title: Neurally adjusted ventilatory assist in critically ill postoperative patients: a crossover randomized study.
abstract: BACKGROUND
  Neurally adjusted ventilatory assist (NAVA) is a new mode of mechanical ventilation that delivers ventilatory assist in proportion to the electrical activity of the diaphragm. This study aimed to compare the ventilatory and gas exchange effects between NAVA and pressure support ventilation (PSV) during the weaning phase of critically ill patients who required mechanical ventilation subsequent to surgery.
  
  
  METHODS
  Fifteen patients, the majority of whom underwent abdominal surgery, were enrolled. They were ventilated with PSV and NAVA for 24 h each in a randomized crossover order. The ventilatory parameters and gas exchange effects produced by the two ventilation modes were compared. The variability of the ventilatory parameters was also evaluated by the coefficient of variation (SD to mean ratio).
  
  
  RESULTS
  Two patients failed to shift to NAVA because of postoperative bilateral diaphragmatic paralysis, and one patient interrupted the study because of worsening of his sickness. In the other 12 cases, the 48 h of the study protocol were completed, using both ventilation modes, with no signs of intolerance or complications. The Pao2/Fio2 (mean ± SD) ratio in NAVA was significantly higher than with PSV (264 ± 71 vs. 230 ± 75 mmHg, P < 0.05). Paco2 did not differ significantly between the two modes. The tidal volume (median [interquartile range]) with NAVA was significantly lower than with PSV (7.0 [6.4-8.6] vs. 6.5 [6.3-7.4] ml/kg predicted body weight, P < 0.05).Variability of insufflation airway pressure, tidal volume, and minute ventilation were significantly higher with NAVA than with PSV. Electrical activity of the diaphragm variability was significantly lower with NAVA than with PSV.
  
  
  CONCLUSIONS
  Compared with PSV, respiratory parameter variability was greater with NAVA, probably leading in part to the significant improvement in patient oxygenation.
authors.affiliation: Intensive Care Unit, Anesthesiology and Critical Care Department B, Saint Eloi Teaching Hospital, Montpellier, France.
authors.forename: Yannael
authors.initials: Y
authors.lastname: Coisel
authors.forename: Gerald
authors.initials: G
authors.lastname: Chanques
authors.forename: Boris
authors.initials: B
authors.lastname: Jung
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Constantin
authors.forename: Xavier
authors.initials: X
authors.lastname: Capdevila
authors.forename: Stefan
authors.initials: S
authors.lastname: Matecki
authors.forename: Salvatore
authors.initials: S
authors.lastname: Grasso
authors.forename: Samir
authors.initials: S
authors.lastname: Jaber
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003422:Critical Care / Q000379:methods*; D016638:Critical Illness; D018592:Cross-Over Studies; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010101:Oxygen Consumption / Q000502:physiology; D011183:Postoperative Complications / Q000503:physiopathology; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology; D015300:Ventilator Weaning