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

Pulmonary Atelectasis Clinical Trial

Official title:

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

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT03311347
• Other study ID #: PDH1-SMO2-0714
• Status: Recruiting
• Phase: N/A
• Start date: September 14, 2015
• Est. completion date: January 1, 2020

Study information

• Verified date: May 2019
• Source: Direction Centrale du Service de Santé des Armées
• Contact: Stephanie S Montmerle-Borgdorff, MD, PhD
• Phone: +33(1)78651249
• Email: stephanie.montmerle[@]intradef.gouv.fr
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 80
• Est. completion date: January 1, 2020
• Est. primary completion date: June 30, 2019
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 25 Years to 45 Years

Eligibility

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

Aim 2 exclusion criteria:

• 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

Related Conditions & MeSH terms

• Hyperoxia
• Pulmonary Atelectasis

Intervention

Other:
• +Gz accelerations and positive pressure breathing

Locations

Country	Name	City	State
France	Armed Forces Biomedical Research Institute	Brétigny-sur-Orge
France	Department of Radiology, Percy hospital	Clamart

Sponsors (3)

Lead Sponsor	Collaborator
Direction Centrale du Service de Santé des Armées	Percy Hospital, Uppsala University Hospital

Country where clinical trial is conducted

France, 

References & Publications (2)

Borges JB, Hedenstierna G, Bergman JS, Amato MB, Avenel J, Montmerle-Borgdorff S. First-time imaging of effects of inspired oxygen concentration on regional lung volumes and breathing pattern during hypergravity. Eur J Appl Physiol. 2015 Feb;115(2):353-63 — View Citation

Dussault C, Gontier E, Verret C, Soret M, Boussuges A, Hedenstierna G, Montmerle-Borgdorff S. Hyperoxia and hypergravity are independent risk factors of atelectasis in healthy sitting humans: a pulmonary ultrasound and SPECT/CT study. J Appl Physiol (1985). 2016 Jul 1;121(1):66-77. doi: 10.1152/japplphysiol.00085.2016. Epub 2016 Apr 21. — View Citation

Outcome

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