Studying Physiological and Anatomical Cerebral Effects of Carbon Dioxide and Tilt (SPACE-COT)

January 12, 2016 updated by: Eric Michael Bershad, Baylor College of Medicine
The purpose of this study is to study the effects of carbon dioxide combined with head down tilt on cerebral physiology and anatomy. This paradigm will help establish a ground-based analog for spaceflight, and also evaluate the ability of non-invasive devices to monitor brain physiology.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Many of the long duration astronauts develop visual changes, associated with neuroophthalmological abnormalities suggesting elevated intracranial pressure. There is currently no suitable ground based analog to simulate these changes on Earth, or a standard methodological approach to monitoring the combined effects of head down tilt and atmospheric carbon dioxide. Given that carbon dioxide and cephalad fluid shifting are known factors in spaceflight, we sought to evaluate an approach to monitoring these effects in healthy subject in a ground based analog on Earth.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
6

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

30 years to 55 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

Inclusion Criteria:

  • Male
  • Ages between 30 to 55 years old
  • Body Mass Index (BMI) of 20-26 kg/m2
  • Weight between 65-85 kg
  • Height between 158-190 cm
  • Non-smoker, for at least six months before the start of the study
  • VO2 max of at least 30ml/kg/min

Exclusion Criteria:

  • History of intracranial pressure elevation
  • History of abnormal intraocular pressure
  • Ophthalmological conditions: glaucoma, retinopathy, severe cataracts, eye trauma or implants.
  • History of diseases of the optic nerve
  • Pre-existing corneal injury
  • History of these eye surgeries: implanted lens, corneal transplant, recent (less than 6 months) LASIK surgery
  • Congenital abnormalities of the anterior chamber
  • Active eye infections, recent corneal abrasions, inflammation
  • Intraocular pressure greater than 20 mm Hg
  • Viral or bacterial eye infection Severe dry eye syndrome
  • Retinal or choroidal detachment
  • More than -6,0 dpr (high myopia)
  • More than +5,0 dpr
  • Arm or shoulder injury in the past year
  • Psychiatric conditions including major depression, bipolar disorder or severe anxiety
  • History of cerebrovascular disease including brain aneurysms, stroke, transient ischemic attack, brain hemorrhage, arteriovenous malformations History of brain tumor, congenital cysts, hydrocephalus, brain injury (requiring hospitalization)
  • Meningitis/encephalitis
  • Epilepsy
  • History of severe hypertension (> 160/90 mmHg),
  • Diabetes mellitus
  • Coronary artery disease
  • Congestive heart failure
  • Ventricular or atrial arrhythmias
  • Autonomic disorders (syncope, autoimmune neuropathy)
  • Hepatic disease
  • Renal disease
  • Chronic infections including HIV, Hepatitis B or C, Lyme disease
  • History of hematological disease including hemophilia, leukemia, thrombocytosis, thrombocytopenia, myelodysplastic syndrome, autoimmune disease (lupus, rheumatoid arthritis, Sjogren's syndrome)
  • History of malignancy except for basal cell carcinoma
  • Chronic back pain (inability to lay in bed for long periods of time)
  • Conditions that would preclude MRI including severe claustrophobia, pace maker or other metallic implants or devices
  • Sleep disturbances including: obstructive sleep apnea, narcolepsy, insomnia - Medications that exert cardiovascular, cerebrovascular or psychiatric function (i.e. beta blockers, calcium channel blockers, diuretics, diamox, sedatives) Drug, medication or alcohol abuse (regular consumption of more than 20-30 g alcohol/day)*
  • Smoking
  • VO2 max less than 30 ml/kg/min or greater than 60 ml/kg/min
  • Vegetarian, vegan
  • Migraine
  • Previous psychiatric illness
  • Hiatus hernia
  • Gastro-esophageal reflux
  • Diabetes mellitus
  • Rheumatic illness
  • Muscle or joint disorder
  • Pronounced orthostatic intolerance (< 10 min standing)
  • Hyperlipidaemia
  • Thyroid gland disorder: deviations from normal values for TSH in plasma
  • Hyper-homocysteinaemia
  • Hyperuricaemia or hypouricaemia: deviations from normal values for uric acid in plasma.
  • Hypercalcaemia or hypocalcaemia: deviations from normal values for calcium in plasma.
  • Iron deficiency
  • Vitamin D deficiency
  • Baseline blood gas values deviating from the normal reference values
  • Elevated risk of venous thromboembolism including deep venous thrombosis, pulmonary embolism
  • Chronic back complaints
  • Participation in another clinical study within the last 3 months before start of this study
  • Criminal record
  • Stomach sleepers
  • Any other medical condition that the investigators consider a contraindication to the study procedures that would make it unsafe or confound the measurements.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Atmosphere 1 - Ambient air
First, the subjects will have 1 baseline day in the upright body position. This will be followed by 28 hours of head down tilt body position and ambient air at sea level, followed by 2 hour exposure of 3% carbon dioxide inhalation.
Other: ambient air
The subjects will be randomized to breath ambient air during one of the -12 degree head down tilt body position periods in crossover design
Experimental: Atmosphere 2 - 0.5% CO2
First, the subjects will have 1 baseline day in the upright body position. This will be followed by 28 hours of head down tilt body position and air with 0.5% carbon dioxide, followed by 2 hour exposure of 3% carbon dioxide inhalation.
Other: 0.5% CO2
The subjects will be randomized to breath 0.5% carbon dioxide during one of the -12 degree head down tilt body position periods in crossover design

