Nocturnal desaturations in COPD: still an open question?

The relevance of sleep oxyhemoglobin desaturations in COPD patients is still a matter of debate. The best definition for clinical outcomes is the occurrence of episodes lasting at least 5 minutes and reaching SaO2 levels less than or equal to 85%. Focusing on longer and milder episodes (at least 30% of the night with SaO2 < 90%) did not provide clinical relevance. One possible consequence of desaturation episodes could be a worsening of pulmonary hemodynamics, but O2 dips could just be a marker of a mechanical derangement associated with a worse prognosis. Data confirming the association of these episodes with the clinical type of COPD and with inflammatory mediator modulation are still lacking.