title: Pulse wave amplitude reduction: a surrogate marker of micro-arousals associated with respiratory events occurring under non-invasive ventilation?
abstract: BACKGROUND
  Respiratory events occurring under non-invasive ventilation (NIV) may produce sleep fragmentation. Alternatives to polysomnography (PSG) should be validated for providing simple monitoring tools for patients treated at home with NIV.
  
  
  OBJECTIVE
  To study the value of pulse wave amplitude (PWA) reduction as a surrogate marker of cortical micro-arousals associated with respiratory events occurring during NIV.
  
  
  METHODS
  27 PSG tracings under NIV recorded in 9 stable patients with Obesity Hypoventilation Syndrome (OHS), under 3 different ventilator modes (no back-up rate, low or high back-up rate) were analyzed. For all respiratory events (obstructive, central, or mixed event), the association with EEG-micro-arousals, PWA reduction of more than 30% and the presence of associated SpO2 desaturation ≥ 4% was recorded.
  
  
  RESULTS
  2474 respiratory events during NREM sleep were analyzed. 73.6% were associated with an EEG-MA, 91.4% with a ≥ 4% decrease in SpO2, and 74.9% with a significant PWA reduction. Sensitivity of PWA for the detection of an EEG-micro-arousal related to a respiratory event was 89.1% [95%CI: 76.7-95.3]. Positive predictive value (PPV) was 87.0% [95%CI: 75.0-94.0]. Sensitivity of PWA was highest in the S mode, compared to both other S/T modes, p = <0.001. Sensitivity of PWA was also higher for central and mixed events, compared to obstructive respiratory events, p = <0.05.
  
  
  CONCLUSIONS
  PWA reduction is a sensitive marker with a high PPV for the detection of EEG-MA associated with respiratory events during NREM sleep in stable OHS patients treated by NIV. In this situation, PWA could be used to improve scoring of hypopneas and allow an appropriate assessment of sleep fragmentation related to respiratory events.
authors.affiliation: Division of Pulmonary Diseases, Geneva University Hospitals, 1211 Geneva 14, Switzerland; Sleep Laboratory, Department of Psychiatry, Geneva University Hospitals, 1211 Geneva 14, Switzerland. Electronic address: dan.adler@hcuge.ch.
authors.forename: Dan
authors.initials: D
authors.lastname: Adler
authors.forename: Pierre Olivier
authors.initials: PO
authors.lastname: Bridevaux
authors.forename: Olivier
authors.initials: O
authors.lastname: Contal
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Georges
authors.forename: Elise
authors.initials: E
authors.lastname: Dupuis-Lozeron
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Claudel
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Pépin
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Janssens
mesh_terms: D001143:Arousal / Q000502:physiology*; D004569:Electroencephalography; D006801:Humans; D008875:Middle Aged; D063087:Noninvasive Ventilation; D010845:Obesity Hypoventilation Syndrome / Q000503:physiopathology* / Q000628:therapy; D017286:Polysomnography; D063177:Pulse Wave Analysis; D012890:Sleep / Q000502:physiology*
keywords: Chronic respiratory insufficiency; Micro-arousals; Monitoring; Non-invasive ventilation; Polysomnography; Pulse wave amplitude