A Case of Shy-Drager Syndrome Associated with Periodic Breathing

Abstract

A 45 year-old man with Shy-Drager syndrome was admitted to Chiba University Hospital for detailed examination of his sleep apnea, because he once had experienced respiratory arrest during sleep. There were no symptoms referrable to the respiratory system. Spirometry showed normal %VC and FEV1.0%. Paco₂ was normal at 38 Torr but there was mild hypoxemia (Pao₂; 72 Torr). Ventilatory responses to either CO₂ or hypoxia were preserved. In addition, the heart rate response to hypoxia was also preserved in this patient in whom autonomic function was impaired. However, the load compensation response to an artificially increased flow resistance was impaired when it was assessed by the ratio of the loaded to unloaded slope in the occlusion pressure response to CO₂.
He underwent overnight polysomnographic study and he exhibited abnormal breathing patterns. These were all found to be obstructive type and were mainly demonstrated to appear in stage 1 to 2 sleep with a periodic pattern of breathing, but they were not accompanied by severe arterial oxygen desaturation. The lowest Sao₂ during sleep was 83%.