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].