Polysomnographic findings in congenital central hypoventilation syndrome (CCHS)

This tracing from a 2.5-year-old girl shows the typical breathing pattern during NREM (stage N) sleep in congenital central hypoventilation syndrome (CCHS). Note the regular shallow breathing. The tidal volume is abnormally low, at 2.9 cc/kg (normal is approximately 5-6 cc/kg), and respiratory rate is stable at 22 breaths/minute, resulting in a minute ventilation of only 64 cc/kg/minute. The patient also displays hypercapnia (end-tidal PaCO₂ is 71 mmHg; normal is <50) and hypoxemia (SaO₂ 69%; normal is >95%). The failure of hypoxemia and hypercapnia to stimulate ventilation and/or arousal during sleep is diagnostic of a central control of breathing disorder and characteristic of CCHS. Decreased heart rate variability, characteristic of CCHS, is also present.