title: Acute effects of autoadjusting and fixed continuous positive airway pressure treatments on cardiorespiratory coupling in obese patients with obstructive sleep apnea.
abstract: BACKGROUND
  Treatment with positive airway pressure devices improved signs and symptoms of obstructive sleep apnea syndrome (OSA); however, auto-adjusting positive pressure (APAP) device was not as effective as continuous positive airway pressure (CPAP) in reducing arterial blood pressure and insulin resistance. The role played by autonomic cardiac regulation remains to be clarified. We aimed to test the effects of CPAP and APAP on autonomic regulation and cardiorespiratory coupling during sleep.
  
  
  METHODS
  We retrospectively analyzed full-night polysomnographic studies. 19 patients newly diagnosed with severe OSA (AHI>30) and 7 obese subjects without OSA (CON) were enrolled. Each OSA subject was assigned to CPAP or APAP treatment and underwent a sleep study after 1 week of treatment. Spectral and cross-spectral analyses of heart rate variability (HRV) and respiration were performed to assess autonomic profile and coherence (K2) between respiration and HF oscillation during sleep in CPAP, APAP and CON groups.
  
  
  RESULTS
  In CPAP and CON, LFnu and LF/HF, markers of sympathetic modulation, decreased from N2 to N3 and increased during REM sleep (p<0.001), while in APAP group, sympathetic modulation was significantly higher compared with those of CPAP and CON during all sleep stages. K2 values were lower in APAP compared with those in CPAP and CON.
  
  
  CONCLUSIONS
  APAP treatment was characterized by a greater sympathetic activation and it was associated with a lower cardio-respiratory coupling compared with CPAP. This might account for the different effects on cardiovascular risk factors induced by the two treatments.
authors.affiliation: Department of Biomedical and Clinical Sciences, University of Milan, Division of Medicine and Pathophysiology, L. Sacco Hospital, Milan, Italy; Division of Pulmonary Rehabilitation, I.M.F.R., Udine, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Patruno
authors.affiliation: Department of Biomedical and Clinical Sciences, University of Milan, Division of Medicine and Pathophysiology, L. Sacco Hospital, Milan, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Tobaldini
authors.affiliation: Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Bianchi
authors.affiliation: Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy; Faculty of Sciences, Autonomous University of San Luis Potosi, Mexico.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Mendez
authors.affiliation: Division of Pulmonary Rehabilitation, I.M.F.R., Udine, Italy.
authors.forename: Orietta
authors.initials: O
authors.lastname: Coletti
authors.affiliation: Department of Biomedical and Clinical Sciences, University of Milan, Division of Medicine and Pathophysiology, L. Sacco Hospital, Milan, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Costantino
authors.affiliation: Department of Biomedical and Clinical Sciences, University of Milan, Division of Medicine and Pathophysiology, L. Sacco Hospital, Milan, Italy. Electronic address: nicola.montano@unimi.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Montano
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System; D016022:Case-Control Studies; D015331:Cohort Studies; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D017286:Polysomnography; D011175:Positive-Pressure Respiration / Q000379:methods; D012119:Respiration; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000628:therapy*
keywords: Autonomic nervous system; Continuous positive airway pressure; Heart rate variability; Obstructive sleep apnea; Sleep; Sympathovagal balance