Central Sleep Apnea (CSA)

DefinitionTop

Central sleep apnea (CSA) is characterized by episodes of cessation of breathing due to decreased activity of the respiratory center or impaired transmission of impulses from nerves to respiratory muscles. It can be associated with hyperventilation/hypocapnia or hypoventilation/hypercapnia. On polysomnography, CSA is diagnosed when the central apnea and/or central hypopnea index is ≥5 per hour and if the total number of central events is >50% of the total apneas and hypopneas. There are additional diagnostic criteria for the specific types of CSA (see below) as outlined by the third edition of the International Classification of Sleep Disorders (ICSD-3).

Clinical FeaturesTop

Types of CSA in adults from the ICSD-3:

1) CSA with Cheyne-Stokes breathing (CSB): Pulmonary congestion in patients with heart failure (HF) causes hyperventilation, which results in hypocapnia and subsequent apnea. For the ventilation pattern to meet the criteria for CSB, there must be ≥3 consecutive central apneas and/or hypopneas separated by crescendo-decrescendo breathing with a cycle length of ≥40 seconds. The prevalence is ~30% in patients with HF; CSB may be associated with increased morbidity and mortality. Apart from HF, CSB is associated with atrial fibrillation/flutter, renal failure, or neurologic disorders (eg, following stroke).

2) CSA due to a medical disorder without CSB occurs in cardiac, renal, and neurologic disorders, but without a CSB pattern.

3) CSA due to high-altitude periodic breathing: Hyperventilation occurs in response to hypoxia at high altitude (typically ≥2500 m), resulting in hypocapnia and secondary cessation of breathing.

4) CSA due to a medication or substance is most frequently caused by chronic use of long-acting opioids. It is accompanied by hypercapnia.

5) Primary CSA: Rare hypocapnic form of CSA of unknown cause, also referred to as idiopathic CSA.

6) Treatment-emergent CSA (previously called complex sleep apnea): CSA that develops in patients with obstructive sleep apnea (OSA) upon initiation of positive airway pressure (PAP) therapy. It resolves in the majority of individuals after 3 months of PAP usage.

TreatmentTop

Treatment depends on the cause of CSA and includes:

1) Optimization of HF treatment.

2) Positive airway pressure: Continuous positive airway pressure (CPAP) targeted to normalize the apnea-hypopnea index (AHI). Adaptive servoventilation (ASV) should not be used in patients with HF with left ventricular ejection fraction (LVEF) ≤45% due to increased total and cardiovascular mortality.Evidence 1Strong recommendation (downsides clearly outweigh benefits; right action for all or almost all patients). High Quality of Evidence (high confidence that we know true effects of the intervention). Cowie MR, Woehrle H, Wegscheider K, et al. Adaptive Servo-Ventilation for Central Sleep Apnea in Systolic Heart Failure. N Engl J Med. 2015 Sep 17;373(12):1095-105. doi: 10.1056/NEJMoa1506459. Epub 2015 Sep 1. PMID: 26323938; PMCID: PMC4779593. Bilevel positive airway pressure (BiPAP) in spontaneous-timed (ST) mode with a back-up rate can be considered, but it has similar physiologic effects and therefore potentially similar risks as ASV in this HF population.

3) Nocturnal supplemental oxygen.

4) Transvenous phrenic nerve stimulation.

5) Acetazolamide in primary CSA and high-altitude periodic breathing.

6) BiPAP-ST ventilation in patients with CSA related to hypoventilation.

7) ASV in patients with treatment-emergent CSA.