title: Characterizing the phenotypes of obstructive sleep apnea: clinical, sleep, and autonomic features of obstructive sleep apnea with and without hypoxia.
abstract: OBJECTIVE
  The pathophysiological basis of obstructive sleep apnea (OSA) is not completely understood and likely varies among patients. In this regard, some patients with OSA do not exhibit hypoxemia. We aimed to analyze the clinical, sleep, and autonomic features of a group of patients with severe OSA without hypoxia (OSA-h) and compare to OSA patients with hypoxia (OSA+h) and controls.
  
  
  METHODS
  Fifty-six patients with OSA-h, 64 patients with OSA+h, and 44 control subjects were studied. Clinical and sleep features were analyzed. Besides, time- and frequency-domain heart rate variability (HRV) measures comprising the mean R-R interval, the standard deviation of the RR intervals (SDNN), the low frequency (LF) oscillations, the high frequency (HF) oscillations, and the LF/HF ratio, were calculated across sleep stages during a one-night polysomnography.
  
  
  RESULTS
  OSA-h patients had a lower body mass index, a lower waist circumference, lower apnea duration, and a higher frequency of previous naso-pharyngeal surgery when compared to OSA+h patients. In terms of heart rate variability, OSA+h had increased LF oscillations (i.e., baroreflex function) during N1-N2 and rapid eye movement (REM) sleep when compared to OSA-h and controls. Both OSA+h and OSA-h groups had decreased HF oscillations (i.e., vagal inputs) during N1-N2, N3 and REM sleep when compared to controls. The LF/HF ratio was increased during N1-N2 and REM sleep, only in patients with OSA+h.
  
  
  CONCLUSIONS
  Patients with OSA-h exhibit distinctive clinical, sleep, and autonomic features when compared to OSA with hypoxia.
  
  
  CONCLUSIONS
  OSA is a heterogeneous entity. These differences must be taken into account in future studies when analyzing therapeutic approaches for sleep apnea patients.
authors.affiliation: Sleep Unit, Clinical Neurophysiology Section, University Clinic of Navarra, Pamplona, Spain; Dysautonomia Center, Department of Neurology, New York University Medical Center, New York, USA.
authors.forename: Jose-Alberto
authors.initials: JA
authors.lastname: Palma
authors.affiliation: Sleep Unit, Clinical Neurophysiology Section, University Clinic of Navarra, Pamplona, Spain. Electronic address: jiriarte@unav.es.
authors.forename: Jorge
authors.initials: J
authors.lastname: Iriarte
authors.affiliation: Department of Otoralyngology, University Clinic of Navarra, Pamplona, Spain.
authors.forename: Secundino
authors.initials: S
authors.lastname: Fernandez
authors.affiliation: Neurophysiology Laboratory, Neurosciences Area, CIMA, University of Navarra, Pamplona, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Valencia
authors.affiliation: Sleep Unit, Clinical Neurophysiology Section, University Clinic of Navarra, Pamplona, Spain; Neurophysiology Laboratory, Neurosciences Area, CIMA, University of Navarra, Pamplona, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Alegre
authors.affiliation: Sleep Unit, Clinical Neurophysiology Section, University Clinic of Navarra, Pamplona, Spain; Neurophysiology Laboratory, Neurosciences Area, CIMA, University of Navarra, Pamplona, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Artieda
authors.affiliation: Sleep Unit, Clinical Neurophysiology Section, University Clinic of Navarra, Pamplona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Urrestarazu
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D015992:Body Mass Index; D005260:Female; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010641:Phenotype; D017286:Polysomnography; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D012894:Sleep Stages
chemical_list: D010100:Oxygen
keywords: Autonomic nervous system; Cardiovascular function; Heart rate variability; Hypoxemia; Obstructive sleep apnea