EIT Assessment of Lung Volume and Tidal Distribution: A Comparison of Non-Invasive Ventilation Devices

Study Overview
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Brief Summary
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This study is being done to further the investigators' knowledge of the EIT system and to see if measures between two non-invasive ventilation systems routinely used clinically are equivalent.

Detailed Description
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Mechanical ventilation is life-saving technology but it can also inadvertently induce lung injury and increase morbidity and mortality. There currently is not an easy method of assessing the impact ventilator settings have on the degree of lung inflation. Computed tomography (CT), the gold standard for visually monitoring lung function, can provide detailed regional information of the lung. Unfortunately, it necessitates moving critically ill patients to a special diagnostic room and involves exposure to radiation like an X-ray. A technique introduced in the 1980's, electrical impedance tomography (EIT), can non-invasively provide similar monitoring of lung function, and without the exposure to radiation. This imaging technique applies small alternating currents of electricity to surface electrodes to construct cross-sectional images of the lung. Over that past several decades EIT has moved from the research lab to commercially available devices that are used at the bedside. EIT has also been applied to study the effects of various devices used to provide non-invasive ventilation. EIT may prove useful to optimally adjust non-invasive ventilation settings to improve ventilation and oxygenation. One such EIT system is manufactured by Draeger Medical. It is available in Europe and Canada but is not yet FDA approved for use in the United States. This study is being done with healthy volunteers to further the investigators' knowledge of the EIT system and to see if measures between two non-invasive ventilation systems routinely used clinically are equivalent. As this is a preliminary study looking at the EIT system vs 2 other devices, outcomes measures may be modified as the study progresses.

Official Title
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EIT Assessment of Lung Volume and Tidal Distribution: A Comparison of Non-Invasive Ventilation Devices

Conditions
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Spontaneous Ventilation

Intervention / Treatment
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* Device: noninvasive positive pressure ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18 years or older Exclusion Criteria: Use of a cardiac pacemaker, an implantable cardioverter-defibrillator (ICD) or any other active implants

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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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Respironics V-60, then Draeger V500<br>Testing by applying noninvasive positive pressure ventilation (NPPV) via two different bilevel positive airway pressure (BiPAP) devices . Arm one applies the Respironics V-60, then the Drager V-500. | Device: noninvasive positive pressure ventilation<br>* Application of various levels of positive pressure<br>|
| Active Comparator: Draeger V500, then Respironics V-60<br>Testing by applying noninvasive positive pressure ventilation (NPPV) via two different bilevel positive airway pressure (BiPAP) devices . Arm two applies the Drager V-500, then the Respironics V-60. | Device: noninvasive positive pressure ventilation<br>* Application of various levels of positive pressure<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Global Tidal Variation (TID) | TID is the distribution of ventilation for a breath averaged over a defined section, the entire lung. TID is analogous to the tidal volume. Baseline is defined to be 100% and other measures are in comparison to baseline (eg, a value of 102 represents a 2% increase from baseline). | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Regional Tidal Variation: Dorsal | Distribution of ventilation for a breath averaged over a defined section, the dorsal lung regions. Reflects the percent of tidal volume distributed to that area. | 1 day | 
| Regional Tidal Variation: Ventral | Distribution of ventilation for a breath averaged over a defined section, the ventral lung regions. Reflects the percent of tidal volume distributed to that area. | 1 day | 
| Global Change in End-expiratory Lung Impedance (EELI) | EELI is the impedance at the end of tidal variation, or end-expiration. EELI reflects the end-expiratory lung volume (EELV); thus an increase in EELI represents and increase in lung volume. The change in EELI that the electrical impedance tomography (EIT) device (Pulmovista, Drager) provides is the percent difference between the EELI of a given period and the EELI during a baseline or reference period. Positive or negative percent change suggests an increase or decrease in EELI and presumably EELV by a similar percentage. The baseline measurements used here were taken breathing air and no pressures applied, while the other measurements were taken with varying levels of pressure applied. By definition, baseline is assigned the value of 0%, by the EIT device. While it would be helpful to have the actual numbers for the baseline impedance values, this data was not provided by the EIT device. | 1 day | 
| Regional Change in EELI: Dorsal | EELI is the impedance at the end of tidal variation, or end-expiration. EELI reflects the end-expiratory lung volume (EELV); thus an increase in EELI represents and increase in lung volume. The change in EELI that the electrical impedance tomography (EIT) device (Pulmovista, Drager) provides is the percent difference between the EELI of a given period and the EELI during a baseline or reference period. Positive or negative percent change suggests an increase or decrease in EELI and presumably EELV by a similar percentage. The baseline measurements used here were taken breathing air and no pressures applied, while the other measurements were taken with varying levels of pressure applied. By definition, baseline is assigned the value of 0%, by the EIT device. While it would be helpful to have the actual numbers for the baseline impedance values, this data was not provided by the EIT device | 1 day | 
| Regional Change in EELI: Ventral | EELI is the impedance at the end of tidal variation, or end-expiration. EELI reflects the end-expiratory lung volume (EELV); thus an increase in EELI represents and increase in lung volume. The change in EELI that the electrical impedance tomography (EIT) device (Pulmovista, Drager) provides is the percent difference between the EELI of a given period and the EELI during a baseline or reference period. Positive or negative percent change suggests an increase or decrease in EELI and presumably EELV by a similar percentage. The baseline measurements used here were taken breathing air and no pressures applied, while the other measurements were taken with varying levels of pressure applied. By definition, baseline is assigned the value of 0%, by the EIT device. While it would be helpful to have the actual numbers for the baseline impedance values, this data was not provided by the EIT device | 1 day |