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Hypercapnia: Cognitive Effects and Monitoring

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT01782625
First Posted: February 4, 2013
Last Update Posted: May 25, 2016
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by (Responsible Party):
Duke University
  Purpose

The investigators will simulate the conditions of a working, helmeted diver by using exercising, "head out" immersed subjects to test the following hypotheses:

  1. An algorithm can be developed which predicts cognitive performance in immersed exercising divers, based on the exhaled carbon dioxide (PETCO2) and the diver's inspired partial pressures of oxygen and nitrogen (PIO2 and PIN2).
  2. PETCO2 using mass spectrometry is an accurate estimate of arterial carbon dioxide (PaCO2) at rest and during immersed exercise and can be used as a PaCO2 surrogate at levels exceeding 50 mmHg and depths up to 158 fsw (gas density 6.4 g/l, similar to 165 fsw density of 6.8 g/l).

Condition Intervention
Hypercapnia Exercise Nitrogen Narcosis Diving Immersion Other: NO exercise at depth Other: exercise at depth

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Hypercapnia: Cognitive Effects and Monitoring

Resource links provided by NLM:


Further study details as provided by Duke University:

Primary Outcome Measures:
  • Is cognitive ability different while resting versus compared to cognitive ability while diving, breathing different gas mixtures and while exercising? [ Time Frame: pre-dive to dive to post-dive (approximately 2 hours) ]
    Subjects will undergo computerized cognitive testing before, during and after a simulated dive in the Duke Hyperbaric Chamber. Different exercise conditions (rest or exercise) and different breathing gas mixtures (added carbon dioxide or not)will be assessed and compared to the pre-dive conditions.


Secondary Outcome Measures:
  • How does exhaled (end tidal) carbon dioxide compare with arterial carbon dioxide? [ Time Frame: pre-dive to dive to post dive (approximately 2 hours) ]
    Exhaled (end tidal) carbon dioxide will be compared to arterial carbon dioxide at the various experimental conditions of the study (at the surface versus during the dive, during exercise versus during rest, breathing gas with added carbon dioxide versus breathing gas without added carbon dioxide)


Enrollment: 58
Study Start Date: January 2013
Study Completion Date: February 2016
Primary Completion Date: February 2016 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: dive to 122 feet, no exercise
Subjects will undergo a simulated dive to a maximum depth of 122 feet of seawater with no exercise at depth
Other: NO exercise at depth
Subjects will NOT exercise while at depth
Experimental: dive to 158 feet, no exercise
Subjects will undergo a simulated dive to a maximum depth of 154 feet of seawater with no exercise at depth
Other: NO exercise at depth
Subjects will NOT exercise while at depth
Experimental: dive to 122 feet, exercise
Subjects will undergo a simulated dive to a maximum depth of 122 feet of seawater with exercise at depth
Other: exercise at depth
Subjects will exercise while at depth
Experimental: dive to 158 feet, exercise
Subjects will undergo a simulated dive to a maximum depth of 154 feet of seawater with exercise at depth.
Other: exercise at depth
Subjects will exercise while at depth

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 50 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • healthy,
  • male,
  • age greater than 18,
  • age less than 50

Exclusion Criteria:

  • smoker,
  • asthma,
  • cardiac disease,
  • inability to pedal a bicycle ergometer,
  • inability to perform vigorous exercise
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01782625


Locations
United States, North Carolina
Duke Center for Hyperbaric Medicine and Environmental Physiology
Durham, North Carolina, United States, 27710
Sponsors and Collaborators
Duke University
Investigators
Principal Investigator: John J Freiberger, MD Duke University
  More Information

Responsible Party: Duke University
ClinicalTrials.gov Identifier: NCT01782625     History of Changes
Other Study ID Numbers: Pro00036937
SPS 181258 ( Registry Identifier: Sponsored Programs )
First Submitted: January 31, 2013
First Posted: February 4, 2013
Last Update Posted: May 25, 2016
Last Verified: May 2016

Keywords provided by Duke University:
diving
cognitive impairment
nitrogen narcosis
narcosis
end tidal carbon dioxide
arterial carbon dioxide
immersion

Additional relevant MeSH terms:
Hypercapnia
Stupor
Inert Gas Narcosis
Signs and Symptoms, Respiratory
Signs and Symptoms
Unconsciousness
Consciousness Disorders
Neurobehavioral Manifestations
Neurologic Manifestations
Nervous System Diseases
Occupational Diseases
Gas Poisoning
Poisoning
Chemically-Induced Disorders