Electrical Impedance Tomography for Optimization of Positive End-Expiratory Pressure: Acute Respiratory Distress Syndrome

Study Overview
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Brief Summary
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Doctors follow a standard ventilator management strategy when making adjustments to the breathing machine to optimize the amount of oxygen into the lungs. The purpose of this study is to assess whether the EIT (electrical impedance tomography) device can be an additional useful tool for ventilator management and identifying the ideal positive end-expiratory pressure (PEEP).

Official Title
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Use of Electrical Impedance Tomography for Optimization of Positive End-Expiratory Pressure in Acute Respiratory Distress Syndrome

Conditions
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Acute Respiratory Distress Syndrome, ARDS

Intervention / Treatment
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* Other: Usual care
* Device: PEEP titration by EIT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Endotracheal ventilation for < 1 week (168 hours) Presence of all of the following conditions for < 48 hours i. Partial pressure of oxygen to percentage of inspired oxygen (PaO2/FiO2) < 150 with PEEP > 5 cm water for > 30 min. ii. bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules iii. respiratory failure not fully explained by cardiac failure or fluid overload -All criteria listed in (3) developed within 1 week of a known clinical insult or new or worsening respiratory symptoms Exclusion Criteria: Lack of informed consent Known pregnancy Extracorporeal membrane oxygenation (ECMO) use Severe chronic respiratory disease requiring home oxygen therapy or ventilation Calculated BMI of greater than 50

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Usual care then PEEP titration by Electrical Impedance Tomography (EIT)<br>Patients in the usual care first group will continue to receive mechanical ventilation according to the University of Michigan Acute Respiratory Distress Syndrome (ARDS) protocol high-PEEP arm | Other: Usual care<br>* Intervention is the standard basic lung protective ventilation strategy used at the University Hospital Respiratory Care at Michigan Medicine.<br>Device: PEEP titration by EIT<br>* PEEP Titration procedure involves two phases: a recruitment phase followed by a gradual reduction in the end-expiratory pressure phase (Decremental PEEP).<br>* Other names: Drager PulmoVista 500 EIT System;|
| Experimental: PEEP titration by EIT then usual care<br>Patients in the high PEEP titration by EIT first will have receive ventilation with a PEEP determined by EIT titration procedure. | Other: Usual care<br>* Intervention is the standard basic lung protective ventilation strategy used at the University Hospital Respiratory Care at Michigan Medicine.<br>Device: PEEP titration by EIT<br>* PEEP Titration procedure involves two phases: a recruitment phase followed by a gradual reduction in the end-expiratory pressure phase (Decremental PEEP).<br>* Other names: Drager PulmoVista 500 EIT System;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mechanical Power | Mechanical power (MP) is the energy imparted to the lung from the mechanical ventilator. It is calculated as listed below, where respiratory rate = RR, tidal volume = TV, Ppeak = peak airway pressure, Pplat = plateau airway pressure and PEEP = positive end-expiratory pressure. Mechanical power determined for the difference between Treatment 1 and Treatment 2. Values shown represent data gathered at the end of the designated assignment listed below, regardless of whether that assignment was Treatment 1 or Treatment 2. MP = 0.098 X RR X TV (Ppeak-[Pplat-PEEP/2]) | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at end of treatment. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Lung Inflammation as Measured by Physiologic Parameter: Partial Pressure of Arterial Oxygen/Fraction of Inspired Oxygen (P/F Ratio) | P/F ratio is a measurement of oxygenation and, where arterial oxygen in mmHg is PaO2 and percentage of inspired oxygen is FiO2. It calculated as: PaO2/FiO2. P/F ratio determined for the difference between Intervention 1 and Intervention 2 | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at baseline and end of treatment. | 
| Change in Lung Inflammation as Measured by Physiologic Parameter: Plateau Pressure | Plateau pressure is a measurement of lung compliance and is the airway pressure obtained during a brief inspiratory hold after delivering a tidal volume breath during invasive mechanical ventilation. Plateau pressure determined for the difference between Intervention 1 and Intervention 2 | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at baseline and end of treatment. | 
| Lung Inflammation as Measured by Physiologic Parameter: Driving Pressure | Driving pressure is the force of airway push into the lung while receiving invasive mechanical ventilation and is calculated as Plateau pressure - Positive end-expiratory pressure. Driving pressure determined for the difference between Intervention 1 and Intervention 2 | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at end of treatment. | 
| Change in Lung Inflammation as Measured by Physiologic Parameter: Static Compliance | Static lung compliance is a measurement of lung stiffness due to disease, with a lower compliance representing stiffer lungs. It is calculated as: Tidal volume / (Plateau pressure - PEEP). Static compliance determined for the difference between Intervention 1 and Intervention 2 | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at baseline and end of treatment. | 
| Partial Pressure of Arterial Oxygen (PaO2) | PaO2 is the partial pressure of arterial oxygen measured in mmHg. PaO2 determined for the difference between Intervention 1 and Intervention 2. | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at end of treatment. | 
| Dynamic Compliance (Cdyn) | Dynamic compliance is a measurement of the resistance of the lungs and airways to gas installation from the mechanical ventilator and is measured as Peak airway pressure / Plateau airway pressure - PEEP). Dynamic compliance determined for the difference between Intervention 1 and Intervention 2. | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at end of treatment. | 
| Change in Compliance Over the Last 20% of Inspiration (C20/Dyn) | C20 is the compliance that results when only the upper 20% of the applied pressure range is taken into account. The C20/Dyn ratio appears to effectively quantitate evidence of lung over distention during mechanical ventilation. This is a unit-less measure as both numerator and denominator are measured in cm water. C20/dyn determined for the difference between Intervention 1 and Intervention 2. | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at baseline and end of treatment. | 
| Ultrasound Surrogates of Lung Aeration | Lung ultrasound inflation scores are calculated by summing regional scores (0-3 points), with higher scores indicating worse condition of the lung. Scores were obtained in six regions of each lung (i.e., up and down anterior, medial, and posterior chest wall). This is a unit-less measure. Ultrasound lung surrogates of lung inflation determined for the difference between Intervention 1 and Intervention 2. | Participants received Treatment 1 (either Usual Care or PEEP EIT) for approximately 6 hours after randomization and then received Treatment 2 for an additional 14-18 hours following crossover. Measurement was done at end of treatment. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Electrical Impedance Tomography, Ventilator, Lung, Respiration