Advanced Gravitational Physiology the Lung Under High-G Acceleration

Study Overview
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Brief Summary
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This is a study of advanced lung physiology in altered gravitational conditions, consisting of respiratory measurements in healthy volunteers during high G acceleration on a long-arm human centrifuge.

Detailed Description
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The lung is highly gravity-dependent - it has little actual tissue mass and deforms under its own weight. This is relevant to astronauts in space, but is actually much more broadly important to life on Earth. Every time we change our posture - for example from lying to standing - the direction in which gravity acts across the lung changes. These postural effects can become clinically important in critically ill patients. Currently there is debate in the scientific world about how gravity actually influences lung function, and how it interacts with other factors such as the anatomical structure of the airways and blood vessels of the lung. New technology developed by researchers at the University of Oxford now has the potential to help answer some of these questions. This device uses a technique called laser absorption spectroscopy to make measurements of breathing gases that are much more accurate than previous techniques - it is able to count the number of oxygen, carbon dioxide and water vapour molecules in and out while a person breathes. A non-invasive 15-minute breathing test with this technology provides information on the distributions of airflow and blood flow in the lungs, and it has been deployed successfully in the operating theatre and in intensive care units. This study aims to make comprehensive measurements of lung physiology under altered gravitational conditions and develop the technology and measurement techniques for possible future use in microgravity. This will include measurements of oxygen and carbon dioxide from the laser gas analyser (and measures of lung inhomogeneity obtained from these), lung mechanics and breathing drive.

Official Title
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Advanced Gravitational Physiology the Lung Under High-G Acceleration

Conditions
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Respiratory Physiology

Intervention / Treatment
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* Other: High G acceleration on a long-arm human centrifuge


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy volunteer who has provided informed consent Exclusion Criteria: any significant medical problem, as documented extensively in the study ethics documentation.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 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: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Centrifuge study<br>High G acceleration on a long-arm human centrifuge | Other: High G acceleration on a long-arm human centrifuge<br>* Gx (chest-to-back) and Gz (head-to-toe)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung inhomogeneity index | The lung inhomogeneity index is the standard deviation for the natural logarithm of the standardised lung compliance, equivalent to the standard deviation for the natural logarithm of the ratio between fractional lung compliance and fractional alveolar volume of the lung units. It is determined using the respiratory data obtained by molecular flow sensing using the laser gas analyser. | Determined over a 15-minute multi-breath washout at 3 G on the centrifuge | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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respiratory, physiology, gravity