Title
Inspired Carbon Dioxide During Hypoxia: Effects on Task Performance and Cerebral Oxygen Saturation
Author
van Dorp, E.
Los, M.
Dirven, P.
Sarton, E.
Valk, P.
Teppema, L.
Stienstra, R.
Dahan, A.
TNO Defensie en Veiligheid
Publication year
2007
Abstract
Introduction: Exposure to a hypoxic environment has a deleterious effect on physiological and mental functions. We studied the effect of added inspired CO2 during artificially induced hypoxic normobaric hypoxia (oxygen saturation ∼80%) on complex task performance. Methods: In random order, 22 healthy volunteers were exposed to 3 gas mixtures for 50 min each: sham hypoxia (SH, PetO2 103 mmHg without inspired CO2); isocapnic hypoxia (IH, PetO2 ∼40 mmHg, PetCO2 clamped to 0.4 mmHg above resting values); and poikilocapnic hypoxia (PH, PetO2 ∼40 mmHg; no inspired CO2). Brain oxygenation was measured using near infrared spectroscopy. During minutes 25-45 of hypoxia, subjects performed vigilance and task performance tests used in aviation research: the Vigilance and Tracking test and the Multi-Attribute Task battery (MAT-bat). The tests varied in difficulty with the tracking tests considered most difficult. Results: PetCO2 levels differed significantly among groups: IH 42.8 ± 0.7, SH 39.0 ± 0.7, and PH 36.8 ± 0.7 mmHg. Brain oxygenation levels were significantly higher during IH than PH (62.2 ± 1.0 vs. 59.1 ± 1.3%). The results of the performance tests indicated a negative effect of PH vs. SH on most function tests. For the Tracking test of the MAT-bat, performance was worst during PH, but returned to baseline during IH. Discussion: We demonstrate the ability of added inspired CO2 to improve performance during hypoxia by preventing PH-associated hypocapnia-induced vasoconstriction of brain blood vessels. Our results are relevant to aerospace medicine and other circumstances in which complex tasks are performed in a hypoxic environment such as mountain climbing and working in confined spaces. Copyright © by Aerospace Medical Association.
Subject
Aviation
Complex task performance
Isocapnia
Poikilocapnia
Simulation of piloting
Vigilance
Carbon dioxide
Alertness
Infrared spectroscopy
Multi attribute task battery
Oxygen saturation
Task performance
Vasoconstriction
Vigilance and tracking test
Carbon Dioxide
Cerebrovascular Circulation
Cognition
Brain
Oximetry
Oxygen
Pulmonary Ventilation
Spectroscopy, Near-Infrared
Task Performance and Analysis
Tidal Volume
To reference this document use:
http://resolver.tudelft.nl/uuid:0653c477-4108-4924-ba31-fadde02761c0
TNO identifier
20074
Source
Aviation, Space, and Environmental Medicine, 78 (7), 666-672
Document type
article