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Completed

NCT Number: NCT01782625

Hypercapnia: Cognitive Effects and Monitoring

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).

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Key information

Conditions

Hypercapnia Behavior Chemically-Induced Disorders Cognition Disorders Cognitive Dysfunction Consciousness Disorders Diving Exercise Gas Poisoning Immersion Inert Gas Narcosis Mental Disorders Motor Activity Nervous System Diseases Neurobehavioral Manifestations Neurocognitive Disorders Neurologic Manifestations Nitrogen Narcosis Occupational Diseases Pathological Conditions, Signs and Symptoms Poisoning Signs and Symptoms Signs and Symptoms, Respiratory Stupor Unconsciousness

Age range

18 year–50 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Duke Center for Hyperbaric Medicine and Environmental Physiology

Durham, North Carolina, 27710, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

NO exercise at depth

Other

Subjects will NOT exercise while at depth

exercise at depth

Other

Subjects will exercise while at depth

Primary outcomes

  1. 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 outcomes

  1. 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)

Sponsors and collaborators

Lead sponsor

Duke University

Other

Registry information

Important dates

Study start
2013
Primary completion
2016
Study completion
2016
First posted
Feb 4, 2013
Registry last updated
May 25, 2016

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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