Monitorings the Physiological Mechanism of Airway Pressure Release Ventilation in ARDS Patients by EIT

Study Overview
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Brief Summary
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Effects of airway pressure release ventilation on pulmonary ventilation, shunt and perfusion in patients with ARDS

Detailed Description
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Effects of airway pressure release ventilation on respiratory mechanisms including ventilation distribution, intrapulmonary shunt and V/Q match in lungs of ARDS evaluated by EIT at different time points.

Official Title
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Monitorings the Physiological Mechanism of Airway Pressure Release Ventilation(APRV) in Acute Respiratory Distress Syndrome (ARDS) Patients by Electrical Impedance Tomography(EIT)

Conditions
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Electrical Impedance Tomography, ARDS

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years old < age < 80 years old Diagnosed as moderate or severe ARDS according to the Berlin 2014 definition Predicted APRV mechanical ventilation for more than 72 hours Exclusion Criteria: Excluded if any of the following exclusion criteria are met: APRV contraindications such as pneumothorax, severe chronic obstructive pulmonary disease, severe asthma, intracranial hypertension Pregnant women Severe cardiac dysfunction (New York Heart Association class III or IV, acute coronary syndrome or sustained ventricular tachyarrhythmia), right heart enlargement due to chronic cardiopulmonary disease, cardiogenic shock or cardiac hand Refractory shock BMI>35

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| tidal volume distribution during APRV at 24 hours after APRV | we will use electrical impedance tomography(EIT) to monitor tidal volume distribution during APRV | 24 hours after APRV mechanical ventilation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| tidal volume distribution during APRV | tidal volume distribution electrical impedance tomography(EIT) during APRV | Before APRV mechanical ventilation and 2, 6, 12, 48, 72 hours after APRV mechanical ventilation | 
| Intrapulmonary shunt during APRV | Intrapulmonary shunt percent represented regions that were only perfused calculated as the slope of regional impedance-time curves after saline bolus injection evaluated by EIT | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| V/Q match | V/Q match is monitored by EIT | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| tidal volume(Vt) | Vt is the volume of air inhaled or exhaled per breath during mechanical ventilation | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Plateau pressure | Plateau pressure is the airway pressure at the end of inspiratory pause | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Positive end breath pressure | Positive end breath pressure(PEEP) is the airway pressure at the end of each breath which is set by clinicians | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Driving pressure(DP) | DP=Plateau pressure-PEEP | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Compliances(Cs) | Cs=DP/Vt | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Peak pressure | Peak pressure is the maximum pressure in the airway during ventilation occurs at the end of inspiration. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Mean pressure | Mean pressure is the average airway pressure over a number of breathing cycles | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Right ventricular area fractional change | Right ventricular area fractional change is a simple and repeatable ultrasound method for evaluating right ventricular function. Methods: The right ventricular end-diastolic area (RVEDA) and right ventricular end- systolic area (RVESA) were measured on the apical four-chamber section by two-dimensional ultrasound. RVAC=(RVEDA- RVESA)/RVEDA*100%. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Tricuspid annular systolic displacement (TAPSE) | TAPSE:Measurement method: TAPSE was measured on the four-chamber section of the apex of the heart by M-mode ultrasound. the sampling line was placed at the side wall of the tricuspid valve ring, parallel to the free wall of the right ventricle as far as possible, and the displacement of the tricuspid valve ring was measured from the end of diastole to the end of systole. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Tricuspid annular systolic S' velocity (TS') | TS' is an objective and accurate ultrasound technique for evaluating right ventricular function.Measurement method:The sample volume was applied to the free wall of the RV and the peak velocity of tricuspid annulus motion was measured in the four-chamber section of the apex by tissue doppler imaging (TDI). | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Right ventricular end-diastolic area/left ventricular end-diastolic area (RVEDA/LVEDA) | RVEDA/LVEDA a simple and repeatable ultrasound method for evaluating dynamics changes of right ventricular function.Methods: The right ventricular end-diastolic area (RVEDA) and left ventricular end-systolic area (LVEDA) were measured on the apical four-chamber section by two-dimensional ultrasound. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Pulmonary circulatory resistance (PVR) | Increased PVR can lead to deterioration of RV function.Pulse Doppler imaging (PWD) was used to obtain the pulmonary artery flow spectrum from the pulmonic valve on the short axial section of the parasternal great vessels. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| stroke volume index(SVI) | SVI is monitored by two-dimension ultrasound | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| cardiac index (CI) | The amount of blood pumped by the heart in liters per minute divided by the body surface area in square meters | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Heart rate(HR) | HR is one of the basic parameters of hemodynamics | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Systolic blood pressure(SBP) | SBP is one of the basic parameters of hemodynamics | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Mean arterial pressure (MAP) | MAP is one of the basic parameters of hemodynamics | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Cardiac output(CO) | The amount of blood expelled from one ventricle per minute | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Stroke volume | The amount of blood expelled from one ventricle during a single cardiac beat | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Arterial partial pressure of oxygen (PaO2) | PaO2 is one of the key indicators of patients' respiratory status which can be obtained from arterial blood gas analysis. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Arterial partial pressure of carbon dioxide(PaCO2) | PaCO2 is one of the key indicators of pulmonary ventilation which can be obtained from arterial blood gas analysis. | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| oxygenation index | oxygenation index=PaO2/fraction of inspired oxygen | Before APRV mechanical ventilation and 2, 6, 12, 24, 48, 72 hours after APRV mechanical ventilation | 
| Sequential Organ Failure Assessment score | The higher the Sequential Organ Failure Assessment(SOFA) score(0 24), the higher the disease risk factor and the higher the mortality rate | 2 hours within admission to ICU and 24 hours after inclusion in the study | 
| Acute Physiology and Chronic Health Evaluation score | The higher the Acute Physiology and Chronic Health Evaluation(APACHE II) score(0 71), the higher the disease risk factor and the higher the mortality rate. In particular, the accuracy of group patient prediction is high.In particular, the accuracy of group patient prediction is high. | 2 hours within admission to ICU and 24 hours after inclusion in the study | 
| Duration of ventilation after randomization | Time to mechanical ventilation in the ICU after randomization or time to mechanical ventilation after randomization until extubation or death | from the day of randomization to the day of extubation or the day of death,assessed up to 90 days | 
| Mortality at 28 days after randomization | Mortality at 28 days after randomization | 28 days after the beginning of randomization | 
| ICU length of stay | Duration of ICU stay after randomization until surviving transfer out of ICU | the whole period of stay in ICU from the day of randomization to the day of discharge from ICU or the day of death,assessed up to 90 days |