Try our beta test site
IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more...

Cardiac Autonomic Functions During Head-out Immersion and During Head Down Tilt (IMMERSION)

This study has been completed.
Ministry of Health, France
Information provided by:
Centre Hospitalier Universitaire de Saint Etienne Identifier:
First received: August 13, 2007
Last updated: July 18, 2011
Last verified: July 2011

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°.

Condition Intervention
Other: Head-down tilt and immersion

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
Official Title: Cardiac Autonomic Functions During Head-out Immersion and During Head Down Tilt

Further study details as provided by Centre Hospitalier Universitaire de Saint Etienne:

Primary Outcome Measures:
  • heart rate variability [ Time Frame: inclusion, one week, two weeks ]

Secondary Outcome Measures:
  • Blood pressure variability [ Time Frame: inclusion, one week, two weeks ]
  • Spontaneous baroreflex activity [ Time Frame: inclusion, one week, two weeks ]
  • Pulmonary diffusion [ Time Frame: inclusion, one week, two weeks ]
  • Upper limbs vascular resistance [ Time Frame: inclusion, one week, two weeks ]
  • post ischemic forearm hyperemia [ Time Frame: inclusion, one week, two weeks ]
  • Hematocrit rate [ Time Frame: Inclusion, one week, two weeks ]
  • Cardiac haemodynamic [ Time Frame: Inclusion, one week, two weeks ]

Enrollment: 15
Study Start Date: April 2008
Study Completion Date: July 2011
Primary Completion Date: July 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1 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


Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Sportsman
  • None coffee, alcohol, cigarettes 6 hours before the start of each visit
  • Each meal must have been taken 4 hours before each visit
  • No intensive sport 48 hours before ech visit
  • Written inform consent

Exclusion Criteria:

  • Subject with cardiovascular,renal disease or with metabolic syndrome
  • Subject with medication
  • Subject who participated to an other medical research
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00515645

Centre Hospitalier de Saint-Etienne
Saint-Etienne, France, 42055
Sponsors and Collaborators
Centre Hospitalier Universitaire de Saint Etienne
Ministry of Health, France
Principal Investigator: Frédéric Roche, MD PhD Centre Hospitalier de Saint-Etienne
  More Information

Responsible Party: Clément CAILLAUX, Centre Hospitalier Universitaire de Saint Etienne Identifier: NCT00515645     History of Changes
Other Study ID Numbers: 0708061
2007-A00727-46 ( Other Identifier: AFSSAPS )
Study First Received: August 13, 2007
Last Updated: July 18, 2011

Keywords provided by Centre Hospitalier Universitaire de Saint Etienne:
Autonomic nervous system
Heart rate variability
Head-down tilt
Healthy volunteers processed this record on May 25, 2017