Measuring Thickness of the Normal Diaphragm in Children Via Ultrasound.
Condition: Mechanical Ventilation Complication; Pediatric ALL; Intensive Care Unit Acquired Weakness
Study type: Interventional

Summary: 
      Critically ill children treated with invasive mechanical ventilation (iMV) in a paediatric
      intensive care unit (PICU) may suffer from complications leading to prolonged duration of
      ventilation and PICU stay. Prolonged ventilation is associated with haemodynamic dysfunction,
      neuromuscular insufficiency, malnutrition, metabolic disorders and diaphragmatic muscle
      weakness. Evidence from adult critical care supports the existence of ventilator induced
      diaphragmatic dysfunction, defined as a iMV-induced loss of diaphragmatic force - generating
      capacity - characterised by muscle fibre atrophy, myofibril necrosis and disorganization.

      Diaphragm function or contractility can be assessed by measuring the diaphragm thickening
      during inspiration and expiration with ultrasound and is expressed as a thickening fraction
      (TF).

      A low diaphragm contractile activity in adults has been associated with rapid decreases in
      diaphragm thickness, whereas high contractile activity has been associated with increases in
      diaphragm thickness. Contractile activity decreased with increasing ventilator driving
      pressure and controlled ventilator mode. Maximal thickening fraction (a measure of diaphragm
      function) was lower in patients with decreased as well as increased diaphragm thickness than
      in patients with unchanged thickness (p=0.05). Titrating ventilatory support to maintain
      normal levels of inspiratory effort may prevent changes in diaphragm configuration associated
      with iMV, but more research is needed to confirm this supposition.

      Only one study has shown the presence of diaphragm atrophy in critically ill children on iMV
      for acute respiratory failure. The diaphragm contractility, measured as thickening fraction,
      was strongly correlated with a spontaneous breathing fraction.

      Norm data for diaphragmatic thickness and TF in children are only available for healthy
      neonates (n=15) and children (n=48) from 8 till 20 years of age.

      The purpose of this study is to determine values of normal diaphragm thickness and TF in
      children aged 0-8 years by ultrasound. This age range reflects the largest patient group
      treated in the PICU.

      Once these values are known, the clinical relevance of the measuring of the diaphragm
      thickness of ventilated children by ultrasound can be further studied.

      Objective of the study:

      Primary objective: To determine diaphragm thickness and thickening fraction in healthy
      children below or equal to 8 years of age.

      Secondary objective: To determine the interrater reliability of operators performing the
      ultra-sound

      Study design:

      prospective, cohort study.

      Study population:

      Healthy children in four age groups: 0-6 months; 6 months-1 year; 2-4 years; and 5-8 years.

      Participants will be recruited in two ways:

      Group 1. Parents of children scheduled to undergo a daycare procedure will asked permission
      for their child to join the study. These children undergo a minor procedure and are assumed
      to have a normal diaphragm; therefore are considered 'healthy''.

      Group 2. Health professionals working on the PICU or other departments of Erasmus MC-Sophia
      as well as family, friends and neighbours of members of the research group will be asked to
      recruit 'healthy' children. The investigators will recruit participants by means of brochures
      in which children and/or caregivers are invited to contact the researchers when interested to
      participate in this study.

      Primary study parameters/outcome of the study:

      To determine diaphragm thickness and thickening fraction in healthy children below or equal
      to 8 years of age.

      Secondary study parameters/outcome of the study (if applicable):

      To determine the interrater reliability of operators performing the ultra-sound
    


Intervention name(s): diaphragm thickness and thickening fraction
Intervention type(s): Diagnostic Test
Intervention description(s): Ultrasound measurement of the diaphragm will be performed with the use of a Sono Site SII, portable system in B mode with the child in a 30-degree supine position. The diaphragm thickness will be measured with a high frequency (4-10 MHz) linear array transducer placed in the ninth or tenth intercostal space between the anterior and midaxillary lines in the zone of apposition between lung and liver.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Screening