Evaluation of respiratory center function in congenital central hypoventilation syndrome by monitoring electrical activity of the diaphragm

Abstract

Background: A definitive diagnosis of congenital central hypoventilation syndrome (CCHS) is made by genetic testing. However, there are only a few examinations that warrant genetic testing. Electrical activity of the diaphragm (Edi) reflects neural respiratory drive from respiratory center to diaphragm. We evaluated the function of the respiratory center in CCHS by Edi monitoring.

Methods: Monitoring of Edi was performed in six CCHS cases without mechanical ventilation. The monitoring time was 30 consecutive minutes from wakefulness to sleep. The TcPCO₂ or EtCO₂ and SpO₂ were recorded simultaneously.

Results: The Edi peak during wakefulness was 14.0 (10.3-21.0) µV and the Edi peak during sleep was 6.7 (3.8-8.0) µV. The Edi peak during sleep was significantly lower than the Edi peak during wakefulness, and patients were in a state of hypoventilation. Although TcPCO₂ or EtCO₂ increased due to hypoventilation, an increase in the Edi peak that reflects central respiratory drive was not observed. ΔEdi/ΔCO₂ was -0.06μV/mmHg. Maximum EtCO₂ or TcPco₂ was 51 mmHg, and the average SpO₂ was 91.5% during monitoring.

Conclusions: We confirmed that Edi monitoring could evaluate the function of the respiratory center and reproduce the hypoventilation of CCHS. The present study suggested that Edi monitoring is a useful examination in deciding whether to perform genetic testing or not and it may lead to an early diagnosis of CCHS.

Keywords: congenital central hypoventilation syndrome; diagnostic method; early diagnosis; electrical activity of diaphragm; respiratory center function.