Periodic Breathing

Periodic breathing is a cyclical breathing pattern where ventilation progressively increases (crescendo), then progressively decreases (decrescendo), often with brief pauses between cycles. The cycle length is typically 30 to 100 seconds. The most well-known form is Cheyne-Stokes respiration, associated with congestive heart failure.

Periodic breathing occurs when the brain's respiratory control feedback loop becomes unstable. Small changes in blood CO2 levels trigger disproportionate responses, creating an oscillating pattern. This can happen in heart failure (delayed circulatory time), at high altitude (reduced oxygen pressure), with certain medications (opioids), and during the transition from wakefulness to sleep.

On PAP therapy, periodic breathing may indicate treatment-emergent central sleep apnea or an underlying condition that requires specific treatment. Standard CPAP does not effectively treat periodic breathing. ASV (Adaptive Servo-Ventilation) is specifically designed to stabilise this pattern by providing variable pressure support that counters the oscillations.