Cheyne-Stokes breathing

The cycle reflects a delay between PaCO2 changes at the alveolus and the central chemoreceptors: hyperventilation overshoots and drops PaCO2 below the apneic threshold, breathing stops, CO2 rises, hyperpnea resumes — and the loop repeats. It is common in CHF (prolonged circulation time exaggerates the delay), large strokes affecting bilateral cerebral hemispheres or upper brainstem, high altitude, and uremia, and in the dying patient ('agonal breathing'). Distinguish from Kussmaul breathing (deep, regular hyperpnea in metabolic acidosis, e.g., DKA), Biot breathing (cluster breathing with abrupt apneas, medullary lesions), and apneustic breathing (prolonged inspiratory pauses, pontine lesions). Treatment in CHF is optimization of heart failure; some patients respond to nocturnal oxygen or adaptive servo-ventilation (cautiously, given the SERVE-HF concerns).