Intravascular Volumes in Hypoxia During Antarctic Confinement

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

24 participants

Study Classification

INTERVENTIONAL

Study Start Date

2019-09-27

Study Completion Date

2022-12-31

Brief Summary

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This study evaluates the effect of hypoxia on blood volumes during Antarctic winter-over confinement. Half of the participants will be evaluated during sea-level winter-over confinement, while the other half will be examined during high-altitude hypoxia winter-over confinement.

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Detailed Description

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INTRODUCTION: Short-term space flight induces an alteration of circulating blood volumes, termed "space flight anemia" and characterized by a decrease in total red blood cell volume (RCV) and plasma volume (PV). This haematological alteration is likely to persist during a long-term space mission and impact the astronauts' health, however this question remains unexplored. During a long-term space mission, the use of hypobaric hypoxia is considered for technical reasons, however the safety of hypoxia must first be verified because this environmental condition causes substantial physiological changes, in particular changes in blood volumes that may interact with the haematological effects of microgravity.

OBJECTIVE: using the Antarctic confinement model as a high-fidelity terrestrial analogue for long-duration space missions, the investigators hypothesize that 1) sea level confinement reduces blood volume by simultaneously decreasing RCV and PV, and 2) chronic hypoxia offsets the decrease in RCV and exacerbates the decrease in PV induced by confinement.

METHODS: blood volumes will be measured via the carbon-monoxide rebreathing method, repeatedly in two groups of participants, overwintering either at Dumont d'Urville (sea level) or Concordia (altitude 3200 m). The blood viscosity will also be measured, as well as the markers of erythropoiesis and iron metabolism.

PERSPECTIVE: Documenting if some degree of hypoxia during long-duration confinement may be beneficial or unfavorable in terms of blood volume regulation is potentially relevant information for the astronauts' health and safety during long-duration space missions.

Conditions

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Hypoxia Confinement

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

one group wintering at sea level and one group wintering at high altitude

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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hypoxia & confinement

Participants exposed to high-altitude hypoxia and confinement during a one-year stay at Concordia station, Antarctica (3200 m)

Group Type EXPERIMENTAL

carbon-monoxide rebreathing

Intervention Type OTHER

Inhaled carbon monoxide (CO) administrated as a bolus into a rebreathing circuit serves as a marker to tag circulating hemoglobin molecules and to calculate total hemoglobin mass (Hbmass). The change in blood CO concentration from pre- to postadministration (delta carboxyhemoglobin concentration) and the dose of administrated CO allows for Hbmass determination. The other blood compartments (total red blood cell volume, plasma volume and total blood volume) are derived from Hbmass, hematocrit and/or hemoglobin concentration.

venous blood sampling

Intervention Type OTHER

venous blood sampling at rest to evaluate blood viscosity, erythropoiesis and iron metabolism

physical activity monitoring

Intervention Type OTHER

recording of physical activity by actimetry

apnea-hypopnea index and nocturnal oxygenation

Intervention Type OTHER

recorded by ambulatory sleep recording device

24-hour blood pressure

Intervention Type OTHER

recorded by ambulatory device

confinement

Participants exposed to confinement during a one-year stay at Dumont d'Urville station, Antarctica (sea level)

Group Type ACTIVE_COMPARATOR

carbon-monoxide rebreathing

Intervention Type OTHER

Inhaled carbon monoxide (CO) administrated as a bolus into a rebreathing circuit serves as a marker to tag circulating hemoglobin molecules and to calculate total hemoglobin mass (Hbmass). The change in blood CO concentration from pre- to postadministration (delta carboxyhemoglobin concentration) and the dose of administrated CO allows for Hbmass determination. The other blood compartments (total red blood cell volume, plasma volume and total blood volume) are derived from Hbmass, hematocrit and/or hemoglobin concentration.

venous blood sampling

Intervention Type OTHER

venous blood sampling at rest to evaluate blood viscosity, erythropoiesis and iron metabolism

physical activity monitoring

Intervention Type OTHER

recording of physical activity by actimetry

apnea-hypopnea index and nocturnal oxygenation

Intervention Type OTHER

recorded by ambulatory sleep recording device

24-hour blood pressure

Intervention Type OTHER

recorded by ambulatory device

Interventions

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carbon-monoxide rebreathing

Inhaled carbon monoxide (CO) administrated as a bolus into a rebreathing circuit serves as a marker to tag circulating hemoglobin molecules and to calculate total hemoglobin mass (Hbmass). The change in blood CO concentration from pre- to postadministration (delta carboxyhemoglobin concentration) and the dose of administrated CO allows for Hbmass determination. The other blood compartments (total red blood cell volume, plasma volume and total blood volume) are derived from Hbmass, hematocrit and/or hemoglobin concentration.

Intervention Type OTHER

venous blood sampling

venous blood sampling at rest to evaluate blood viscosity, erythropoiesis and iron metabolism

Intervention Type OTHER

physical activity monitoring

recording of physical activity by actimetry

Intervention Type OTHER

apnea-hypopnea index and nocturnal oxygenation

recorded by ambulatory sleep recording device

Intervention Type OTHER

24-hour blood pressure

recorded by ambulatory device

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Affiliated to a social security scheme
* Ability to communicate and read in English or in French
* Signed written informed consent form after visit with a MD