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

Sponsor

Direction Centrale du Service de Santé des Armées (Other)

Overall Status

Unknown status

CT.gov ID

NCT03311347

Collaborator

Uppsala University Hospital (Other), Percy Hospital (Other)

Enrollment

Locations

Arms

51.6

Anticipated Duration (Months)

Patients Per Site

0.8

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

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.

Condition or Disease	Intervention/Treatment	Phase
Pulmonary Atelectasis	Other: +Gz accelerations and positive pressure breathing	N/A

Detailed Description

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.

Study Design

Study Type:

Interventional

Anticipated Enrollment :

80 participants

Allocation:

Non-Randomized

Intervention Model:

Parallel Assignment

Intervention Model Description:

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.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.

Masking:

None (Open Label)

Primary Purpose:

Basic Science

Official Title:

Influence of Hyperoxia and Hypobaria on Atelectasis Occurrence and Mitigation of Atelectasis Formation

Actual Study Start Date :

Sep 14, 2015

Anticipated Primary Completion Date :

Jun 30, 2019

Anticipated Study Completion Date :

Jan 1, 2020

Arms and Interventions

Arm	Intervention/Treatment
Experimental: 100%O2 breathing Primary aim, item 1	Other: +Gz accelerations and positive pressure breathing
Experimental: Air breathing Primary aim, item 1	Other: +Gz accelerations and positive pressure breathing

Arm

Intervention/Treatment

Experimental: 100%O2 breathing

Primary aim, item 1

Other: +Gz accelerations and positive pressure breathing

Experimental: Air breathing

Primary aim, item 1

Other: +Gz accelerations and positive pressure breathing

Outcome Measures

Primary Outcome Measures

atelectasis formation (change between pre and post-protocol) [pre-protocol (baseline) and 1h30 min after centrifuge stop]
computerized tomography: 0-5 scale for size and localization
change in pulmonary ventilation between 1 Gz, 1.6 Gz and 3.5 Gz [pre-protocol (baseline), baseline + 1hr, baseline +1h10 min, baseline +1h15 min]
electrical impedance tomography: deltaZ on regions of interest
change in pulmonary tissue density from baseline at centrifuge stop and 1h30 min after stop [pre protocol (baseline), at centrifuge stop (baseline + 1h15 min) and 1h30 min after centrifuge stop]
ultrasound: number of lung comets + localization

Eligibility Criteria

Criteria

Ages Eligible for Study:

25 Years to 45 Years

Sexes Eligible for Study:

Male

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

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

Aim 1 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