Sleep-related respiratory disorders in heart failure patients: prevalence,pathophysiology and treatment

Cheyne-Stokes respiration occurs during sleep in 40-45 % of patients with N YHA class III and IV heart failure. Such patients experience repeated episo des of progressively diminishing ventilation associated with desaturation f ollowed by periods of increasing-amplitude ventilation. The mechanism appears to be related to hyperventilation leading to hypocapn ia which occurs near a critical threshold of apnea during sleep stages I an d stage II and interrupts central ventilatory control. The total duration o f the periodic respiration cycle would depend an the increased circulation time subsequent to lowered cardiac output. Brief periods of waking provoked by Cheyne-Stokes respiration, accentuating sympathetic nervous system activity, are an unfavorable prognostic factor in heart failure. Activation of the sympathetic system may be corrected by CPAP although the long-term effect on heart failure remains controversial. Other treatments, such as oxygen therapy or theophylline, combined with opt imized treatment of heart failure, have been proposed.