Central Sleep Apnea
What is Central Sleep Apnea?
Central Sleep Apnea is a sleep disorder characterized by pauses in breathing during sleep. It can be a congenital or acquired condition, and can also affect a patient's respiratory effort while awake.
Central Sleep Apnea differs from Obstructive Sleep Apnea which is characterized by a physical disruption of airflow in spite of respiratory effort. A Complex or Mixed sleep apnea exhibits characteristics of both central and obstructive sleep apnea.
When present from birth, central sleep apnea is called Congenital Central Hypoventilation Syndrome, CCHS, or historically, Ondine's Curse. Studies have it to be caused by a mutation of the PHOX2b gene.
CCHS is characterized by adequate ventilation while the patient is awake and by hypoventilation with shallow breathing during sleep. More severely affected patients hypoventilate when both awake and asleep. Both of these phenotypes present in the newborn period. Children with CCHS often have physiologic and anatomic manifestations of a generalized autonomic nervous system dysfunction, altered development of neural-crest-derived structures (i.e., Hirschsprung disease), and tumors.
Acquired central sleep apnea is usually the result of a brain stem stroke, tumor, or other injury which affects the ability of the brain to properly regulate respiratory drive.
Breathing Pacemakers for Central Sleep Apnea
The phrenic nerves are the pathways between the brain and the diaphragms which originate at C3 through C5. Injuries at or above C3 interrupt these pathways and render the patient dependent on ventilatory assistance. Immediately following injury, this assistance is provided by a mechanical ventilator. After the patient is stable, and cannot be weaned from mechanical ventilation, a breathing pacemaker can be considered.
A breathing pacemaker is a phrenic nerve stimulator which delivers electrical impulses to the diaphragms and restores breathing function. Pacing has many advantages over mechanical ventilation, including:
Breathing pacemakers provide respiratory function superior to mechanical ventilators since the inhaled air is drawn into the lungs by the diaphragm under negative pressure, rather than being forced into the chest under positive pressure.
Pacing patients experience lower infection rates due to the reduction in suctioning, elimination of external humidifier and ventilator circuits, and the potential removal of the tracheostomy tube.
Most patients prefer pacing over mechanical ventilation for a variety of reasons including normal breathing and speech patterns, ease of eating and drinking, and its silent operation.