Does NIV-NAVA Improve Diaphragmatic Function in Preterm Infants
Condition: Respiratory Disease
MeSH terms: Respiratory Tract Diseases; Respiration Disorders
Study type: Observational

Summary: 
      Non-Invasive Positive Pressure Ventilation (NIPPV) provides un-synchronized positive pressure
      and considered to be superior to nCPAP in preventing extubation failure. Recently,
      Non-Invasive Ventilation Neurally-Adjusted Ventilatory Assist (NIV-NAVA) was introduced to
      NICU. NAVA is a ventilation mode that uses the electrical activity of the patient's diaphragm
      (Edi-signal) to guide both timing and magnitude of the support. However, it is unknown
      whether NIV-NAVA is superior to NIPPV in preventing extubation failure and preventing BPD.

      Hence, the investigators aim to compare the effect of NIPPV and NIV-NAVA on diaphragm
      function in premature infants with RDS or evolving BPD. Our hypothesis is that infants
      treated with NIV-NAVA will have improved diaphragmatic function and lung scoring.
    

Detailed description: 
      STUDY POPULATION Premature infants with respiratory distress syndrome who are admitted to
      Mount Sinai NICU and are supported with NIPPV or NIV-NAVA.

      Inclusion criteria

        1. Infants that were born at 22 0/7 to 29 6/7 weeks gestation and admitted to the NICU at
           Mount Sinai Health System.

        2. Infants that are on NIPPV or NIV-NAVA respiratory support for at least 24 hours at the
           time of enrolment.

      Exclusion criteria

        1. Infants with congenital anomalies.

        2. Infants with known genetic disorder.

        3. Infants with known lung malformation or diaphragm dysfunction.

        4. Infants of whom parents declined consent.

      Study Design and settings:

      This is a prospective cohort study that includes premature infants born at 22 0/7 to 29 6/7
      weeks GA in Mount Sinai Hospital and admitted to the NICU. Written consent will be obtained
      from parents or guardians prior to enrolment in the study. Enrolment of eligible infants will
      start after obtaining approval from Mount Sinai Research Ethics Board and parent's consent.
      Recruitment will be done over one year, and the investigators are expecting to recruit about
      30 infants in the NIPPV group and similar number in the NIV-NAVA group.

      Time of assessment; Eligible infants will be identified by a member of the infant's circle of
      care. Parents of infants who are eligible for the study will be approached for consent. Chest
      ultrasound (lung ultrasound and diaphragmatic function assessment) will be performed at > 7
      days postnatally, provided that the infant is supported by either NIPPV or NIV-NAVA for at
      least 24 hours. CUS will be done prior to feeding to avoid any concerns of a full stomach on
      diaphragmatic assessment.

      Study procedure: Functional assessment of the diaphragm combined with lung ultrasound
      examination will be done by one of the investigators.

      Lung ultrasound assessment technique; Lung ultrasounds will be performed in a standardized
      manner. A longitudinal scan of the anterior and lateral chest walls will be performed. Three
      chest areas for each side (upper anterior, lower anterior, and lateral) will be assessed.
      Each area will have a score of 0 to 3 points with a total score between 0 to 18, which
      inversely correlates with lung aeration.

      Diaphragmatic assessment technique; Diaphragm assessment will be performed in the supine
      position. To measure diaphragmatic excursion, the curvilinear probe will be placed on the
      lower intercostal spaces between the mid-clavicular and anterior axillary lines on the right
      side and between the anterior and mid-axillary lines for the left side. Using the B mode, the
      proper exploration line of the diaphragm will be detected by directing the beam perpendicular
      to the posterior third of the right hemidiaphragm. By M mode, the cyclic caudal diaphragmatic
      displacement with respiration will be measured as the perpendicular distance between the most
      caudal point of the liver or spleen at the end of expiration and the end of inspiration. The
      average of three respiratory cycles will be taken.

      The assessment of the diaphragmatic efficiency as a pressure generator will be evaluated
      using the diaphragmatic thickness fraction. Diaphragmatic thickness will be measured at the
      apposition zone which can be obtained by placing the linear transducer above the 10th rib in
      the mid-axillary or anterior axillary lines in the right intercostal spaces. By B mode, three
      distinct layers will be seen, the diaphragm as a hypo-echoic area bordered by two clear
      echogenic lines of the pleural membrane (upper line) and the peritoneal membrane (lower
      line). Using M-mode tracing, inspiratory diaphragmatic thickness will be measured as the
      maximum perpendicular distance between pleural and peritoneal layers and by the same way
      expiratory diaphragmatic thickness will be recorded. diaphragmatic thickness fraction will be
      calculated using the following formula:

      diaphragmatic thickness fraction = [(inspiratory thickness - expiratory thickness)/expiratory
      thickness] x 100.

      The average of the calculated diaphragmatic thickness fraction from three respiratory cycles
      will be estimated. The higher scores the better the diaphragmatic function. All Chest
      ultrasound assessments will be undertaken using a standard aseptic technique.
    

Intervention name(s): Chest ultrasound
Intervention type(s): Other
Intervention description(s): Chest ultrasound will be performed to eligiable (consented) patient after being on the respiratory support (NIV-NAVA vs NIPPV) for at least 24 hours. Both diaphragmatic function and lung ultrasound score will performed. Investigator interpreting the scans will be blind to patients type of respiratory support or clinical status.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Infants that were born between 22 0/7 to 29 6/7 weeks gestation and were admitted to the
        NICU at Mount Sinai Health System will be eligible for the study. Infants will be enrolled
        after obtaining parents' consent and Research Ethics Board approval
      
Keywords: preterm; neonates; Ultrasound; non-invasive; ventilation; Diaphragm; Lung; NIV-NAVA; NIPPV