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Cardiac Autonomic Functions During Head-out Immersion and During Head Down Tilt

NCT00515645 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 15

Last updated 2020-05-11

No results posted yet for this study

Summary

Head down tilt (HDT) was widely used to simulate microgravity effects on cardiovascular system. HDT could be a suitable model of water immersion (WI) which is also used to simulate the cardiovascular effects of microgravity and which is not easy to study in laboratory. To define the possibility to simulate immersion by HDT, a comparison between these models is required. A comparison between WI and few angles during HDT seems necessary to understand which angle is more adapt.

The immersion induces an increase of the central blood volume. This increase is caused by a redistribution of blood from peripheral portions of the body to the intrathoracic circulation. It seems to load cardiopulmonary and arterial baroreceptors. These baroreceptors bring into play autonomic nervous system (ANS) activation and induce a bradycardia.

HDT induces an increase in central blood volume as supported by the central venous pressure and cardiac volume increase and in return, MSNA and heart rate decrease. These cardiovascular effects seem to be the same as the thermoneutral immersion and suggest that the ANS activation is the same during HDT and WI.

Nevertheless, a few previous studies about ANS in HDT indicate some discordant results: a sympathetic decrease was reported but several results show an increase of parasympathetic activity linked with a trend of increase of arterial baroreflex. The aim of this study is to assess ANS activity in HDT on different angles (-6° and -15°) and WI. The investigators suppose an increase of parasympathetic activity during WI corresponding to parasympathetic activation during HDT especially at -6°.

Conditions

  • Healthy

Interventions

OTHER

Head-down tilt and immersion

Head-down tilt -6° at inclusion, head-down tilt -15° at week one and Water Immersion at week two

Sponsors & Collaborators

  • Ministry of Health, France

    collaborator OTHER_GOV

  • Centre Hospitalier Universitaire de Saint Etienne

    lead OTHER

Principal Investigators

  • Frédéric Roche, MD PhD · Centre Hospitalier de Saint-Etienne

Study Design

Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Model
SINGLE_GROUP

Eligibility

Min Age
18 Years
Max Age
40 Years
Sex
MALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2008-04-30
Primary Completion
2011-07-31
Completion
2011-07-31

Countries

  • France

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00515645 on ClinicalTrials.gov