Fit for high altitude: are hypoxic challenge tests useful?Idoneità all’alta montagna: i test all’ipossia sono davvero utili?Polysomnography of a copd patient breathing 2 l/min nasal air at night. The patient shows a poor sleep quality due to frequent awakenings, and continuous hypercapnic (transcutaneous PCO2), hypoxic (transcutaneous PO2) and pulmonary hypertension (mean pulmonary artery pressure, Pap, m) recordings.Back to article page