title: Assessment of the interaction of hyperbaric N2, CO2, and O2 on psychomotor performance in divers.
abstract: Diving narcosis results from the complex interaction of gases, activities, and environmental conditions. We hypothesized that these interactions could be separated into their component parts. Where previous studies have tested single cognitive tasks sequentially, we varied inspired partial pressures of CO2, N2, and O2in immersed, exercising subjects while assessing multitasking performance with the Multi-Attribute Task Battery II (MATB-II) flight simulator. Cognitive performance was tested under 20 conditions of gas partial pressure and exercise in 42 male subjects meeting U.S. Navy age and fitness profiles. Inspired nitrogen (N2) and oxygen (O2) partial pressures were 0, 4.5, and 5.6 ATA and 0.21, 1.0, and 1.22 ATA, respectively, at rest and during 100-W immersed exercise with and without 0.075-ATA CO2Linear regression modeled the association of gas partial pressure with task performance while controlling for exercise, hypercapnic ventilatory response, dive training, video game frequency, and age. Subjects served as their own controls. Impairment of memory, attention, and planning, but not motor tasks, was associated with N2partial pressures >4.5 ATA. Sea level O2at 0.925 ATA partially rescued motor and memory reaction time impaired by 0.075-ATA CO2; however, at hyperbaric pressures an unexpectedly strong interaction between CO2, N2, and exercise caused incapacitating narcosis with amnesia, which was augmented by O2Perception of narcosis was not correlated with actual scores. The relative contributions of factors associated with diving narcosis will be useful to predict the effects of gas mixtures and exercise conditions on the cognitive performance of divers. The O2effects are consistent with O2narcosis or enhanced O2toxicity.
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina john.freiberger@duke.edu.
authors.forename: J J
authors.identifier: 0000-0002-1871-9430
authors.initials: JJ
authors.lastname: Freiberger
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: B J
authors.initials: BJ
authors.lastname: Derrick
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: M J
authors.initials: MJ
authors.lastname: Natoli
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: I
authors.initials: I
authors.lastname: Akushevich
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: E A
authors.initials: EA
authors.lastname: Schinazi
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: C
authors.initials: C
authors.lastname: Parker
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: B W
authors.initials: BW
authors.lastname: Stolp
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: P B
authors.initials: PB
authors.lastname: Bennett
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: R D
authors.initials: RD
authors.lastname: Vann
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: S A S
authors.initials: SA
authors.lastname: Dunworth
authors.affiliation: Duke Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: R E
authors.initials: RE
authors.lastname: Moon
mesh_terms: D000328:Adult; D001274:Atmospheric Pressure; D002245:Carbon Dioxide / Q000097:blood*; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology; D004242:Diving / Q000009:adverse effects*; D006801:Humans; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D007222:Inert Gas Narcosis / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D009569:Nitric Oxide / Q000097:blood*; D010100:Oxygen / Q000378:metabolism*; D011597:Psychomotor Performance; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide; D009569:Nitric Oxide; D010100:Oxygen
keywords: carbon dioxide; cognitive testing; diving; narcosis; nitrogen; oxygen