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Changes in cerebral blood flow: Transcranial doppler
Time Frame: 24 and 48 hours from baseline measurements
Transcranial Doppler derived measurements of mean cerebral blood flow velocity
24 and 48 hours from baseline measurements
Changes in intracranial volume
Time Frame: 24 and 48 hours from baseline measurements
Cerebrotech monitor derived intracranial fluid volume changes (percentage change)
24 and 48 hours from baseline measurements
Changes in intracranial pressure
Time Frame: 24 and 48 hours from baseline measurements
Vittamed ICP meter derived intracranial pressure (mmHg)
24 and 48 hours from baseline measurements
Changes in cognitive function
Time Frame: 24 and 48 hours from baseline measurements
Cognition battery score (max 1000): tests multiple cognitive domains including spatial memory, psychomotor processing speed, facial emotional recognition
24 and 48 hours from baseline measurements
Changes in cerebral blood flow: cFLOW
Time Frame: 24 and 48 hours from baseline measurements
cFLOW derived changes in cerebral blood flow index
24 and 48 hours from baseline measurements

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Tolerability of combined -12 head down tilt and 0.5% carbon dioxide
Time Frame: Within 48 hours from baseline
Assess safety outcomes: tolerance of condition through duration of study and number of adverse events
Within 48 hours from baseline
Changes in intraocular pressure
Time Frame: 24 and 48 hours from baseline measurements
iCare derived intraocular pressure measurements from both eyes (mmHg)
24 and 48 hours from baseline measurements
Changes in pulmonary mechanics
Time Frame: 24 and 48 hours from baseline measurements
minute ventilation, respiratory rate and vital capacity
24 and 48 hours from baseline measurements
Changes in internal jugular vein volumes
Time Frame: 48 hours from baseline measurements
Ultrasound derived measure of right internal jugular vein cross sectional areas
48 hours from baseline measurements
Changes in peripheral arterial vasoreactivity
Time Frame: 48 hours from baseline measurements
Ultrasound Doppler Measurement of arterial diameter and flow (cm/sec) after transient cuff occlusion of brachial artery
48 hours from baseline measurements
Changes in cardiac hemodynamics
Time Frame: 48 hours from baseline measurements
Assessment of cardiac output, stroke volume, heart rate, blood pressure
48 hours from baseline measurements
Changes in olfactory threshold
Time Frame: 24 and 48 hours from baseline measurement
Sniffin' sticks threshold testing for phenyethyl alcohol
24 and 48 hours from baseline measurement
Changes in pulmonary gas exchange
Time Frame: 24 and 48 hours from baseline measurements
changes in arterial pH and partial pressure CO2
24 and 48 hours from baseline measurements

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Baylor College of Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
The University of Texas Health Science Center, Houston
University of Pennsylvania
DLR German Aerospace Center
University of Cologne
Harvard University
National Space Biomedical Research Institute

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2015

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 1, 2015

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 1, 2015

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 27, 2015

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 7, 2015

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 10, 2015

Study Record Updates

Last Update Posted (Estimate)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 13, 2016

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 12, 2016

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2016

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H-36485

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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