An 80-year-old man with severe central sleep apnea due to Cheyne-Stokes breathing (AHI 41.2) caused by severe cardiac failure underwent a trial of adaptive servo-ventilation (ASV) by full face mask after failure of a fixed CPAP trial. Recommended procedure was closely followed and the ASV device activated normally during central apneas. Initial settings were EEP 5, PSmin 3, PSmax 15 on room air. The device did not capture the thorax or abdomen, as shown by lack of change in respiratory inductive plethysmography, despite expected mask pressure waveforms. Snoring was also detected during apneas with device activation. Desaturation continued, followed by arousals during hyperpnea. On the device, the patient clearly slept for 1-3 epochs during the central apneas only to awaken during hyperpnea. We hypothesize that the failure to capture may have resulted from "reverse" obstructive apnea, possibly due to glottic closure during ASV activation. We suggest that earlier manual adjustments to ASV in cases such as ours, prior to waiting for the recommended 20 to 40 min of sleep, may be appropriate in selected patients. We also consider additional interventions that may increase the likelihood of a successful trial.