We thank you very much for the interesting questions about our article.

In the group of patients with CSA/CSR (40.6% of the total patients) the diagnosis was made in the beginning, with a polissonography.

In the group with CompSAS, the diagnosis was made in patients who presented central sleep apnea after starting treatment with autoCPAP/CPAP for obstructive sleep apnea. These patients maintained a high AHI despite treatment (more than 2–3 months after the beginning of the treatment) so they were submitted to a split-night study about 4 months after the initial sleep study.

All the patients were submitted to a split night study and in all of the patients the technician always try first the treatment with PAP (CPAP/AutoCPAP/BIPAP) but because it did not resolved the central apnea, the technician switched to servoventilation, with excellent results.1,2

Only one patient was treated with BIPAP (S/T mode). The first pressures were 18/14 but the patient suddenly died and we had no time to optimize the best pressures for him.

As the study is retrospective, not all the patients had previously realized echocardiogram before PAP therapy so the comparison between the two ventilatory modes concerning cardiac function cannot be made with confidence and we have declared this fact as a limitation of the study.

The authors of the letter say that in the present study no differences were encountered in terms of cardiovascular (CV) mortality but this is not what we demonstrated: there was no difference in terms of non-fatal cardiovascular events (3 events in each group) but in PAP group 2 patients died of sudden death.