title: Changes in the heart rate variability in patients with obstructive sleep apnea and its response to acute CPAP treatment.
abstract: BACKGROUND
  Obstructive Sleep Apnea (OSA) is a major risk factor for cardiovascular disease. The goal of this study was to demonstrate whether the use of CPAP produces significant changes in the heart rate or in the heart rate variability of patients with OSA in the first night of treatment and whether gender and obesity play a role in these differences.
  
  
  METHODS
  Single-center transversal study including patients with severe OSA corrected with CPAP. Only patients with total correction after CPAP were included. Patients underwent two sleep studies on consecutive nights: the first night a basal study, and the second with CPAP. We also analyzed the heart rate changes and their relationship with CPAP treatment, sleep stages, sex and body mass index. Twenty-minute segments of the ECG were selected from the sleep periods of REM, no-REM and awake. Heart rate (HR) and heart rate variability (HRV) were studied by comparing the R-R interval in the different conditions. We also compared samples from the basal study and CPAP nights.
  
  
  RESULTS
  39 patients (15 females, 24 males) were studied. The mean age was 50.67 years old, the mean AHI was 48.54, and mean body mass index was 33.41 kg/m(2) (31.83 males, 35.95 females). Our results showed that HRV (SDNN) decreased after the use of CPAP during the first night of treatment, especially in non-REM sleep. Gender and obesity did not have any influence on our results.
  
  
  CONCLUSIONS
  These findings support that cardiac variability improves as an acute effect, independently of gender or weight, in the first night of CPAP use in severe OSA patients, supporting the idea of continuous use and emphasizing that noncompliance of CPAP treatment should be avoided even if it is just once.
authors.affiliation: Clinical Neurophysiology Service, University Clinic of Navarra, Pamplona, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Kufoy
authors.forename: Jose-Alberto
authors.initials: JA
authors.lastname: Palma
authors.forename: Jon
authors.initials: J
authors.lastname: Lopez
authors.forename: Manuel
authors.initials: M
authors.lastname: Alegre
authors.forename: Elena
authors.initials: E
authors.lastname: Urrestarazu
authors.forename: Julio
authors.initials: J
authors.lastname: Artieda
authors.forename: Jorge
authors.initials: J
authors.lastname: Iriarte
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D045422:Continuous Positive Airway Pressure; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000503:physiopathology; D010349:Patient Compliance; D017286:Polysomnography; D012189:Retrospective Studies; D012307:Risk Factors; D012727:Sex Characteristics; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D012894:Sleep Stages / Q000502:physiology; D013564:Sympathetic Nervous System / Q000503:physiopathology