Electrical Impedance Tomography Measurements During Apnea Test in Patients With Suspected Brain Death

Study Overview
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Brief Summary
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Apnea testing is the final decisive examination in the strictly regulated process of brain death assessment. There is no standardized method found in the literature for apnea testing except for the inspection of possible spontaneous chest movements. In addition, the test itself lasts for several minutes leading to the collapse of the lungs. Electrical impedance tomography (EIT) is a non-invasive, real-time monitoring technique, which is suitable for detecting changes in lung volumes during ventilation. With its help, one can examine the spontaneous initiation of inspiration, the development of atelectasis and the reopening of collapsed regions by mechanical ventilation. Furthermore, the apnea test provides for analysing the effect of changes in pulmonary perfusion on impedance in the absence of noise generated by ventilation.

Detailed Description
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The aim of the study is to assess the eligibility of electrical impedance monitoring for the detection of possible spontaneous initiations of inspiration during apnea test in patients with suspected brain death. The study could contribute to the opening of new areas in the clinical use of the electrical impedance device. An additional aim is to observe the collapse and the reopening by recruitment manoeuvers of different pulmonary regions.

Official Title
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Electrical Impedance Tomography Measurements During Apnea Test in Patients With Suspected Brain Death

Conditions
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Brain Death

Intervention / Treatment
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* Diagnostic Test: Apnea test, alveolar recruitment


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with suspected brain death undergoing apnea test for detecting the absence of spontaneous breathing Exclusion Criteria: age under 18 pregnancy pulmonectomy, lung resection in the past medical history clinically end stage chronic obstructive pulmonary disease (COPD) severe hemodynamic instability (vasopressor refractory shock) severe bullous emphysema and/or spontaneous pneumothorax in the past medical history chest drainage in situ due to pneumothorax and/or bronchopleural fistula

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 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: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: apnea test, recruitment manoeuvre<br>Continuous electric impedance tomography (EIT) recording. Recording of initial vital parameters and arterial blood gas results. Adjusment of PaCO2 between 38-42 mmHg, 10 minutes of preoxygenation with FiO2 of 1.0 then disconnection of the patient from the ventilator. Continuous administration of 6 L/min O2 flow via a catheter into the tracheal tube. Arterial blood gas sampling and recording of vital parameters in every second minutes. Detection of any spontaneous respiratory movement by the apnoe test investigator or by EIT signals. Reconnection with respirator if there is any sign of spontaneous breathing effort or if there is no spontaneous breathing effort and the PaCO2 is over 60 mmHg. Recording of vital parameters. Recruitment manoeuvre (PEEP 20 cmH2O, pressure control 20 cmH20 for 40 minutes) then set up of the initial ventilator parameters. Terminal arterial blood gas results and vital parameters 5 minutes following the end of the recruitment manoeuvre. | Diagnostic Test: Apnea test, alveolar recruitment<br>* Alveolar recruitment following the phase of apnea testing<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| detection of spontaneous inspiration | Detection of absolute changes in impedance using EIT during apnea test, which may refer to spontaneous initiations of inspiration | 20 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gas exchange | Change in arterial partial pressure of oxygen (PaO2) (mmHg) following alveolar recruitment performed after apnea testing | 20 minutes | 
| Dynamic compliance | Change in dynamic compliance (ml/cmH2O) following alveolar recruitment | 20 minutes | 
| End expiratory lung impedance | Change in end expiratory lung impedance (EELI) (%) following alveolar recruitment | 20 minutes | 
| Center of ventilation | Change in center of ventilation (%) following alveolar recruitment | 20 minutes | 
| Lung perfusion | Changes in lung perfusion during the apnea phase (%) | 20 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Apnea testing, Electrical Impedance Tomography