Hypercapnia: Cognitive Effects and Monitoring

Duke University

Status: Completed

Conditions: Hypercapnia; Nitrogen Narcosis; Immersion; Diving; Exercise

Treatments: Other: NO exercise at depth; Other: exercise at depth

Study type: Interventional

Funder types: Other

Identifiers

NCT01782625

SPS 181258 (Registry Identifier)

Pro00036937

Details and patient eligibility

About

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).

Enrollment: 58 patients

Sex: Male

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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58 participants in 4 patient groups

dive to 122 feet, no exercise

Experimental group

Description:

Subjects will undergo a simulated dive to a maximum depth of 122 feet of seawater with no exercise at depth

Treatment:

Other: NO exercise at depth

dive to 158 feet, no exercise

Experimental group

Description:

Subjects will undergo a simulated dive to a maximum depth of 154 feet of seawater with no exercise at depth

Treatment:

Other: NO exercise at depth

dive to 122 feet, exercise

Experimental group

Description:

Subjects will undergo a simulated dive to a maximum depth of 122 feet of seawater with exercise at depth

Treatment:

Other: exercise at depth

dive to 158 feet, exercise

Experimental group

Description:

Subjects will undergo a simulated dive to a maximum depth of 154 feet of seawater with exercise at depth.

Treatment:

Other: exercise at depth