[Variability of cardiac rate in patients with obstructive sleep apnea/hypopnea]

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by repeated breathing pauses caused by upper airway collapse during sleep, leading to intermittent hypoxemia, sleep fragmentation and autonomic dysfunction. The gold standard for the treatment of OSAHS is ventilation with continuous positive airway pressure (CPAP).

To study the effect of CPAP on autonomic dysfunction in patients OSAHS, by assessing the heart rate variability (HRV) parameters before the initiation of CPAP and under CPAP during the first week and at 3 months.

We have assessed HRV parametrs by 24 hours ECG Holter monitoring in 42 patients with moderate and severe OSAHS (apnea-hypopnea index AHI > or = 15/h) without other causes of autonomic neuropathy. The assessment was made at diagnosis, during the first week of CPAP use and at 3 months of CPAP use. RESULTS. Both time domain and frequency domain HRV parameters decreased significantly during the first week of CPAP use and increased back to normal values at 3 months. Initially and during the first week of treatment, HRV parameters correlated negatively with the severity of OSAHS expressed by AHI.

Patients with OSAHS present an alteration of HRV, proportionally with disease severity. The decrease in HRV is revealed by the absence of apneas during the initiation of CPAP. After 3 months of CPAP treatment, the HRV parmeters are normalized independently of the disease severity.