title: Impact of ventilatory modes on the breathing variability in mechanically ventilated infants.
abstract: OBJECTIVE
  Reduction of breathing variability is associated with adverse outcome. During mechanical ventilation, the variability of ventilatory pressure is dependent on the ventilatory mode. During neurally adjusted ventilatory assist (NAVA), the support is proportional to electrical activity of the diaphragm (EAdi), which reflects the respiratory center output. The variability of EAdi is, therefore, translated into a similar variability in pressures. Contrastingly, conventional ventilatory modes deliver less variable pressures. The impact of the mode on the patient's own respiratory drive is less clear. This study aims to compare the impact of NAVA, pressure-controlled ventilation (PCV), and pressure support ventilation (PSV) on the respiratory drive patterns in infants. We hypothesized that on NAVA, EAdi variability resembles most of the endogenous respiratory drive pattern seen in a control group.
  
  
  METHODS
  Electrical activity of the diaphragm was continuously recorded in 10 infants ventilated successively on NAVA (5 h), PCV (30 min), and PSV (30 min). During the last 10 min of each period, the EAdi variability pattern was assessed using non-rhythmic to rhythmic (NRR) index. These variability profiles were compared to the pattern of a control group of 11 spontaneously breathing and non-intubated infants.
  
  
  RESULTS
  In control infants, NRR was higher as compared to mechanically ventilated infants (p < 0.001), and NRR pattern was relatively stable over time. While the temporal stability of NRR was similar in NAVA and controls, the NRR profile was less stable during PCV. PSV exhibited an intermediary pattern.
  
  
  CONCLUSIONS
  Mechanical ventilation impacts the breathing variability in infants. NAVA produces EAdi pattern resembling most that of control infants. NRR can be used to characterize respiratory variability in infants. Larger prospective studies are necessary to understand the differential impact of the ventilatory modes on the cardio-respiratory variability and to study their impact on clinical outcomes.
authors.affiliation: Department of Pediatrics, CHU Sainte-Justine, Université de Montréal , Montreal, QC , Canada.
authors.forename: Florent
authors.initials: F
authors.lastname: Baudin
authors.affiliation: Department of Mathematics, University of Toronto , Toronto, ON , Canada.
authors.forename: Hau-Tieng
authors.initials: HT
authors.lastname: Wu
authors.affiliation: Pediatric Critical Care Unit, Geneva University Hospital , Geneva , Switzerland.
authors.forename: Alice
authors.initials: A
authors.lastname: Bordessoule
authors.affiliation: Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, ON , Canada ; Department of Pediatrics, University of Toronto , Toronto, ON , Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Beck
authors.affiliation: Department of Pediatrics, CHU Sainte-Justine, Université de Montréal , Montreal, QC , Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Jouvet
authors.affiliation: Department of Obstetrics and Gynecology, CHU Ste-Justine Research Center, Université de Montréal , Montreal, QC , Canada ; Department of Neurosciences, CHU Ste-Justine Research Center, Université de Montréal , Montreal, QC , Canada ; Centre de recherche en reproduction animale, Université de Montréal , St-Hyacinthe, QC , Canada.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Frasch
authors.affiliation: Department of Pediatrics, CHU Sainte-Justine, Université de Montréal , Montreal, QC , Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Emeriaud
keywords: children; diaphragm; mechanical ventilation; neurally adjusted ventilatory support; pediatric intensive care