title: Daily titration of neurally adjusted ventilatory assist using the diaphragm electrical activity.
abstract: OBJECTIVE
  To determine the feasibility of daily titration of the neurally adjusted ventilatory assist (NAVA) level in relation to the maximal diaphragmatic electrical activity (EAdi(maxSBT)) measured during a spontaneous breathing trial (SBT) during pressure support ventilation (PSV).
  
  
  METHODS
  The study included 15 consecutive patients in whom mechanical ventilation weaning was initiated with the NAVA mode. EAdi(maxSBT) was determined daily during an SBT using PSV with 7 cmH2O of inspiratory pressure and no positive end-expiratory pressure (PEEP). If the SBT was unsuccessful, NAVA was used and the level was then adjusted to obtain an EAdi of ~60% of the EAdi(maxSBT). Arterial blood gas analyses were performed 20 min after each change in NAVA level.
  
  
  RESULTS
  Three patients were dropped from the study at day 4 because of worsening of their sickness. The median duration of NAVA ventilation was 4.5 days (IQR 3-6.5). From day 1 to extubation, EAdi(maxSBT) and EAdi increased significantly from 16.6 (9.6) to 21.7 (10.3) μV (P = 0.013) and from 10.0 (5.5) to 15.1 (9.2) μV (P = 0.026), respectively. The pressure delivered significantly decreased from 20 (8) to 10 (5) cmH2O (P = 0.003). Conversely, tidal volume, carbon dioxide tension, and pH values remained unchanged during the same period.
  
  
  CONCLUSIONS
  These results suggest that daily titration of NAVA level with an electrical goal of ~60% EAdi(maxSBT) is feasible and well tolerated. The respiratory mechanics improvement and increase in respiratory drive allowed for a daily reduction of the NAVA level while preserving breathing, oxygenation, and alveolar ventilation until extubation.
authors.affiliation: Department of Anesthesia and Intensive Care II, Thoracic Intensive Care Unit, Centre Hospitalier Universitaire Bordeaux, Groupe Sud, Pessac, Université Victor Segalen Bordeaux II, Bordeaux, France. hadrien.roze@chu-bordeaux.fr
authors.forename: Hadrien
authors.initials: H
authors.lastname: Rozé
authors.forename: Abdelghani
authors.initials: A
authors.lastname: Lafrikh
authors.forename: Virginie
authors.initials: V
authors.lastname: Perrier
authors.forename: Arnaud
authors.initials: A
authors.lastname: Germain
authors.forename: Antoine
authors.initials: A
authors.lastname: Dewitte
authors.forename: Francis
authors.initials: F
authors.lastname: Gomez
authors.forename: Gérard
authors.initials: G
authors.lastname: Janvier
authors.forename: Alexandre
authors.initials: A
authors.lastname: Ouattara
mesh_terms: D000403:Airway Resistance / Q000502:physiology; D003422:Critical Care / Q000379:methods*; D003964:Diaphragm / Q000503:physiopathology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000503:physiopathology; D056152:Respiratory Rate / Q000502:physiology; D016896:Treatment Outcome; D015300:Ventilator Weaning / Q000379:methods*