Cardiac Autonomic Functions During Head-Out Immersion and During Head Down Tilt - Full Text View

Purpose

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. Its 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 cardio-vascular 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. We suppose an increase of parasympathetic activity during WI corresponding to parasympathetic activation during HDT especially at -6°.

Condition	Intervention
Healthy	Other: Head-down tilt and immersion

U.S. FDA Resources

Study Type:	Interventional
Study Design:	Basic Science, Non-Randomized, Open Label, Uncontrolled, Single Group Assignment, Efficacy Study

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 ] [ Designated as safety issue: No ]

Secondary Outcome Measures:

Blood pressure variability [ Time Frame: inclusion, one week, two weeks ] [ Designated as safety issue: No ]
Spontaneous baroreflex activity [ Time Frame: inclusion, one week, two weeks ] [ Designated as safety issue: No ]
Pulmonary diffusion [ Time Frame: inclusion, one week, two weeks ] [ Designated as safety issue: No ]
Upper limbs vascular resistance [ Time Frame: inclusion, one week, two weeks ] [ Designated as safety issue: No ]
post ischemic forearm hyperemia [ Time Frame: inclusion, one week, two weeks ] [ Designated as safety issue: No ]
Hematocrit rate [ Time Frame: Inclusion, one week, two weeks ] [ Designated as safety issue: No ]
Cardiac haemodynamic [ Time Frame: Inclusion, one week, two weeks ] [ Designated as safety issue: No ]

Estimated Enrollment:	25
Study Start Date:	April 2008
Estimated Study Completion Date:	September 2009
Estimated Primary Completion Date:	September 2009 (Final data collection date for primary outcome measure)

Arms	Assigned Interventions
1: Experimental	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

Eligibility

Ages Eligible for Study:	18 Years to 40 Years
Genders Eligible for Study:	Male
Accepts Healthy Volunteers:	Yes

Criteria

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

Please refer to this study by its ClinicalTrials.gov identifier: NCT00515645

Contacts


Contact: Frédéric ROCHE, MD	+33 477828300	frederic.roche@univ-st-etienne.fr

Contact: Jean Claude BARTHELEMY, MD	+33 477828300	JC.Barthelemy@univ-st-etienne.fr

Locations


France
	Centre Hospitalier de Saint-Etienne	Recruiting
	Saint-Etienne, France, 42055
	Contact: Fréderic ROCHE, MD +33 477828300 frederic.roche@univ-st-etienne.fr
	Contact: Florian CHOUCHOU +33 477828300 florianchouchou@hotmail.fr
	Sub-Investigator: Jean Claude BARTHELEMY, MD
	Sub-Investigator: Frédéric COSTES, MD

Sponsors and Collaborators

Centre Hospitalier Universitaire de Saint Etienne

Investigators


Principal Investigator:	Frédéric ROCHE, MD	Centre Hospitalier de Saint-Etienne

More Information

Publications:

Gabrielsen A, Johansen LB, Norsk P. Central cardiovascular pressures during graded water immersion in humans. J Appl Physiol. 1993 Aug;75(2):581-5.

Shiraishi M, Schou M, Gybel M, Christensen NJ, Norsk P. Comparison of acute cardiovascular responses to water immersion and head-down tilt in humans. J Appl Physiol. 2002 Jan;92(1):264-8.

Ueno LM, Miyachi M, Matsui T, Takahashi K, Yamazaki K, Hayashi K, Onodera S, Moritani T. Effect of aging on carotid artery stiffness and baroreflex sensitivity during head-out water immersion in man. Braz J Med Biol Res. 2005 Apr;38(4):629-37. Epub 2005 Apr 13.

Responsible Party:	Centre Hospitalier Universitaire de Saint Etienne ( Françoise LORCA )
Study ID Numbers:	2007-A00727-46, 0708061
First Received:	August 13, 2007
Last Updated:	July 25, 2008
ClinicalTrials.gov Identifier:	NCT00515645
Health Authority:	France: Ministry of Health; France: French Data Protection Authority

Keywords provided by Centre Hospitalier Universitaire de Saint Etienne:

Autonomic nervous system

Immersion

Heart rate variability

Head-down tilt

Healthy volunteers

Study placed in the following topic categories:

Healthy

ClinicalTrials.gov processed this record on October 10, 2008

Sponsored by:	Centre Hospitalier Universitaire de Saint Etienne
Information provided by:	Centre Hospitalier Universitaire de Saint Etienne
ClinicalTrials.gov Identifier:	NCT00515645