Impact of NAVA (Neurally Adjusted Ventilatory Assist) on Ventilatory Demand During Pediatric Non-Invasive Ventilation
Condition: Respiratory Failure
MeSH terms: Respiratory Insufficiency
Study type: Interventional

Summary: 
      Mechanical ventilation permits to support the work of breathing in case of respiratory
      failure, but therapy also has many side effects. Non-invasive ventilation (NIV), which
      delivers the ventilatory assist via a face mask or nasal canula, permits to decrease these
      complications. However, NIV is not always successful and half of children in respiratory
      failure finally require invasive ventilation. A major cause of NIV failure is the ventilator
      inability to detect patient efforts. The new ventilatory mode NAVA (neurally adjusted
      ventilatory assist) improves the detection of patient efforts during mechanical ventilation.
      The hypothesis of this study is that NAVA improves synchrony during pediatric NIV and
      therefore permits to unload the patient ventilatory efforts.
    

Detailed description: 
      Nasogastric tube installation to monitor electrical activation of the diaphragm (EAdi):

      A specific nasogastric tube equipped with an array of microelectrodes (Edi catheter, Maquet,
      Solna, Sweden) will be installed after inclusion. This tube has an external aspect and size
      (6F, 8F, or 12F depending on the patient size) similar to usual nasogastric tubes. The
      gastric tube installation is extremely frequent in pediatric ICU, and systematic in patients
      with ventilatory support, to empty the gastric gas and permit the feeding. The new tube will
      stay in place after the study and could be used as a classic tube. The catheter position in
      esophagus will be adjusted using a special window of the Servo i ventilator screen, which
      permits to confirm the correct positioning close to the diaphragm [Barwing 2009]. It has
      recently been confirmed that Edi catheter placement is not difficult and that the correct
      placement of the nasogastric tube is actually facilitated by the possibility of activity
      monitoring [Green 2011].

      RIP jacket installation:

      A special jacket adapted to the patient size will be installed to monitor the lung volume
      changes by impedance plethysmography (RIP). This sleeveless jacket is constituted of a large
      band of distensible cloth in which 2 metallic coils are coated to record the impedance
      changes created by the ventilation. The RIP coils will be connected to the RIP monitoring
      module, and no volume calibration will be done to avoid the manipulation of patient airway.
      RIP monitoring is completely non-invasive and no complications are expected [Emeriaud
      2010][Emeriaud 2008].

      Baseline measurements:

      The Edi tube is connected to the Servo i to monitor EAdi, but the patient remains connected
      to its usual ventilator with unmodified ventilator settings. Airway pressure, respiratory
      volume and flow will be recorded simultaneously with EAdi during 30 minutes.

      Ventilator change:

      If a different ventilator was used prior to the study, the patient will be installed on a
      Servo i ventilator, initially with the same ventilatory settings.

      Determination of NAVA parameters:

      The positive end expiratory pressure (PEEP) will not be modified. The NAVA level - the
      proportionality factor that converts EAdi (microV) into pressure support (cmH2O) - will be
      set using a specific window which simulates the pressure that would be delivered in NAVA. The
      NAVA level will be initially adjusted to match the simulated pressure with the actual assist
      pressure. If the patient is on CPAP (i.e. no assist pressure), the NAVA level will be
      initially set to match an assist pressure of 5 cmH2O above PEEP. The maximal pressure alarm
      will be set at 30 cmH2O.

      NAVA period:

      The NAVA mode will be activated for one hour, under the continuous supervision by a physician
      involved in the study, and with a continuous monitoring of vital signs including cardiac and
      respiratory rate, SaO2, respiratory distress signs, patient agitation, and the normal
      function of the ventilator. The NAVA level will be adjusted if the patient breathing
      frequency is > 40/min (progressive increase of NAVA level) or < 12/min (decrease of NAVA
      level), or if the delivered pressure is low (<3 cmH2O) due to air leaks. Ventilatory
      pressure, flow and volumes and EAdi will be continuously recorded during the last 30 minutes.

      Second period with conventional NIV settings:

      The patient will be installed again with the ventilatory settings prescribed prior to the
      study, and the ventilatory data will be recorded again for 30 minutes.

      During the entire study, "usual" modifications of settings (e.g. adaptation of assist level,
      FiO2, or PEEP) considered by the attending physician, the nurse, or a respiratory therapist,
      will be permitted and documented.

      End of the study:

      At the end of the study, if a clear clinical benefit of one mode or setting is observed
      during the study, the attending physician will be informed to permit the optimal adaptation
      of the ventilatory assist.
    

Intervention name(s): Neurovent Monitor XIII; Neurovent Monitor XIII; Neurovent Monitor XIII; Neurovent Monitor XIII; Neurovent Monitor XIII
Intervention type(s): Device; Device; Device; Device; Device
Intervention description(s): Nasogastric tiube installation to monitor EAdi; RIP jacket installation; Ventilator change (if a different ventilator was used prior to the study).; Determination of NAVA parametersVentilator; Second period with conventional NIV settings
Other intervention name(s): Health Canada approval number: 186536
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Supportive Care
Keywords: Nava; Non Invasive Ventilation