Atelectasis Formation: Role of Positive Pressure Breathing, Hyperoxia, and Hypobaria

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

NA

Total Enrollment

80 participants

Study Classification

INTERVENTIONAL

Study Start Date

2015-09-14

Study Completion Date

2020-01-01

Brief Summary

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The primary aim of this project is to get further knowledge of the physiology of flight atelectasis and its prevention. We seek to: 1) assess whether low levels of positive pressure breathing can prevent atelectasis formation in humans during exposure to hyperoxia and +Gz-accelerations. 2) get further knowledge on the effects of hypobaria on regional ventilation and perfusion.

A secondary aim is to evaluate the effect of anti G-trouser inflation on ventilation and regional perfusion.

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Detailed Description

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The effect of positive pressure breathing on lung function is being studied, when applied during exposure to hyperoxia and +Gz-accelerations. Focus is on lung tissue compression, ventilation and regional perfusion. In addition, the influence of hypobaria on these parameters is assessed.

This study is conducted in accordance with the amended Declaration of Helsinki. The Ethics Committee Ile-de-France III (ref. 3274) and the French National Agency for Drug Safety ANSM have approved the protocol (ref. ID RCB 2015-A00485-44 and ANSM 151046B-32).

Primary aim, item 1: Experiments are conducted in a human centrifuge. The protocol mimics a routine peacetime flight in combat aircraft, and includes 1hr05 min at +1Gz followed by 10-min exposure to +1.4 to +3.5Gz . Subjects are exposed three times to this sequence, breathing at positive pressure levels of 0, 5 or 10 hPa. Two groups of sixteen healthy male non-smoking volunteers, wearing anti-G trousers, are studied and compared: group 1 breathes air, group 2 100% O2.

Primary aim, item 2: Experiments are conducted in a hypobaric chamber. Sixteen healthy male non-smoking volunteers are exposed to four conditions: 0 or 15,000 ft altitude, breathing air or 100%O2. Protocol duration is 1h15min. Positive breathing pressure can be applied depending on the results of the experiments of item 1.

Secondary aim: Experiments are conducted in a human centrifuge. Sixteen healthy male non-smoking volunteers are exposed to four conditions: uninflated or inflated anti-G trousers (175 hPa), +1 or +3.5 Gz for 3 min.

Conditions

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Pulmonary Atelectasis

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Two arms are studied, breathing air or 100%O2. In each arm, subjects are studied at two occasions: with and without positive pressure breathing. These occasions are randomized.

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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100%O2 breathing

Primary aim, item 1

Group Type EXPERIMENTAL

+Gz accelerations and positive pressure breathing

Intervention Type OTHER

Air breathing

Primary aim, item 1

Group Type EXPERIMENTAL

+Gz accelerations and positive pressure breathing

Intervention Type OTHER

Interventions

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+Gz accelerations and positive pressure breathing

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* normal lung function checked by pulmonary function tests.
* normal ECG
* normal clinical examination

Exclusion Criteria

* smoking
* myopia
* past medical history of heart or lung disease
* current medical treatment for heart or lung disease
* past medical history of back pain or spine trauma or disease
* otitis
* bad tolerance to +Gz accelerations (G-induced loss of consciousness, motion sickness)
* claustrophobia in the centrifuge gondola

* smoking
* past medical history of heart or lung disease
* current medical treatment for heart or lung disease
* otitis
* bad tolerance to the altitude chamber (15,000 ft): ear pain, claustrophobia

Minimum Eligible Age

25 Years

Maximum Eligible Age

45 Years

Eligible Sex

MALE

Accepts Healthy Volunteers

Yes