title: Patient-ventilator synchrony in Neurally Adjusted Ventilatory Assist (NAVA) and Pressure Support Ventilation (PSV): a prospective observational study.
abstract: BACKGROUND
  Weaning from mechanical ventilation is associated with the presence of asynchronies between the patient and the ventilator. The main objective of the present study was to demonstrate a decrease in the total number of patient-ventilator asynchronies in invasively ventilated patients for whom difficulty in weaning is expected by comparing neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) ventilatory modes.
  
  
  METHODS
  We performed a prospective, non-randomized, non-interventional, single-center study. Thirty patients were included in the study. Each patient included in the study benefited in an unpredictable way from both modes of ventilation, NAVA or PSV. Patients were successively ventilated for 23 h in NAVA or in PSV, and then they were ventilated for another 23 h in the other mode. Demographic, biological and ventilatory data were collected during this period. The two modes of ventilatory support were compared using the non-parametric Wilcoxon test after checking for normal distribution by the Kolmogorov-Smirnov test. The groups were compared using the chi-square test.
  
  
  RESULTS
  The median level of support was 12.5 cmH2O (4-20 cmH2O) in PSV and 0.8 cmH2O/μvolts (0.2-3 cmH2O/μvolts) in NAVA. The total number of asynchronies per minute in NAVA was lower than that in PSV (0.46 vs 1, p < 0.001). The asynchrony index was also reduced in NAVA compared with PSV (1.73 vs 3.36, p < 0.001). In NAVA, the percentage of ineffective efforts (0.77 vs 0.94, p = 0.036) and the percentage of auto-triggering were lower compared with PSV (0.19 vs 0.71, p = 0.038). However, there was a higher percentage of double triggering in NAVA compared with PSV (0.76 vs 0.71, p = 0.046).
  
  
  CONCLUSIONS
  The total number of asynchronies in NAVA is lower than that in PSV. This finding reflects improved patient-ventilator interaction in NAVA compared with the PSV mode, which is consistent with previous studies. Our study is the first to analyze patient-ventilator asynchronies in NAVA and PSV on such an important duration. The decrease in the number of asynchronies in NAVA is due to reduced ineffective efforts and auto-triggering.
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. hodane.y@chu-toulouse.fr.
authors.forename: Hodane
authors.initials: H
authors.lastname: Yonis
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. crognier.l@chu-toulouse.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Crognier
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. conil.jm@chu-toulouse.fr.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Conil
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. serres.i@chu-toulouse.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Serres
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. rouget.a@chu-toulouse.fr.
authors.forename: Antoine
authors.initials: A
authors.lastname: Rouget
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. virtos.m@chu-toulouse.fr.
authors.forename: Marie
authors.initials: M
authors.lastname: Virtos
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. cougot.p@chu-toulouse.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Cougot
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. minville.v@chu-toulouse.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Minville
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. fourcade.o@chu-toulouse.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Fourcade
authors.affiliation: Service de Réanimation Polyvalente, CHU Rangueil, 1 Avenue Jean Poulhès, Pôle d'Anesthésie et Réanimation, TSA 50032, 31059, Toulouse, Cedex 9, France. georges.b@chu-toulouse.fr.
authors.forename: Bernard
authors.initials: B
authors.lastname: Georges
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D059725:Interactive Ventilatory Support / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D018709:Statistics, Nonparametric; D015300:Ventilator Weaning