Diving, Exercise, Hypercapnia, Immersion, Nitrogen Narcosis
Conditions
Keywords
diving, cognitive impairment, nitrogen narcosis, narcosis, end tidal carbon dioxide, arterial carbon dioxide, immersion
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).
Interventions
OTHERNO exercise at depth
Subjects will NOT exercise while at depth
OTHERexercise at depth
Subjects will exercise while at depth
Sponsors
Duke University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
MALE
Age
18 Years to 50 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Is cognitive ability different while resting versus compared to cognitive ability while diving, breathing different gas mixtures and while exercising? | 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
| Measure | Time frame | Description |
|---|---|---|
| How does exhaled (end tidal) carbon dioxide compare with arterial carbon dioxide? | 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) |
Countries
United States
Outcome results
None listed