Cheyne-Stokes Respiration (CSR) is form of sleep apnea marked by an abnormal breathing cycle cycle of rapid, shallow breaths, long-winded sighs, and ceasation of breathing (apnea). The hyperventilation drops the body's CO2 below the "apneic threshhold". Breathing stops, the CO2 level rises, and breathing begins once again. The suspected reason for this is because fluctuations in CO2 and O2 levels are picked up too late by the mechanism responsible for unconscious breathing, causing the body to overcompenstate and "play catch-up". In rare cases Cheyne-Stokes respiration results in hypoxia, but the most significant effect is the disruption of sleep, as the inflicted will suffer frequent wakings due to feelings of suffocation. The most common sufferers are people with congestive heart failure, but CSR is also found in patients with neurological disorders and in infants. Diagnosis of CSR is done with an overnight polysomnography, and is treated with the prescription drug aminophylline or a CPAP device.
Cheyne-Stokes respiration is also prevalent in high altitude climbers, but is considered normal above 10,000 feet and relatively benign unless accompanied by illness or injury. Because of its tendency to wear the climber out, acetazolamide is often taken prior to ascent to prevent the onset of CSR.
The condition was named after John Cheyne and William Stokes, the physicians who first classified it.