Clinical Trial: Hypercapnia: Cognitive Effects and Monitoring

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Hypercapnia: Cognitive Effects and Monitoring

Brief Summary:

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).

Detailed Summary:
Sponsor: Duke University

Current Primary Outcome: 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.


Original Primary Outcome: Same as current

Current Secondary Outcome: 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)


Original Secondary Outcome: Same as current

Information By: Duke University

Dates:
Date Received: January 31, 2013
Date Started: January 2013
Date Completion:
Last Updated: May 24, 2016
Last Verified: May 2016