Electrical impedance tomography (EIT) enables assessment of regional lung ventilation at the bedside. EIT has been safely used in newborn infants to image intrathoracic lung volume patterns as early as from the first minute of life. This prospective single-centre observational study is to identify optimal PEEP in infants on respiratory support by measurements of EIT, FOT and SOPI.
22+0 to 41+6 weeks' gestational age
Requiring mechanical ventilation
Written informed parental consent
Major congenital malformations including lung and cardiac malformations
Infants on high frequency oscillatory ventilation
Lack of written informed parental consent
All newborn infants admitted to the University Children's Hospital Basel UKBB requiring mechanical ventilation are eligible for the study.
Cohort
Prospective
Electrical impedance tomography (EIT)
Diagnostic testEIT is the measurement of impedance changes of the lung against the flow of alternating electrical currents applied to the thorax. The signal of the electrodes is transmitted to a monitor, which enables real-time assessment of lung aeration and changes in lung volume. EIT is able to reconstruct impedance changes with a high temporal resolution and allows calculation of tidal volumes, relative stretch of lung tissue and areas of poor ventilation. Areas with impedance changes of \< 10 % of the maximum impedance changes are called 'Silent Spaces'.
Forced oscillation technique (FOT)
Diagnostic testFOT enables non-invasive assessment of lung mechanics using sound waves to inform about the respiratory impedance of the respiratory system (Zrs). Reactance of the respiratory system (Xrs) as part of Zrs is a surrogate measure of compliance of the respiratory system. Xrs was previously used to identify optimal PEEP level, i.e., the PEEP at highest compliance equivalent, in newborn infants using a setup requiring research-specific hardware and software. The FOT module integrated in the commercially available neonatal ventilator is routinely used. FOT measurements are performed twice at each PEEP level to assess the reproducibility of the measurements.
Saturation oxygenation pressure index (SOPI)
Diagnostic testSOPI is assessed non-invasively and calculated from standard monitoring parameters such as PEEP, fraction of inspired oxygen pressure (FiO2) and peripheral oxyhaemoglobin saturation (SpO2) (PEEP x FiO2 x 100) / SpO2). SOPI is used to provide information on ventilation to perfusion ratio dependent on PEEP level.
Change in composite score consisting of proportionally weighted raw values of Silent Spaces, Xrs and SOPI (mechanical ventilation)
A composite score consisting of proportionally weighted raw values of Silent Spaces, respiratory reactance (Xrs) and SOPI (mechanical ventilation)
Change in composite score consisting of proportionally weighted raw values of Silent Spaces and SOPI (non-invasive respiratory support)
A composite score consisting of proportionally weighted raw values of Silent Spaces and SOPI (non-invasive respiratory support)
Change in Silent Spaces (areas of atelectasis as well as overdistension)
Silent Spaces measured by EIT (calculated from electrical impedance)
Change in respiratory reactance (Xrs) (measure of compliance of the respiratory system)
Respiratory reactance reflects inertance and compliance of the lungs and can be viewed as rebound resistance
Change in Delta impedance (ΔZ)
Delta impedance (ΔZ) is an additional EIT parameter
Change in centre of ventilation (CoV)
Centre of ventilation (CoV) is an additional EIT parameter
Change in tidal volume (VT,EIT)
Tidal volume (VT,EIT) is an additional EIT parameter
Change in driving pressure of the respiratory system (Peak plateau pressure - PEEP)
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