Assessment of Occult Lung Stress During Lung Protective Mechanical Ventilation

Study Overview
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Brief Summary
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The present study will utilize esophageal manometry to measure the presence and magnitude of persistent patient effort during lung protective ventilation, allowing identification and mitigation of occult lung stress.

Official Title
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Assessment of Occult Lung Stress During Lung Protective Mechanical Ventilation

Conditions
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Acute Respiratory Distress Syndrome

Intervention / Treatment
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* Other: Esophageal Catheter


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Intubated with a diagnosis of ARDS and expected to be ventilated for ≥ 48 hours Meets Berlin criteria for ARDS, with or without underlying chronic lung disease Triggering breaths on the ventilator Treating medical team agrees with patient participation Exclusion Criteria: Known or suspected esophageal abnormalities, craniofacial abnormalities, or upper GI bleed Shock that requires ≥ 2 vasopressors pH on arterial blood gas ≤7.25 Minute ventilation ≥ 14L/min Known or suspected pneumothorax, pneumomediastinum, and/or subcutaneous emphysema Severe ARDS with P/F ratio <60 Pregnancy Currently receiving extracorporeal membrane oxygenation (ECMO) therapy Decision to withhold life-sustaining treatment Patients who are not expected to survive for 24 hours Lack of informed consent

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: ARDS Patients Intubated on Mechanical Ventilation<br>ARDS patients in the ICU who are intubated on mechanical ventilation will be included. During ventilation, an esophageal catheter will be used to measure the esophageal pressure, which estimates pleural pressure at the level of the catheter. The esophageal catheter's position will be confirmed by a chest radiograph once inserted. The ventilator settings may be changed to see if these ventilator adjustments can reduce potential lung stress in ARDS patients. There is no set criteria for adjusting the ventilator settings based on the study device, but the goal would be to adjust the volume until the inspiratory effort measured by the catheter disappears so as to protect the patient. A one-to-two-hour study session will be performed for data collection. The esophageal catheter will be removed at the end of the study session or can be left in place for use as a feeding tube if needed for patient care. | Other: Esophageal Catheter<br>* Newly designed external monitor that will capture esophageal pressure from a proprietary nasogastric tube combined with simultaneous pressure, flow, and volume measurements from the ventilator tubing.<br>* Other names: PulmoTech Esophageal Pressure System (iEPS);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Transpulmonary Driving Pressure | Transpulmonary driving pressure is the pressure difference between the airway opening and pleural surface. It represents lung stress and is higher with increased spontaneous respiration and work of breathing. | Up to Hour 2 (Day 1) | 
| Driving Pressure | Driving pressure is defined as plateau pressure minus positive end-expiratory pressure (PEEP). Driving pressure during mechanical ventilation is directly related to stress forces in the lung. | Up to Hour 2 (Day 1) | 
| Work of Breathing (WOB) | WOB is the amount of energy or oxygen (O2) consumption needed by the respiratory muscles to produce enough ventilation and respiration to meet the metabolic demands of the body. | Up to Hour 2 (Day 1) | 
| Pressure-Time Product (PTP) | PTP is the product of the average inspiratory pressure (starting from the onset of effort) and the duration of inspiration. The PTP was developed to account for energy expenditures during the dynamic and isometric phases of respiration. | Up to Hour 2 (Day 1) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung Compliance (C, l) | Lung compliance is calculated as the tidal volume divided by the difference of transpulmonary pressure at end inspiration minus transpulmonary pressure at PEEP: (C, l) = tidal volume/(transpulmonary pressure at end inspiration - transpulmonary pressure at PEEP). Expressed in (ml/cmH2O). | Up to Hour 2 (Day 1) | 
| Chest Wall Compliance (C, cw) | Chest wall compliance is calculated as the tidal volume divided by the difference of esophageal pressure at end inspiration minus esophageal pressure at PEEP: (C, cw) = tidal volume/(esophageal pressure at end inspiration - esophageal pressure at PEEP). Expressed in (ml/cmH2O). | Up to Hour 2 (Day 1) | 
| Respiratory System Compliance (C, rs) | Respiratory System Compliance is calculated as the tidal volume divided by the difference of the airway pressure at end inspiration minus airway pressure at PEEP: (C, rs) = tidal volume/(airway pressure at end inspiration - airway pressure at PEEP). Expressed in (ml/cmH2O). | Up to Hour 2 (Day 1) | 
| Oxygen Saturation | Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin in the blood. | Up to Hour 2 (Day 1) | 
| PaO2/FiO2 (P/F) Ratio | The P/F ratio is the arterial partial pressure of oxygen (PaO2) divided by the inspired oxygen concentration (FiO2). | Up to Hour 2 (Day 1) |