ARDS Esophageal Balloon Pressure Changes With Positioning Study

Study Overview
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Brief Summary
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The use of esophageal balloon catheters, which use esophageal pressure as a surrogate measurement for transpleural pressure, shows promise in improving outcomes of patients with severe acute respiratory distress syndrome (ARDS) requiring mechanical ventilator. The investigators hope to measure changes in in transpleural pressures in patients undergoing treatment with mechanical ventilation while switching from the supine, upright (head of bed >30 degrees), and prone positions. The goal will be to measure the changes in chest wall and lung compliance in mechanically ventilated patients with changes in position.

Detailed Description
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The use of esophageal balloon catheters shows promise in improving outcomes of patients with severe ARDS. The estimation of pleural pressure (Ppl) has been validated in the upright position in humans with few studies commenting on the changes in supine positioning and almost none on prone positioning aside from radiographic analysis. An abstract presented at the annual American Thoracic Society meeting recently reported a series of 18 patients undergoing spinal surgery. In this population of patients without ARDS, esophageal pressure (Pes) decreased when shifting from supine to prone positioning. This suggests that transpleural pressure (PtmL) would be increased at a given airway pressure. The investigators hope to measure changes in PtmL in patients undergoing treatment with mechanical ventilation while switching from the supine, upright (head of bed >30 degrees), and prone positions. The esophageal balloon catheter will be placed using standard techniques and secured with tape to the patients' nares during changes in positioning. The goal will be to measure the changes in chest wall and lung compliance in mechanically ventilated patients with changes in position.

Official Title
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Assessing Pleural Pressure Changes Between Supine, Upright and Prone Mechanical Ventilation

Conditions
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ARDS, Respiratory Failure

Intervention / Treatment
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* Device: Esophageal balloon catheter


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age at least 18 years old, need for mechanical ventilation, moderate or severe ARDS, and the ability to tolerate prone positioning. Exclusion Criteria will be patients who: are deemed too ill by their clinicians to be included in the study have esophageal or nasopharyngeal pathology (such as tumors, sinusitis, epistaxis, ulcerations, recent surgery or bleeding varices) preventing insertion of the esophageal balloon catheter diverticulitis bronchopulmonary fistula solid-organ transplantation history of difficult intubation or airway management or contraindications to prone positioning (per the UNC Medical Intensive Care Unit Pronation Therapy protocol, attached)

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Esophageal balloon catheter placement<br>This is the primary and only arm of the study in which acute respiratory distress syndrome patients will have an esophageal balloon catheter placed with pressures recorded in the supine, upright and prone positions | Device: Esophageal balloon catheter<br>* Measurements obtained from mechanically ventilated patients with ARDS in the supine, upright and prone positions<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Esophageal pressure measurements from upright to prone position | Obtained from esophageal balloon catheter measurements in prone and upright positions | Measurements will be obtained in the baseline upright position and repeated after about 4 hours in the prone position. | 
| Change in Esophageal pressure measurements from upright to supine position | Obtained from esophageal balloon catheter measurements in upright and supine positions | The patient is upright at baseline where measurements will be obtained. About 5 minutes will be spent in the supine position. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Transmural pressure measurements from upright to prone position | Obtained from combination of esophageal balloon catheter measurements and mechanical ventilator in upright and prone positions | Measurements will be obtained in the baseline upright position and repeated after about 4 hours in the prone position. | 
| Change in Transmural pressure measurements from upright to supine position | Obtained from esophageal balloon catheter measurements in upright and supine positions | The patient is upright at baseline where measurements will be obtained. About 5 minutes will be spent in the supine position. | 
| Change in Airway pressure measurements from upright to prone position | Obtained from mechanical ventilator in prone and upright positions | Measurements will be obtained in the baseline upright position and repeated after about 4 hours in the prone position. | 
| Change in Airway pressure measurements from upright to supine position | Obtained from mechanical ventilator in supine and upright positions | The patient is upright at baseline where measurements will be obtained. About 5 minutes will be spent in the supine position. |