Effect of Hyperbaric Oxygen Therapy on Microcirculation (MICROHB)

January 6, 2026 updated by: University Hospital, Lille

Effect of Hyperbaric Oxygen Therapy on Healthy Volunteers Microcirculation

Previous studies shoes that hyperoxia alters microcirculation.The investigators hypothesize that hyperbaric may restore microcirculation integrity. This hypothesis is supported by a recent study in rabbits, but no data exists for humans.

The study will expose fifteen healthy volunteers to a succession of different fraction of inspired oxygen and barometric pressure and assess microcirculatory and macrocirculatory changes via sidestream dark field videomicroscopy, near-infrared spectroscopy, Laser Doppler, transthoracic echocardiography and bio-impedancemetry at every step.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Microcirculation alterations and hyperoxia are known to alter ICU-patients' prognostic.

Studies have shown that hyperoxia alters healthy volunteers' microcirculation, whereas hyperbaric oxygen therapy is commonly used to facilitate cicatrization. There seems to be a paradox. A recent study in rabbits has given some evidences that hyperbaria may restore microcirculation integrity, but to date, there is no such evidences in human.

To study hyperoxia and hyperbaric induced changes in micro and macrocirculation, fifteen healthy volunteers will be exposed to successive variations of inspired oxygen fraction and barometric pressure according to a predefine sequence so that only one parameter will change from a condition to the next one :

  1. FiO2 0.21 - 1 ATA
  2. FiO2 1 - 1 ATA
  3. FiO2 1 - 2.5 ATA
  4. FiO2 0.21 - 2.5 ATA
  5. FiO2 0.21 - 1 ATA

At each time, and after a 30 minutes period of exposure, measures will be made using SDF-microscopy, Laser Doppler and NIRS to assess microcirculation.

As previously described, macrocirculation can modify microcirculation due to a mechanism called hemodynamic coherence.

Hence, the investigators planned to assess macrocirculation changes at every step of the protocol using bioimpedancemetry and transthoracic echocardiography.

Each volunteer will be his own control, using the first measurements (condition 1. FiO2 0.21 - 1 ATA) as reference.

Study Type

Interventional

Enrollment (Actual)

15

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • France
      • Lille, France
        • Hôpital Roger Salengro, CHU

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 64 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • To provide a medical certificate of fitness to dive (< 1 year)
  • Consent given for study participation
  • French health insurance affiliated

Exclusion Criteria:

  • Temporary or definitive contra-indication to dive
  • Pregnancy or < 18 years of age
  • Precedent dive < 24 hours
  • Under a legal protection measure
  • Medical history of a disease known to alter microcirculation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Hyperbaric oxygen therapy

Successive changes in fraction of inspired oxygen and barometric pressure (ATA: Atmosphere absolute)

Five successive steps:

  1. FiO2 0.21 - 1 ATA
  2. FiO2 1 - 1 ATA
  3. FiO2 1 - 2.5 ATA
  4. FiO2 0.21 - 2.5 ATA
  5. FiO2 0.21 - 1 ATA
Procedure: Hyperbaric oxygen therapy
  1. FiO2 0.21 - 1 ATA
  2. FiO2 1 - 1 ATA
  3. FiO2 1 - 2.5 ATA
  4. FiO2 0.21 - 2.5 ATA
  5. FiO2 0.21 - 1 ATA

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in proportion of perfused vessel (PPV)
Time Frame: 30 minutes after hyperbaric hyperoxia exposure (FiO2 1 - 2.5 ATA)
Proportion of perfused vessel assessed by Sidestream dark field microscopy on the sublingual mucosa
30 minutes after hyperbaric hyperoxia exposure (FiO2 1 - 2.5 ATA)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in proportion of perfused vessel (PPV)
Time Frame: 30 minutes after FiO2 1 - 1 ATA exposure
Proportion of perfused vessel assessed by Sidestream dark field microscopy on the sublingual mucosa
30 minutes after FiO2 1 - 1 ATA exposure
Changes in proportion of perfused vessel (PPV)
Time Frame: 30 minutes after FiO2 0.21 - 2.5 ATA exposure
Proportion of perfused vessel assessed by Sidestream dark field microscopy on the sublingual mucosa
30 minutes after FiO2 0.21 - 2.5 ATA exposure
Changes in hyperemic reaction after a vaso-occlusion test
Time Frame: 30 minutes after FiO2 1 - 2.5 ATA exposure
Area under curve assessed by near-infrared spectroscopy
30 minutes after FiO2 1 - 2.5 ATA exposure
Changes in area of hyperaemia after a vaso-occlusion test
Time Frame: 30 minutes after FiO2 1 - 2.5 ATA exposure
Area under curve assessed by Laser-Doppler
30 minutes after FiO2 1 - 2.5 ATA exposure
Validation of cardiac output assessed by bioimpedancemetry under hyperbaric condition
Time Frame: 30 minutes after FiO2 1 - 2.5 ATA exposure
Comparison with transthoracic echocardiography
30 minutes after FiO2 1 - 2.5 ATA exposure

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University Hospital, Lille

Investigators

  • Principal Investigator: Thibault Duburcq, MD, University Hospital, Lille

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 14, 2019

Primary Completion (Actual)

July 25, 2019

Study Completion (Actual)

July 25, 2019

Study Registration Dates

First Submitted

May 15, 2019

First Submitted That Met QC Criteria

June 5, 2019

First Posted (Actual)

June 10, 2019

Study Record Updates

Last Update Posted (Estimated)

January 8, 2026

Last Update Submitted That Met QC Criteria

January 6, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2018_63
  • 2019-A00053-54 (Registry Identifier: ID-RCB - ANSM)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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