Cheyne-stokes respiration

CSA-CSR is a disorder characterized by cyclic hyperventilation with hypocapnia, triggered by the state change or arousal commonly seen in advanced HF of all causes. Snoring may occur during the peak of ventilation. The AHI is a crude marker of CSA-CSR severity and consideration should always be given to collateral history and examination, plus markers of cardiac and sleep dysfunction, plus quality of life when deciding whether to monitor or to manage. Loop gain (a ratio of ventilation to corresponding apnea) may be an alternative objective marker of CSA-CSR severity. Positive airway pressure is a treatment option that assists cardiac function and improves oxygen delivery, and is unique to CSA-CSR. In contrast, CPAP in OSA has its major role in upper airway stabilization, as indicated by a decrease in AHI to negligible levels.