title: A diaphragmatic electrical activity-based optimization strategy during pressure support ventilation improves synchronization but does not impact work of breathing.
abstract: BACKGROUND
  Poor patient-ventilator synchronization is often observed during pressure support ventilation (PSV) and has been associated with prolonged duration of mechanical ventilation and poor outcome. Diaphragmatic electrical activity (Eadi) recorded using specialized nasogastric tubes is a surrogate of respiratory brain stem output. This study aimed at testing whether adapting ventilator settings during PSV using a protocolized Eadi-based optimization strategy, or Eadi-triggered and -cycled assisted pressure ventilation (or PSVN) could (1) improve patient-ventilator interaction and (2) reduce or normalize patient respiratory effort as estimated by the work of breathing (WOB) and the pressure time product (PTP).
  
  
  METHODS
  This was a prospective cross-over study. Patients with a known chronic pulmonary obstructive or restrictive disease, asynchronies or suspected intrinsic positive end-expiratory pressure (PEEP) who were ventilated using PSV were enrolled in the study. Four different ventilator settings were sequentially applied for 15 minutes (step 1: baseline PSV as set by the clinician, step 2: Eadi-optimized PSV to adjust PS level, inspiratory trigger, and cycling settings, step 3: step 2 + PEEP adjustment, step 4: PSVN). The same settings as step 3 were applied again after step 4 to rule out a potential effect of time. Breathing pattern, trigger delay (Td), inspiratory time in excess (Tiex), pressure-time product (PTP), and work of breathing (WOB) were measured at the end of each step.
  
  
  RESULTS
  Eleven patients were enrolled in the study. Eadi-optimized PSV reduced Tdwithout altering Tiexin comparison with baseline PSV. PSVNreduced Tdand Tiexin comparison with baseline and Eadi-optimized PSV. Respiratory pattern did not change during the four steps. The improvement in patient-ventilator interaction did not lead to changes in WOB or PTP.
  
  
  CONCLUSIONS
  Eadi-optimized PSV allows improving patient ventilator interaction but does not alter patient effort in patients with mild asynchrony.
  
  
  BACKGROUND
  Clinicaltrials.gov identifier: NCT 02067403 . Registered 7 February 2014.
authors.affiliation: Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.|Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada.|Medical Intensive Care Unit, Hospital of Angers, University of Angers, Angers, France.
authors.forename: Francois
authors.initials: F
authors.lastname: Beloncle
authors.affiliation: Medical Intensive Care Unit, Hospital of Angers, University of Angers, Angers, France.|Adult Intensive Care and Burn Unit, University Hospital of Lausanne (CHUV), Lausanne, Switzerland.
authors.forename: Lise
authors.initials: L
authors.lastname: Piquilloud
authors.affiliation: Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.|Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada.|Division of Respiratory Diseases and Tuberculosis, Department of Medicine, Faculty of Medicine Siriraj Hospital, Bangkok, Thailand.
authors.forename: Nuttapol
authors.initials: N
authors.lastname: Rittayamai
authors.affiliation: Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada.
authors.forename: Christer
authors.initials: C
authors.lastname: Sinderby
authors.affiliation: CHU de Bordeaux, Service d'Anesthesie-Reanimation 2, Pessac, 33600, France.
authors.forename: Hadrien
authors.initials: H
authors.lastname: Rozé
authors.affiliation: Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada. brochardl@smh.ca.|Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada. brochardl@smh.ca.
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
mesh_terms: D000368:Aged; D018592:Cross-Over Studies; D003964:Diaphragm / Q000294:innervation*; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D059725:Interactive Ventilatory Support / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods* / Q000592:standards*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods; D014939:Work of Breathing / Q000502:physiology
keywords: Asynchrony; Chronic pulmonary obstructive; Mechanical ventilation; Neurally adjusted ventilatory assist; Pressure support ventilation; Restrictive disease