HEART RATE VARIABILITY IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA-HYPOPNEA SYNDROME

Background. 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 disfunction. The gold standard for the treatment of OSAHS is ventilation with continuous positive airway pressure (CPAP). Aim: To study the effect of CPAP on autonomic disfunction in OSAHS patients, by assessing the heart rate variability (HRV) parameters before the initiation of CPAP and under CPAP during the first week and at 3 months. Materials and methods. We have assessed HRV parametrs by 24 hour ECG Holter monitoring in 42 patients with moderate and severe OSAHS (apneahypopnea index AHI = 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 and disscusion. Both the time and frequency domain HRV parameters decreased significantly during the first week of CPAP use (most of them below normal ranges) 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. Conclusions. Patients with OSAHS present a HRV alteration, 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, HRV parameters are normalized independently on disease severity.