Treatment-emergent central sleep apnoea after surgery for obstructive sleep apnoea

Central sleep apnoea (CSA) is a lack of drive to breathe during sleep, which can occur in physiologic as well as in pathologic conditions. A particular type of CSA, defined treatment-emergent CSA (TECSA), may occur after the treatment of obstructive sleep apnoea syndrome (OSAS), either with CPAP or surgery. TECSA is transitory and seems to be related to the severity of OSAS. We describe a 51-year-old man affected by severe OSAS who developed severe, transient CSA immediately after upper airways surgery. We believe that CSA was triggered by the sudden variation in nocturnal arterial PCO2, which decreased from 52.3 mmHg before surgery to 42.0 mmHg after surgery. It is conceivable that, due to long-lasting severe OSAS, our patient lowered his chemosensitivity to PCO2. Consequently, the resolution of obstructive apnoeas and the restoration of normal nocturnal values of PCO2 may have reduced the nocturnal PCO2 to the point of being inadequate to stimulate ventilation.