Ventilation and Perfusion in the Respiratory System

Study Overview
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Brief Summary
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Respiratory failure occurs when the lung fails to perform one or both of its roles in gas exchange; oxygenation and/or ventilation. Presentations of respiratory failure can be mild requiring supplemental oxygen via nasal cannula to more severe requiring invasive mechanical ventilation as see in acute respiratory distress syndrome (ARDS).It is important to provide supportive care through noninvasive respiratory support devices but also to minimize risk associated with those supportive devices such as ventilator induced lung injury (VILI) and/or patient self-inflicted lung injury (P-SILI). Central to risk minimization is decreasing mechanical stress and strain and optimizing transpulmonary pressure or the distending pressure across the lung, minimizing overdistention and collapse. Patient positioning impacts ventilation/perfusion and transpulmonary pressure. Electrical impedance tomography (EIT) is an emerging technology that offers a noninvasive, real-time, radiation free method to assess distribution of ventilation at the bedside. The investigators plan to obtain observational data regarding distribution of ventilation during routine standard of care in the ICU, with special emphasis on postural changes and effects of neuromuscular blockade, to provide insight into ventilation/perfusion matching, lung mechanics in respiratory failure, other pulmonary pathological processes.

Official Title
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Ventilation and Perfusion in the Respiratory System

Conditions
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Respiratory Failure, Respiratory Distress Syndrome, Adult, Critical Illness, Pulmonary Disease, Ventilator-Induced Lung Injury

Intervention / Treatment
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* Device: Electrical Impedance tomography
* Other: Lung mechanics and gas exchange


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years or older admitted to UC San Diego La Jolla or Hillcrest Campus Intensive Care Units Patient requiring supplemental oxygen (including but no limited to nasal cannula, high flow devices, noninvasive positive pressure ventilation or mechanical ventilation Exclusion Criteria: <18 years Chest wall, anatomical, physical abnormalities, skin integrity issues precluding placement of electrode belt in direct contact with skin Patient is too unstable to position the belt/electrodes or tolerate head of bed changes Confirmed or suspected intracranial bleed, stroke, edema Active implants (i.e. implantable electronic devices such as pacemakers, cardioverter defibrillators, neurostimulators) or if device compatibility is in doubt Pregnant or lactating patients as safety and efficacy for use of EIT in such cases has not been verified

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 |
| --- | --- |
| Respiratory failure<br> | Device: Electrical Impedance tomography<br>* Patients will be monitored with electrical impedance tomography during routine care with special attention to effects of neuromuscular blockade and postural changes.<br>Other: Lung mechanics and gas exchange<br>* Patient lung mechanics and gas exchange will be monitored during routine clinical care, with specific attention to postural changes and use of neuromuscular blockade.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Distribution of ventilation | Regional ventilation distribution differences measured through electrical impedance tomography (EIT) | change from baseline at 15 minutes and 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung mechanics | Lung compliance | Baseline, then at 15 minutes and 1 hour | 
| Oxygenation | Oxygen saturation measured by pulse oximetry (SpO2) and fraction of inspired oxygen (FiO2) as well as arterial blood gas partial pressure of oxygen (PaO2). Results will be reported as either PaO2/FiO2 ratio or SpO2/FiO2 ratio (depending on availability of arterial blood gas measurements) | Up to 48 hours | 
| Blood Gas Partial Pressure of Carbon Dioxide (PaCO2) (mmHg) | Partial pressure of carbon dioxide (PaCO2) (mmHg) | Up to 48 hours | 
| Blood Gas pH | Blood Gas pH | Up to 48 hours |