Central sleep apnoea (CSA) can be divided into hypercapnic (due to hypoventilation disorders) and hypocapnic (due to hyperventilaton disorders).The hypocapnic type is commonly seen in congestive heart failure (CHF) where it is also known as Cheyne-Stokes respiration.This type of central apnoea is characterized by a waxing and waning ventilation pattern, usually in stages 1 & 2 nonREM sleep, triggered by arousal, worse when supine and associated with an elevated minute volume of ventilation.