CENTRAL & OBSTRUCTIVE SLEEP APNEA (CSA & OSA)
Pathophysiological background of the diseases
In central sleep apnea (CSA) a dysfunctional respiratory drive results in apnea events during sleep. These events appear periodically together with phases of hyperventilation. CSA is common in patients with heart failure. OSA is a sleep disorder characterized by recurrent episodes of cessation of airflow, with or without partial or complete upper airway obstruction during sleep, leading to disruptions in normal breathing patterns. The obstruction results in intermittent hypoxia and hypercapnia, as well as sleep fragmentation. OSA is primarily caused by anatomical and physiological factors that contribute to airway collapse, such as obesity, anatomical abnormalities, and decreased upper airway muscle tone. Newer data also suggest a pathomechanism in OSA that is dependent on respiratory drive [73]. The repetitive episodes of hypoxia and hypercapnia trigger physiological responses, including sympathetic activation, systemic inflammation, oxidative stress, and endothelial dysfunction [74]. These responses contribute to the development of neurocognitive, cardiovascular and metabolic comorbidities commonly associated with OSA, such as daytime sleepiness, hypertension, coronary artery disease, and insulin resistance [75].