title: Heart rate variability evaluation of Emfit sleep mattress breathing categories in NREM sleep.
abstract: OBJECTIVE
  Heart rate variability (HRV) analysis of obstructive sleep apnea patients reveals an increase in sympathetic activity. Sleep disordered breathing (SDB) can be also assessed with sleep mattress sensors, as the Emfit sensor, by dividing the signal into different breathing categories. In addition to normal breathing (NB) and periodic apneas/hypopneas (POB), the sleep mattress unveils a breathing category consisting of sustained partial obstruction (increased respiratory resistance, IRR). The aim of our study was to evaluate HRV during these three breathing categories in NREM sleep.
  
  
  METHODS
  53 patients with suspected SDB underwent an overnight polysomnography with an Emfit mattress. The Emfit signal was scored in 3-min epochs according to the established rules. The NB, POB, and IRR epochs were combined to as long NB, POB and IRR periods as possible and HRV was calculated from at least 6-min epochs.
  
  
  RESULTS
  The meanHR did not differ between the breathing categories. HRV parameters revealed an increase in sympathetic activity during POB. The mean LF/HF ratio was highest during POB (3.0) and lowest during IRR (1.3). During NB it was 1.7 (all p-values ⩽ 0.001). Interestingly sympathetic activity decreased and parasympathetic activity increased during IRR as compared to NB (the mean HF power was 1113.8 ms(2) during IRR and 928.4 ms(2) during NB).
  
  
  CONCLUSIONS
  The HRV findings during POB resembled HRV results of sleep apnea patients but during sustained prolonged partial obstruction a shift towards parasympathetic activity was achieved.
  
  
  CONCLUSIONS
  The findings encourage the use of sleep mattresses in SDB diagnostics. In addition the findings suggest that sustained partial obstruction represents its own SDB entity.
authors.affiliation: Department of Clinical Neurophysiology, Tampere University Hospital, Medical Imaging Centre and Hospital Pharmacy, Pirkanmaa Hospital District, Tampere, Finland; Department of Electronics and Communication Engineering and BioMediTech, Tampere University of Technology, Tampere, Finland. Electronic address: mirja.tenhunen@pshp.fi.
authors.forename: Mirja
authors.initials: M
authors.lastname: Tenhunen
authors.affiliation: Department of Electronics and Communication Engineering and BioMediTech, Tampere University of Technology, Tampere, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Hyttinen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
authors.forename: Jukka A
authors.initials: JA
authors.lastname: Lipponen
authors.affiliation: Department of Clinical Neurophysiology, Tampere University Hospital, Medical Imaging Centre and Hospital Pharmacy, Pirkanmaa Hospital District, Tampere, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Virkkala
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Sonja
authors.initials: S
authors.lastname: Kuusimäki
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mika P
authors.initials: MP
authors.lastname: Tarvainen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
authors.forename: Pasi A
authors.initials: PA
authors.lastname: Karjalainen
authors.affiliation: Department of Clinical Neurophysiology, Tampere University Hospital, Medical Imaging Centre and Hospital Pharmacy, Pirkanmaa Hospital District, Tampere, Finland; School of Medicine, University of Tampere, Tampere, Finland.
authors.forename: Sari-Leena
authors.initials: SL
authors.lastname: Himanen
mesh_terms: D000328:Adult; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000503:physiopathology*; D012894:Sleep Stages
keywords: Emfit sensor; Flow limitation; Heart rate variability; Sleep; Sleep mattress sensors; Sleep-disordered breathing