title: Impact of arousal threshold and respiratory effort on the duration of breathing events across sleep stage and time of night.
abstract: The frequency and duration of breathing events are influenced by sleep stage and time of day. In the present study we examined if these modifications are linked to adaptations in the arousal threshold and/or the magnitude of respiratory effort during and immediately after breathing events.
  
  
  
  Participants with sleep apnea slept for 3h in the evening and morning. For breathing events detected during these sessions the rate of change of respiratory effort, maximum respiratory effort immediately prior to termination of an event, and the maximum tidal volume and the minimum partial pressure of end-tidal carbon dioxide (PETCO2) immediately following an event were measured.
  
  
  
  The rate of change of respiratory effort was similar in N2 compared to N1 but the maximum respiratory effort immediately prior to event termination was greater (-10.7±1.2 vs. -9.6±1.0cmH2O/s, P<0.05). Likewise, tidal volume was increased (1169±105 vs. 1082±100ml, P<0.05) and PETCO2was decreased (37.0±0.8 vs. 37.7±0.8mmHg P<0.05) following events in N2 compared to N1. A similar tidal volume and PETCO2response was evident following events in the morning compared to the evening independent of sleep stage.
  
  
  
  We conclude that alterations in the arousal threshold, reflected by an increase in respiratory effort at event termination, coupled to increases in tidal volume and reductions in PETCO2contribute to modifications in event duration and frequency associated with variations in sleep state or time of night.
authors.affiliation: John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States.
authors.forename: Soheeb A
authors.initials: SA
authors.lastname: Wains
authors.affiliation: John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States.
authors.forename: Mohamad
authors.initials: M
authors.lastname: El-Chami
authors.affiliation: John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States; Department of Otolaryngology-Head & Neck Surgery, Wayne State University School of Medicine and Karmanos Cancer Institute, Detroit, MI 48201, United States.
authors.forename: Ho-Sheng
authors.initials: HS
authors.lastname: Lin
authors.affiliation: John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, United States. Electronic address: jmateika@med.wayne.edu.
authors.forename: Jason H
authors.initials: JH
authors.lastname: Mateika
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001143:Arousal / Q000502:physiology*; D002245:Carbon Dioxide / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D010313:Partial Pressure; D017286:Polysomnography; D012119:Respiration; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide
keywords: Carbon dioxide reserve; Chemoreflex sensitivity; Non-rapid eye movement sleep; Partial pressure of end-tidal carbon dioxide; Tidal volume