Electrical Impedance Tomography for Identification of Optimal Positive End-expiratory Pressure in Newborn Infants

Study Overview
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Brief Summary
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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.

Detailed Description
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Evidence-based guidelines on the optimal level of positive end-expiratory pressure (PEEP) in newborn infants on respiratory support do not exist. Furthermore, there is a lack of simple bed-side parameters to guide clinicians towards the optimal PEEP level. Nevertheless, PEEP requires individual adjustment to minimize ventilator induced lung injury (VILI), shorten the duration of mechanical ventilation and reduce respiratory long-term morbidity. Potential techniques to assess optimal PEEP level in infants on respiratory support include electrical impedance tomography (EIT), the forced oscillation technique (FOT) and the saturation oxygenation pressure index (SOPI). EIT is a promising non-invasive technique that provides information on regional changes in lung aeration and ventilation inhomogeneity. FOT is used in mechanically ventilated or spontaneously breathing infants and provides information on reactance (Xrs) and resistance (Rrs) of the respiratory system. SOPI is a score calculated from the PEEP level, the amount of administered oxygen (FiO2) and the infant's peripheral oxyhaemoglobin saturation (SpO2). SOPI provides information on the ventilation to perfusion ratio dependent on the PEEP level. EIT, FOT and SOPI seem promising tools for identification of optimal PEEP in newborn infants on respiratory support. In particular, a combination of information on regional ventilation (by EIT), global lung mechanics (by FOT) and ventilation to perfusion ratio (by SOPI) will improve the understanding of optimal PEEP and may reduce long-term respiratory sequelae. This prospective single-centre observational study is to identify optimal PEEP in infants on respiratory support by measurements of EIT, FOT and SOPI. Measurements are performed once daily during the first three days on respiratory support and are repeated in weekly intervals if the infant remains mechanically ventilated. An additional measurement is planned after extubation.

Official Title
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Electrical Impedance Tomography for Identification of Optimal Positive End-expiratory Pressure in Newborn Infants

Conditions
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Positive End-expiratory Pressure (PEEP)

Intervention / Treatment
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* Diagnostic Test: Electrical impedance tomography (EIT)
* Diagnostic Test: Forced oscillation technique (FOT)
* Diagnostic Test: Saturation oxygenation pressure index (SOPI)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 22+0 to 41+6 weeks' gestational age Requiring mechanical ventilation Written informed parental consent Exclusion Criteria: Major congenital malformations including lung and cardiac malformations Infants on high frequency oscillatory ventilation Lack of written informed parental consent

Ages Eligible for Study
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Minimum Age: 0 Days
Maximum Age: 28 Days

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Infants on mechanical ventilation<br> | Diagnostic Test: Electrical impedance tomography (EIT)<br>* EIT 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'.<br>Diagnostic Test: Forced oscillation technique (FOT)<br>* FOT 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.<br>Diagnostic Test: Saturation oxygenation pressure index (SOPI)<br>* SOPI 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.<br>|
| Infants on non-invasive respiratory support<br> | Diagnostic Test: Electrical impedance tomography (EIT)<br>* EIT 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'.<br>Diagnostic Test: Saturation oxygenation pressure index (SOPI)<br>* SOPI 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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) | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| 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) | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in Silent Spaces (areas of atelectasis as well as overdistension) | Silent Spaces measured by EIT (calculated from electrical impedance) | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| 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 | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in Saturation oxygenation pressure index (SOPI) | 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) | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Delta impedance (ΔZ) | Delta impedance (ΔZ) is an additional EIT parameter | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in centre of ventilation (CoV) | Centre of ventilation (CoV) is an additional EIT parameter | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in tidal volume (VT,EIT) | Tidal volume (VT,EIT) is an additional EIT parameter | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in driving pressure of the respiratory system (Peak plateau pressure - PEEP) |  | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in resistance (Rrs) of the respiratory system | Resistance (Rrs) is an additional FOT parameter | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in peak inspiratory pressure | Peak inspiratory pressure is a mechanical ventilation parameters | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in tidal volume per kg body weight (VT/kg) | Tidal volume per kg body weight (VT/kg) is a mechanical ventilation parameters | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in dynamic compliance | Dynamic compliance is a mechanical ventilation parameters | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in respiratory rate | Respiratory rate is a mechanical ventilation parameters | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 
| Change in transcutaneous CO2 pressure (tcpCO2) |  | Once daily during the first three days on respiratory support and weekly intervals if the infant remains mechanically ventilated (approx. 1 month) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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respiratory support, newborn infants, ventilator induced lung injury (VILI), mechanical ventilation, electrical impedance tomography (EIT), forced oscillation technique (FOT), saturation oxygenation pressure index (SOPI), ventilation to perfusion ratio, regional lung ventilation patterns, Silent Spaces