title: Respiratory pattern during neurally adjusted ventilatory assist in acute respiratory failure patients.
abstract: OBJECTIVE
  To investigate the effect of a wide range of assistance levels during neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) on respiratory pattern, breathing variability, and incidence of tidal volumes (V                            (T)) above 8 and 10 ml/kg in acute respiratory failure patients.
  
  
  METHODS
  Eight increasing NAVA levels (0.5, 1, 1.5, 2, 2.5, 3, 4, and 5 cmH(2)O/μV) and four increasing pressure support (PSV) levels (4, 8, 12, and 16 cmH(2)O) were applied to obtain 10 min of stable recordings in 15 patients.
  
  
  RESULTS
  One out of 15 patients did not sustain the NAVA levels of 3, 4, and 5 cmH(2)O/μV and was excluded. The 5 cmH(2)O/μV NAVA level was not tolerated by three patients and it was excluded. Increasing NAVA levels were associated with decreased diaphragm electrical activity (EAdi), and, at variance with PSV, with small changes in V                            (T), no changes in respiratory rate (RR), and increases in V                            (T) and EAdi variability. At high NAVA levels, an increase in V                            (T) variability was associated with increased incidence of V                            (T) above 8 and 10 ml/kg and an uncomfortable respiratory pattern in some patients.
  
  
  CONCLUSIONS
  Increasing NAVA levels were associated with no effect on RR, small increase in V                            (T), and increase in V                            (T) and EAdi variability. Effective decrease in EAdi occurred at NAVA levels below 2-2.5 cmH(2)O/μV, while preserving respiratory variability and low risks of V                            (T) above 8 or 10 ml/kg.
authors: Department of Experimental Medicine, University of Milan-Bicocca, via Cadore 48, 20048 Monza, Milan, Italy. nicolo.patroniti@unimib.it
authors: Nicolò
authors: N
authors: Patroniti
authors: Giacomo
authors: G
authors: Bellani
authors: Erica
authors: E
authors: Saccavino
authors: Alberto
authors: A
authors: Zanella
authors: Giacomo
authors: G
authors: Grasselli
authors: Stefano
authors: S
authors: Isgrò
authors: Manuela
authors: M
authors: Milan
authors: Giuseppe
authors: G
authors: Foti
authors: Antonio
authors: A
authors: Pesenti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D059725:Interactive Ventilatory Support / Q000379:methods; D008297:Male; D008875:Middle Aged; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy*; D056152:Respiratory Rate