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| Name | Class |
|---|---|
| National Space Biomedical Research Institute | OTHER |
| DLR German Aerospace Center | OTHER |
| The University of Texas Health Science Center, Houston | OTHER |
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The purpose of this study is to study the effects of carbon dioxide combined with head down tilt on cerebral physiology and anatomy. This paradigm will help establish a ground-based analog for spaceflight, and also evaluate the ability of non-invasive devices to monitor brain physiology.
Many of the long duration astronauts develop visual changes, associated with neuroophthalmological abnormalities suggesting elevated intracranial pressure. There is currently no suitable ground based analog to simulate these changes on Earth, or a standard methodological approach to monitoring the combined effects of head down tilt and atmospheric carbon dioxide. Given that carbon dioxide and cephalad fluid shifting are known factors in spaceflight, we sought to evaluate an approach to monitoring these effects in healthy subject in a ground based analog on Earth.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Atmosphere 1 - Ambient air | Active Comparator | First, the subjects will have 1 baseline day in the upright body position. This will be followed by 28 hours of head down tilt body position and ambient air at sea level, followed by 2 hour exposure of 3% carbon dioxide inhalation. |
|
| Atmosphere 2 - 0.5% CO2 | Experimental | First, the subjects will have 1 baseline day in the upright body position. This will be followed by 28 hours of head down tilt body position and air with 0.5% carbon dioxide, followed by 2 hour exposure of 3% carbon dioxide inhalation. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 0.5% CO2 | Other | The subjects will be randomized to breath 0.5% carbon dioxide during one of the -12 degree head down tilt body position periods in crossover design |
|
| Measure | Description | Time Frame |
|---|---|---|
| Changes in cerebral blood flow: Transcranial doppler | Transcranial Doppler derived measurements of mean cerebral blood flow velocity | 24 and 48 hours from baseline measurements |
| Changes in intracranial volume | Cerebrotech monitor derived intracranial fluid volume changes (percentage change) | 24 and 48 hours from baseline measurements |
| Changes in intracranial pressure | Vittamed ICP meter derived intracranial pressure (mmHg) | 24 and 48 hours from baseline measurements |
| Changes in cognitive function | Cognition battery score (max 1000): tests multiple cognitive domains including spatial memory, psychomotor processing speed, facial emotional recognition | 24 and 48 hours from baseline measurements |
| Changes in cerebral blood flow: cFLOW | cFLOW derived changes in cerebral blood flow index | 24 and 48 hours from baseline measurements |
| Measure | Description | Time Frame |
|---|---|---|
| Tolerability of combined -12 head down tilt and 0.5% carbon dioxide | Assess safety outcomes: tolerance of condition through duration of study and number of adverse events | Within 48 hours from baseline |
| Changes in intraocular pressure |
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Inclusion Criteria:
Exclusion Criteria:
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| ID | Term |
|---|---|
| D052638 | Particulate Matter |
| ID | Term |
|---|---|
| D045424 | Complex Mixtures |
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| University of Pennsylvania |
| OTHER |
| Harvard University | OTHER |
| University of Cologne | OTHER |
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| ambient air | Other | The subjects will be randomized to breath ambient air during one of the -12 degree head down tilt body position periods in crossover design |
|
iCare derived intraocular pressure measurements from both eyes (mmHg)
| 24 and 48 hours from baseline measurements |
| Changes in pulmonary mechanics | minute ventilation, respiratory rate and vital capacity | 24 and 48 hours from baseline measurements |
| Changes in internal jugular vein volumes | Ultrasound derived measure of right internal jugular vein cross sectional areas | 48 hours from baseline measurements |
| Changes in peripheral arterial vasoreactivity | Ultrasound Doppler Measurement of arterial diameter and flow (cm/sec) after transient cuff occlusion of brachial artery | 48 hours from baseline measurements |
| Changes in cardiac hemodynamics | Assessment of cardiac output, stroke volume, heart rate, blood pressure | 48 hours from baseline measurements |
| Changes in olfactory threshold | Sniffin' sticks threshold testing for phenyethyl alcohol | 24 and 48 hours from baseline measurement |
| Changes in pulmonary gas exchange | changes in arterial pH and partial pressure CO2 | 24 and 48 hours from baseline measurements |