Hyperbaric Oxygen Therapy
Conditions
Keywords
Hyperbaric oxygen therapy, Normobaric oxygen therapy, Hyperoxia, Sidestream dark field videomicroscopy, Microcirculation
Brief summary
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.
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.
Interventions
PROCEDUREHyperbaric 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
Sponsors
University Hospital, Lille
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 64 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Changes in proportion of perfused vessel (PPV) | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Changes in proportion of perfused vessel (PPV) | 30 minutes after FiO2 1 - 1 ATA exposure | Proportion of perfused vessel assessed by Sidestream dark field microscopy on the sublingual mucosa |
| Changes in hyperemic reaction after a vaso-occlusion test | 30 minutes after FiO2 1 - 2.5 ATA exposure | Area under curve assessed by near-infrared spectroscopy |
| Changes in area of hyperaemia after a vaso-occlusion test | 30 minutes after FiO2 1 - 2.5 ATA exposure | Area under curve assessed by Laser-Doppler |
| Validation of cardiac output assessed by bioimpedancemetry under hyperbaric condition | 30 minutes after FiO2 1 - 2.5 ATA exposure | Comparison with transthoracic echocardiography |
Countries
France
Outcome results
None listed