Central sleep apnoea due to high-altitude periodic breathing

**Definition:** High-altitude periodic breathing is characterised by alternating periods of central apnoea and hyperpnoea associated with recent ascent to high altitude (typically > 2500 meters). The pattern of periodic breathing is an expected response to ascent to elevation. The disturbance is sufficiently severe to cause symptoms such as daytime sleepiness, disturbed sleep, awakening with dyspnoea, or snoring. The cycle length of this respiratory pattern is commonly less than 40 seconds and often as short as 12 to 20 seconds.

Note: This diagnosis can be made clinically based on symptoms and recent ascent to high altitude.