Stress Index to Individualize Mechanical Ventilation in ARDS

Study Overview
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Brief Summary
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Acute respiratory distress syndrome (ARDS) is a widely prevalent and morbid disease for which the current standard treatment is supportive care and avoidance of complications with lung-protective ventilation. Lower-tidal volume ventilation has been largely accepted as a means of lung protective ventilation, but the mechanism for its effectiveness is not yet clear, and debate remains as to how best to choose positive end-expiratory pressure (PEEP). Reduction in driving pressure (plateau pressure minus PEEP) has been suggested as a possible means to minimize ventilator-induced lung injury. This protocol aims to identify the range of safe paired-settings of PEEP and tidal volume, with selection guided by driving pressure and the stress index, a tool to recognize potential lung hyperinflation during mechanical ventilation.

Official Title
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Right-Sizing Tidal Volume in ARDS: Using the Stress Index to Optimize Mechanical Ventilation to Individual Respiratory Mechanics

Conditions
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Acute Respiratory Distress Syndrome

Intervention / Treatment
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* Procedure: Recruitment Maneuver with PEEP and Tidal Volume Optimization


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Admitted to the Intensive Care Unit Receiving invasive mechanical ventilation via endotracheal or tracheostomy tube Presence of ARDS by Berlin Criteria (acute onset bilateral pulmonary infiltrates incompletely explained by left heart failure together with a PaO2/FiO2 of <300 or SpO2/FiO2 <315) Exclusion Criteria: Inability to obtain surrogate consent Presence of specified comorbidities: pregnancy pre-existing severe chronic obstructive pulmonary disease, defined as FEV1 documented < 1L or baseline hypercapnia cerebral edema known intra-cranial abnormality acute coronary syndrome Endotracheal or tracheostomy cuff leak Chest tube with persistent air leak Severe hemodynamic instability (defined as attending judgment that the patient is unable to safely tolerate ventilator manipulations) Presence of spontaneous respiratory activity as evidenced by examination of the ventilator waveform tracing Intrinsic PEEP of > 5 cmH2O Assessment of study staff or patient's attending physician that the patient would not be a good study participant

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: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention Arm<br> | Procedure: Recruitment Maneuver with PEEP and Tidal Volume Optimization<br>* A staircase recruitment maneuver will be performed on pressure control ventilation followed by a decremental PEEP trial. During the decremental PEEP trial inspiratory tidal volumes will be varied at each step between 3 ml/kg and 10 ml/kg predicted body weight while recording the continuous pressure and flow tracings from the mechanical ventilator. With each PEEP and tidal volume combination, end expiratory and end-inspiratory plateau pressure and stress index will be assessed. At the completion of the decremental PEEP trial, the patient will be returned to ARDSnet-recommended ventilator settings.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of ARDSnet-optimized and protocol-optimized tidal volume | Mean absolute difference between tidal volume in cc/kg PBW prescribed by ARDSnet settings on ARDSnet PEEP versus maximal protective tidal volume defined by stress index <1.05 at the ARDSnet PEEP on experimental protocol. | Completion of the study intervention, less than 1 day | 
| Comparison of ARDSnet-optimized and protocol-optimized driving pressure | Mean difference in driving pressure prescribed by ARDSnet settings versus at lowest measured possible driving pressure that achieves equivalent minute ventilation as ARDSnet table with respiratory rate < or = 35 per minute and SI <1.05. | Completion of the study intervention, less than 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of ARDSnet-optimized and protocol-optimized PEEP | Mean absolute difference between safest PEEP as determined by experimental protocol with tidal volume of 6 mL/kg PBW (defined as the PEEP at which 6 mL/kg PBW yields the lowest driving pressure with a SI <1.05) versus the PEEP established by ARDSnet table. | Completion of the study intervention, less than 1 day | 
| Comparison of ARDSnet-optimized and protocol-optimized elastance | Mean difference in elastance prescribed by ARDSnet settings versus at lowest measured possible elastance achieving equivalent minute ventilation as ARDSnet table with respiratory rate < or = 35 per minute. | Completion of the study intervention, less than 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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mechanical ventilation, respiratory mechanics, acute respiratory distress syndrome, positive end-expiratory pressure, tidal volume