title: Non-invasive neurally adjusted ventilatory assist in rabbits with acute lung injury.
abstract: OBJECTIVE
  Neurally adjusted ventilatory assist uses the electrical activity of the diaphragm (EAdi)--a pneumatically-independent signal--to control the timing and pressure of the ventilation delivered, and should not be affected by leaks. The aim of this study was to evaluate whether NAVA can deliver assist in synchrony and proportionally to EAdi after extubation, with a leaky non-invasive interface.
  
  
  METHODS
  Prospective, controlled experimental study in an animal laboratory.
  
  
  METHODS
  Ten rabbits, anesthetized, mechanically ventilated.
  
  
  METHODS
  Following lung injury, the following was performed in sequential order: (1) NAVA delivered via oral endotracheal tube with PEEP; (2) same as (1) without PEEP; (3) non-invasive NAVA at unchanged NAVA level and no PEEP via a single nasal prong; (4) no assist; (5) non-invasive NAVA at progressively increasing NAVA levels.
  
  
  RESULTS
  EAdi, esophageal pressure, blood gases and hemodynamics were measured during each condition. For the same NAVA level, the mean delivered pressure above PEEP increased from 3.9 +/ 1.4 cmH2O (intubated) to 7.5 +/- 3.8 cmH2O (non-invasive) (p<0.05) because of increased EAdi. No changes were observed in PaO2 and PaCO2. Increasing the NAVA level fourfold during non-invasive NAVA restored EAdi and esophageal pressure swings to pre-extubation levels. Triggering (106 +/- 20 ms) and cycling-off delays (40 +/- 21 ms) during intubation were minimal and not worsened by the leak (95 +/- 13 ms and 33 +/- 9 ms, respectively).
  
  
  CONCLUSIONS
  NAVA can be effective in delivering non-invasive ventilation even when the interface with the patient is excessively leaky, and can unload the respiratory muscles while maintaining synchrony with the subject's demand.
authors.affiliation: Sunnybrook Health Sciences Centre, Department of Newborn & Developmental Paediatrics, 76 Grenville, 4th floor (Paediatrics), M5S 1B6, Toronto, Ontario, Canada. jennifer.beck@sunnybrook.ca
authors.forename: Jennifer
authors.initials: J
authors.lastname: Beck
authors.forename: Lukas
authors.initials: L
authors.lastname: Brander
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Slutsky
authors.forename: Maureen C
authors.initials: MC
authors.lastname: Reilly
authors.forename: Michael S
authors.initials: MS
authors.lastname: Dunn
authors.forename: Christer
authors.initials: C
authors.lastname: Sinderby
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002302:Cardiac Output; D003964:Diaphragm / Q000294:innervation / Q000503:physiopathology; D004594:Electrophysiology; D006851:Hydrochloric Acid; D008297:Male; D011175:Positive-Pressure Respiration; D011817:Rabbits; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D013990:Tidal Volume; D014628:Vagotomy
chemical_list: D006851:Hydrochloric Acid