NCT00515645

Brief 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°.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
15

participants targeted

Target at below P25 for not_applicable healthy

Timeline
Completed

Started Apr 2008

Longer than P75 for not_applicable healthy

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

August 13, 2007

Completed
1 day until next milestone

First Posted

Study publicly available on registry

August 14, 2007

Completed
8 months until next milestone

Study Start

First participant enrolled

April 1, 2008

Completed
3.2 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

July 1, 2011

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

July 1, 2011

Completed
Last Updated

May 11, 2020

Status Verified

May 1, 2020

Enrollment Period

3.2 years

First QC Date

August 13, 2007

Last Update Submit

May 7, 2020

Conditions

Healthy

Keywords

Autonomic nervous systemImmersionHeart rate variabilityHead-down tiltHealthy volunteers

Outcome Measures

Primary Outcomes (1)

  • heart rate variability

    inclusion, one week, two weeks

Secondary Outcomes (7)

  • Blood pressure variability

    inclusion, one week, two weeks

  • Spontaneous baroreflex activity

    inclusion, one week, two weeks

  • Pulmonary diffusion

    inclusion, one week, two weeks

  • Upper limbs vascular resistance

    inclusion, one week, two weeks

  • post ischemic forearm hyperemia

    inclusion, one week, two weeks

  • +2 more secondary outcomes

Study Arms (1)

1

EXPERIMENTAL
Other: Head-down tilt and immersion

Interventions

Head-down tilt and immersionOTHER

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

1

Eligibility Criteria

Age18 Years - 40 Years
Sexmale
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • 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

You may not qualify if:

  • Subject with cardiovascular,renal disease or with metabolic syndrome
  • Subject with medication
  • Subject who participated to an other medical research

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Centre Hospitalier de Saint-Etienne

Saint-Etienne, 42055, France

Location

Related Publications (3)

  • Gabrielsen A, Johansen LB, Norsk P. Central cardiovascular pressures during graded water immersion in humans. J Appl Physiol (1985). 1993 Aug;75(2):581-5. doi: 10.1152/jappl.1993.75.2.581.

    PMID: 8226455BACKGROUND

  • 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 (1985). 2002 Jan;92(1):264-8. doi: 10.1152/jappl.2002.92.1.264.

    PMID: 11744669BACKGROUND

  • 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. doi: 10.1590/s0100-879x2005000400018. Epub 2005 Apr 13.

    PMID: 15962190BACKGROUND

MeSH Terms

Interventions

Head-Down TiltImmersion

Intervention Hierarchy (Ancestors)

PostureMusculoskeletal Physiological PhenomenaMusculoskeletal and Neural Physiological PhenomenaInvestigative Techniques

Study Officials

  • Frédéric Roche, MD PhD

    Centre Hospitalier de Saint-Etienne

    PRINCIPAL INVESTIGATOR

Study Design

Study Type
interventional
Phase
not applicable
Allocation
NA
Masking
NONE
Purpose
BASIC SCIENCE
Intervention Model
SINGLE GROUP
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

August 13, 2007

First Posted

August 14, 2007

Study Start

April 1, 2008

Primary Completion

July 1, 2011

Study Completion

July 1, 2011

Last Updated

May 11, 2020

Record last verified: 2020-05

Locations

FR(1)