Effect of Hyperoxia and Hypergravity on Lung Ventilation and Perfusion

Study Overview
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Brief Summary
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The primary aim of this project is to get further knowledge on the effects of + Gz accelerations and hyperoxia on lung ventilation in humans. The secondary aim is to study lung perfusion and cardiovascular function in these conditions.

Detailed Description
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Experiments were conducted in a human centrifuge. The protocol aimed at mimicking a routine peacetime flight in combat aircraft, and included 10-min exposure to +1.4 - +3.5 Gz. Subjects were exposed three times to this sequence, breathing air, 44.5% O2 or 100% O2. Ten volunteers wearing anti-G trousers participated in the study. The Ethics Committee Ile-de-France III and the French National Agency for Drug Safety (ANSM) approved the protocol (number 2009-A01092-55). Three different imaging techniques, electrical impedance tomography (EIT), pulmonary ultrasound and chest SPECT/CT were used and compared. EIT enabled ventilation monitoring in the human centrifuge, whereas pulmonary ultrasound and SPECT/CT gave functional and topographical information before and after exposure to +Gz accelerations. EIT analysis focused on regional ventilation, SPECT on global lung ventilation and perfusion, CT on the presence of atelectasis, and pulmonary ultrasound analysis looked for comet tails in 64 chest areas. Arterial blood pressure was recorded continuously by finger photoplethysmography. Cardiac output and stroke volume were computed from these recordings, using three different algorithms. Echocardiography was used as reference non-invasive technique for stroke volume determination and performed before and after exposure to +Gz accelerations.

Official Title
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Influence of Hyperoxia and Hypergravity on Pulmonary Ventilation and Perfusion

Conditions
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Atelectasis

Intervention / Treatment
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* Other: hypergravity
* Other: gas mixture


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: normal lung function checked by pulmonary function tests Part 1 exclusion Criteria: past medical history of heart or lung disease current medical treatment for heart or lung disease smoking bad tolerance to +Gz accelerations (G-induced loss of consciousness, motion sickness) Part 2 exclusion criteria: past medical history of heart or lung disease current medical treatment for heart or lung disease smoking The use of medication for hypertension asymmetric values of left/right humeral arterial blood pressure significant echocardiographic abnormalities or bad echogenicity bad tolerance to +Gz accelerations (G-induced loss of consciousness, motion sickness)

Ages Eligible for Study
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Minimum Age: 25 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

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: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: ventilation<br>hypergravity gas mixture | Other: hypergravity<br>* 1hr sitting rest followed by 10 min of hypergravity (2 centrifuge runs)<br>Other: gas mixture<br>* breathing air, 44.5%O2 or 100%O2<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in regional ventilation distribution | per lobe and per quadrant at 5th intercostal space level | baseline, 2hrs 30min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in regional pulmonary perfusion | per lobe and per quadrant at 5th intercostal space level | baseline, 2hrs 30min | 
| cardiac output (L/min) | echocardiography (sub-aortic diameter), photoplethysmography (Liljestrand, systolic area and Windkessel algorithms) | 2hrs | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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human centrifuge, oxygen, imaging, stroke volume, lung