Gas Exchange and Cardiovascular Kinetics of Regulation - Effects of Short Term Changes in Gravity

Study Overview
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Brief Summary
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The regulation of the cardiovascular respiratory system after changing environmental conditions or changes in work rates are essential for cognitive as well as physical functioning. For decades, it is known that high level of headward acceleration (+Gz) impairs cardiovascular function that may cause loss of consciousness. Some anti-g maneuvers, such as muscle contraction of the lower extremities and buttocks or intermittent exhalation on exertion (i.e., exhalation against a closed airway) have been proved to increase tolerance to high +Gz. Main objective of this experiment is to investigate the effects of anti-g maneuvers on cardiovascular and respiratory tolerance to the push-pull-effect. Cardiovascular and respiratory functions will be evaluated with the following parameters: heart rate, stroke volume, cardiac output, blood pressure, oxygen uptake, carbon dioxide output, ventilation, breathing frequency, body core temperature. Electromyography (EMG) will not be a judgment criteria but will be used to check the quality of 'muscle contraction' anti-g maneuver. The main hypothesis is that anti-g maneuvers will increase cardiovascular and respiratory tolerance to the push-pull effect, especially when they are combined.

Official Title
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Gas Exchange and Cardiovascular Kinetics of Regulation - Effects of Short Term Changes in Gravity

Conditions
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Healthy Volunteers

Intervention / Treatment
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* Other: anti-g maneuvers


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers (men or women) Aged from 20 to 65 Affiliated to a Social Security system and, for non-French resident, holding a European Health Insurance Card (EHIC) Who accepted to take part in the study Who have given their written stated consent Who has passed a medical examination similar to a standard aviation medical examination for private pilot aptitude (JAR FCL3 Class 2 medical examination). There will be no additional test performed for subject selection. Subjects will be staff member of the team or of other teams participating in the parabolic flight campaign. Exclusion Criteria: Person who took part in a previous biomedical research protocol, of which exclusion period is not terminated Treated or non-treated arterial hypertension Smoker Asthma Respiratory bacterial or viral infection Pregnant women

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 65 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

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: anti-g maneuvers<br>Before the first parabola, pulmonary function will be evaluated. Then during each weightlessness period the subject will be instructed either to stay at rest (control condition) or to perform anti-g maneuvers (4 times each): intermittent exhalation on exertion, lower limbs and abdomen muscular contraction, combined maneuver ('intermittent exhalation on exertion' + 'muscle contraction'). Before, the exhalation on exertion, the subject will close the airway after the mouthpiece by pushing on a button actuating a pneumatic valve. Each subject will be tested during 15 parabola where the anti-g maneuvers will be performed in randomized order. After the 15th parabola, pulmonary function will be again evaluated. | Other: anti-g maneuvers<br>* investigate the effects of anti-g maneuvers on cardiovascular and respiratory tolerance to the push-pull-effect.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| heart rate | during 15 parabola | baseline | 
| cardiac output with ECG | during 15 parabola | baseline | 
| blood pressure | during 15 parabola | baseline | 
| oxygen uptake measured with a spirometer | during 15 parabola | baseline | 
| carbon dioxide output measured with a spirometer | during 15 parabola | baseline | 
| ventilation measured with a spirometer | during 15 parabola | baseline | 
| breathing frequency measured with a spirometer | during 15 parabola | baseline | 
| body core temperature measured with 2 temperature sensors - one on forehead and the other one chest | during 15 parabola | baseline |