Central Sleep Apnea
Patients with central sleep apnea fall into 2 groups based on their carbon dioxide level and ventilatory drive.
Cheyne-Stokes breathing, a discrete pattern of the second form of central sleep apnea, is thought to be caused by intrinsic properties of the respiratory control center in the response to hypoxia and acidosis with hyperpnea, causing reoxygenation and alkalosis, leading to hypoventilation by hypopnea and apnea.
Central sleep apnea occurs at high altitude in healthy people as a consequence of hypobaric hypoxia.
Congenital central hypoventilation (a form of Ondine curse) is a rare form of idiopathic CSA in neonates and may be associated with Hirschsprung disease. A mutation in the PHOX2 gene is responsible for 80 to 90% of cases. This mutation produces variable phenotypes, and clinically evident cases are inherited in a dominant pattern.
Central sleep apnea is usually asymptomatic and is detected by caretakers or bed partners who notice long respiratory pauses, shallow breaths, or restless sleep. Patients with hypercapnic forms may experience daytime somnolence (sometimes called wake-time sleepiness), lethargy, and morning headache.
Diagnosis of central sleep apnea is suspected on the basis of history and is confirmed by polysomnography. However, testing may not be necessary if there are no symptoms and a treatable medical disorder that can cause sleep apnea (eg, heart failure) can be addressed. To diagnose central nervous system causes of CSA, brain or brain stem imaging may be indicated.
Primary treatment of central sleep apnea is optimal management of underlying disorders and avoidance of opioids and other sedatives. Secondary treatment of symptomatic patients can be a trial of supplemental oxygen or, in patients with hypercapnic CSA who have symptoms despite other treatments, noninvasive continuous or bilevel positive airway pressure.
For patients who have CSA and Cheyne-Stokes breathing, continuous positive airway pressure or supplemental oxygen may decrease apneic and hypopneic episodes, but effects on clinical outcomes are not clear. Acetazolamide is effective in central sleep apnea caused by high altitude.
Electrode pacing of the phrenic nerve and/or diaphragm is an option, such as for children > 2 years with congenital central hypoventilation syndrome.
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