title: Respiratory muscle activity and patient-ventilator asynchrony during different settings of noninvasive ventilation in stable hypercapnic COPD: does high inspiratory pressure lead to respiratory muscle unloading?
abstract: BACKGROUND
  High-intensity noninvasive ventilation (NIV) has been shown to improve outcomes in stable chronic obstructive pulmonary disease patients. However, there is insufficient knowledge about whether with this more controlled ventilatory mode optimal respiratory muscle unloading is provided without an increase in patient-ventilator asynchrony (PVA).
  
  
  METHODS
  Ten chronic obstructive pulmonary disease patients on home mechanical ventilation were included. Four different ventilatory settings were investigated in each patient in random order, each for 15 min, varying the inspiratory positive airway pressure and backup breathing frequency. With surface electromyography (EMG), activities of the intercostal muscles, diaphragm, and scalene muscles were determined. Furthermore, pressure tracings were derived simultaneously in order to assess PVA.
  
  
  RESULTS
  Compared to spontaneous breathing, the most pronounced decrease in EMG activity was achieved with the high-pressure settings. Adding a high breathing frequency did reduce EMG activity per breath, while the decrease in EMG activity over 1 min was comparable with the high-pressure, low-frequency setting. With high backup breathing frequencies less breaths were pressure supported (25% vs 97%). PVAs occurred more frequently with the low-frequency settings (P=0.017).
  
  
  CONCLUSIONS
  High-intensity NIV might provide optimal unloading of respiratory muscles, without undue increases in PVA.
authors.affiliation: Department of Pulmonary Diseases and Home Mechanical Ventilation, University Medical Centre Groningen.
authors.forename: Marieke L
authors.initials: ML
authors.lastname: Duiverman
authors.affiliation: Faculty of Medical Sciences, University of Groningen.
authors.forename: Anouk S
authors.initials: AS
authors.lastname: Huberts
authors.affiliation: Inbiolab B.V., Groningen, the Netherlands.
authors.forename: Leo A
authors.initials: LA
authors.lastname: van Eykern
authors.affiliation: Department of Pulmonary Diseases and Home Mechanical Ventilation, University Medical Centre Groningen.
authors.forename: Gerrie
authors.initials: G
authors.lastname: Bladder
authors.affiliation: Department of Pulmonary Diseases and Home Mechanical Ventilation, University Medical Centre Groningen.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Wijkstra
mesh_terms: D000368:Aged; D004576:Electromyography; D018575:Home Care Services, Hospital-Based; D006801:Humans; D006935:Hypercapnia / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D001239:Inhalation; D008168:Lung / Q000503:physiopathology*; D008875:Middle Aged; D009426:Netherlands; D063087:Noninvasive Ventilation / Q000009:adverse effects / Q000379:methods*; D011312:Pressure; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D012123:Pulmonary Ventilation; D012132:Respiratory Muscles / Q000503:physiopathology*; D013997:Time Factors; D016896:Treatment Outcome
keywords: chronic obstructive pulmonary disease; electromyography; high-intensity NIV; ineffective efforts