title: Patient-Ventilator Interaction During Noninvasive Ventilation in Simulated COPD.
abstract: BACKGROUND
  During noninvasive ventilation (NIV) of COPD patients, delayed off-cycling of pressure support can cause patient ventilator mismatch and NIV failure. This systematic experimental study analyzes the effects of varying cycling criteria on patient-ventilator interaction.
  
  
  METHODS
  A lung simulator with COPD settings was connected to an ICU ventilator via helmet or face mask. Cycling was varied between 10 and 70% of peak inspiratory flow at different breathing frequencies (15 and 30 breaths/min) and pressure support levels (5 and 15 cm H2O) using the ventilator's invasive and NIV mode with and without an applied leakage.
  
  
  RESULTS
  Low cycling criteria led to severe expiratory cycle latency. Augmenting off-cycling reduced expiratory cycle latency (P < .001), decreased intrinsic PEEP, and avoided non-supported breaths. Setting cycling to 50% of peak inspiratory flow achieved best synchronization. Overall, using the helmet interface increased expiratory cycle latency in almost all settings (P < .001). Augmenting cycling from 10 to 40% progressively decreased expiratory pressure load (P < .001). NIV mode decreased expiratory cycle latency compared with the invasive mode (P < .001).
  
  
  CONCLUSIONS
  Augmenting the cycling criterion above the default setting (20-30% peak inspiratory flow) improved patient ventilator synchrony in a simulated COPD model. This suggests that an individual approach to cycling should be considered, since interface, level of pressure support, breathing frequency, and leakage influence patient-ventilator interaction and thus need to be considered.
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany. omoerer@med.uni-goettingen.de.
authors.forename: Onnen
authors.initials: O
authors.lastname: Moerer
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany.
authors.forename: Lars-Olav
authors.initials: LO
authors.lastname: Harnisch
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Herrmann
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Zippel
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Quintel
mesh_terms: D000399:Air Pressure; D045853:Exhalation; D006801:Humans; D001239:Inhalation; D008328:Man-Machine Systems; D008397:Masks; D008954:Models, Biological; D063087:Noninvasive Ventilation / Q000379:methods*; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*; D056152:Respiratory Rate; D012122:Ventilators, Mechanical
keywords: COPD; NIV; chronic obstructive pulmonary disease; cycling; noninvasive ventilation; patient-ventilator interaction