FIG. 35:  The polysomnographic features of TE-CSA are also variable.  The commonest feature is the non-CSR pattern of CSA.^[1,30]  As shown in this Figure, the central apneas are cyclical, but there is an abrupt transition from apneas to hyperpneas, unlike the smooth waxing and waning that is seen in CSR.  Other subtle polysomnographic features include arousals that occur at apnea termination, which contrasts with the arousals that occur during hyperpnea in CSR.  Finally, TE-CSA has been noted to be worse in supine versus non-supine sleep. 

In all of these presentations OSA is the underlying SBD, and the CSA is provoked by treatment of the OSA.  OSA is typically very responsive to PAP therapy, but residual obstructive events may occur and co-exist with central apneas during the titrations.  When these central apneas exist, decreased inspiratory efforts may occur during obstructive events, and as a result the obstructive events endure longer than expected and therefore may be associated with worse hypoxemia.