The Brain and Lung Interaction (BALI) Study

Study Overview
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Brief Summary
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The purpose of this study is to understand the relationship between intracranial pressure and airway pressures during mechanical ventilation. This study is a single-center, prospective cohort study to be conducted at Beth Israel Deaconess Medical Center. The investigators will recruit patients with severe brain injury (GCS 8 or less) who receive intracranial pressure monitoring and mechanical ventilation as part of their routine medical care. The primary endpoint is the change in intracranial pressure as a function of positive end-expiratory pressure. There is only one study encounter with safety monitoring for up to 24 hours after. No additional follow up is required.

Official Title
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The Effect of Positive End Expiratory Pressure on Intracranial Pressure: The Brain and Lung Interaction (BALI) Study

Conditions
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Intracranial Pressure, Mechanical Ventilation, Brain Injuries

Intervention / Treatment
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* Other: PEEP Titrated Mechanical Ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Patients with severe brain injury (GCS 8 or less) who receive both mechanical ventilation and intracranial pressure monitoring as part of their standard medical care will be considered eligible. Exclusion Criteria: Patients with esophageal varices Patients with esophageal trauma Patients with recent esophageal surgery Patients with coagulopathy (Platelets < 80k or INR> 2 ) Other contraindication for esophageal manometry Patients who are receiving PEEP greater than 15 cmH2O within 24 hours prior to enrollment Intracranial hypertension (defined as ICP greater than 20 mmHg) within 48 hours prior to enrollment Decompressive hemi-craniectomy Cessation Criteria: Study related ventilator adjustments and measurements will be stopped at any point during the intervention and ventilator settings will be returned to the pre-intervention settings under the following conditions: If ICP increases above 20mmHg, regardless of the duration of the event. If systolic blood pressure decreases below 90mmHg, regardless of the duration of the event. If systolic blood pressure increases above 180mmHg, regardless of the duration of the event.

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: PEEP Titration Arm<br> | Other: PEEP Titrated Mechanical Ventilation<br>* Subjects will receive a sequential, step-wise increase in positive end-expired pressure from 5 cmH2O to 15 cmH2O and back down to 5 cmH20. Pleural pressure and intracranial pressure will be measured at each increment. PEEP will be increased by increments of 5 cmH2O. The physiologic measurements will be obtained at regular intervals (within 5 minutes at each PEEP level) throughout the PEEP titration period. The mode of mechanical ventilation (pressure or volume control), inspiratory time and fraction of inspired oxygen (FIO2) will be determined by the critical care team caring for the patient. In the event that PEEP is set > 5 cmH2O, measurements will be obtained from that starting point and increased to a maximum of 15 cmH2O. At the completion of the study patients will be returned to the PEEP level they were on prior to titration of the ventilator.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in intracranial pressure | The primary endpoint is the change in intracranial pressure as a function of positive end-expiratory pressure. | Change from baseline to 20 minutes |