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Nitrogen narcosis

Geoffrey E Ciarlone, Jay B Dean
Central CO2 chemoreceptive neurons in the caudal solitary complex (cSC) are stimulated by hyperoxia via a free radical mechanism. Hyperoxia has been shown to increase superoxide and nitric oxide in the cSC, but it remains unknown how changes in Pco2 during hyperoxia affect the production of O2-dependent reactive oxygen and nitrogen species (RONS) downstream that can lead to increased levels of oxidative and nitrosative stress, cellular excitability, and, potentially, dysfunction. We used real-time fluorescence microscopy in rat brain slices to determine how hyperoxia and hypercapnic acidosis (HA) modulate one another in the production of key RONS, as well as colorimetric assays to measure levels of oxidized and nitrated lipids and proteins...
December 1, 2016: American Journal of Physiology. Cell Physiology
Geoffrey E Ciarlone, Jay B Dean
Central CO2-chemosensitive neurons in the caudal solitary complex (cSC) are stimulated not only by hypercapnic acidosis, but by hyperoxia as well. While a cellular mechanism for the CO2 response has yet to be isolated, previous data show that a redox-sensitive mechanism underlies neuronal excitability to hyperoxia. However, it remains unknown how changes in Po2 affect the production of reactive oxygen and nitrogen species (RONS) in the cSC that can lead to increased cellular excitability and, with larger doses, to cellular dysfunction and death...
December 1, 2016: American Journal of Physiology. Cell Physiology
John Jacob Freiberger, Bruce Derrick, Michael J Natoli, Igor Akushevich, Eric A Schinazi, Carl Parker, Bret W Stolp, Peter B Bennett, Richard D Vann, Sophia A S Dunworth, Richard E Moon
INTRODUCTION: Diving narcosis results from the complex interaction of gases, activities and environmental conditions. We hypothesized 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. O2 in immersed, exercising subjects while assessing multi-tasking performance with the MATB-II flight simulator. METHODS: Cognitive performance was tested under 20 conditions of gas partial pressure and exercise in 42 male subjects meeting US Navy age and fitness profiles...
September 15, 2016: Journal of Applied Physiology
Jean-Claude Rostain, Cécile Lavoute
Gases that are not metabolized by the organism are thus chemically inactive under normal conditions. Such gases include the "noble gases" of the Periodic Table as well as hydrogen and nitrogen. At increasing pressure, nitrogen induces narcosis at 4 absolute atmospheres (ATAs) and more in humans and at 11 ATA and more in rats. Electrophysiological and neuropharmacological studies suggest that the striatum is a target of nitrogen narcosis. Glutamate and dopamine release from the striatum in rats are decreased by exposure to nitrogen at a pressure of 31 ATA (75% of the anesthetic threshold)...
2016: Comprehensive Physiology
Costantino Balestra, Peter Germonpré
SCUBA diving exposes divers to decompression sickness (DCS). There has been considerable debate whether divers with a Patent Foramen Ovale of the heart have a higher risk of DCS because of the possible right-to-left shunt of venous decompression bubbles into the arterial circulation. Symptomatic neurological DCS has been shown to cause permanent damage to brain and spinal cord tissue; it has been suggested that divers with PFO may be at higher risk of developing subclinical brain lesions because of repeated asymptomatic embolization of decompression-induced nitrogen bubbles...
2016: Frontiers in Psychology
David R Pendergast, Richard E Moon, John J Krasney, Heather E Held, Paola Zamparo
Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues...
October 2015: Comprehensive Physiology
Yang-yang Li, Lu Shi, Yan-meng Zhang, Chan-juan Xiao, Hong-tao Liu
OBJECTIVE: To explore the underwater decompression schedule for 100 m Trimix conventional diving operations and evaluate its safety through a simulated rabbits Trimix conventional diving. METHODS: According to the Haldane theory, the assumed time units, the classification of tissue compartments, the nitrogen super-saturation safety coefficient and the selection of methods used for the calculation of the simulated 100 m Trimix conventional diving schedule were properly selected, and the calculating method for the dive decompression schedule was thus firmly established...
May 2015: Chinese Journal of Applied Physiology
Yu Wang, Liang Chen, Xiaogang Wang, Chaoqing Dai, Junlang Chen
The lateral pressure exerted on cell membrane is of great importance to signal transduction. Here, we perform molecular dynamics simulation to explore how lateral pressure affects the biophysical properties of lipid bilayer as well as nitrogen distribution in the membrane. Our results show that both physical properties of cell membrane and nitrogen distribution are highly sensitive to the lateral pressure. With the increasing lateral pressure, area per lipid drops and thickness of membrane increases obviously, while nitrogen molecules are more congested in the center of lipid bilayer than those under lower lateral pressure...
May 2015: Journal of Molecular Modeling
James E Clark
Exposure to the underwater environment for pleasure or work poses many challenges on the human body including thermal stress, barotraumas, decompression sickness as well as the acute effects of breathing gases under pressure. With the popularity of recreational self-contained underwater breathing apparatus (SCUBA) diving on the increase and deep inland dive sites becoming more accessible, it is important that we understand the effects of breathing pressurised gas at depth can have on the body. One of the common consequences of hyperbaric gas is the narcotic effect of inert gas...
2015: Extreme Physiology & Medicine
Charles H van Wijk, W A J Meintjes
BACKGROUND: The interaction of subjective experiences and objective measures of neuropsychological performance during hyperbaric exposure has received less attention in the literature, in part due to the shortage of available and appropriately standardized measures. OBJECTIVE: This study aimed to describe the psychometric properties of a modified version of the Subjective High Assessment Scale when used in the hyperbaric context, by exploring internal reliability, factor structure, associations with psychological variables and simple cognitive delayed recall, and the effect of task focus on the recall of subjective experience...
November 2014: Undersea & Hyperbaric Medicine: Journal of the Undersea and Hyperbaric Medical Society, Inc
Charles H van Wijk, W A J Meintjes
OBJECTIVE: Commercial diving often occurs in low visibility, where divers are reliant on their tactile senses. This study examined the effect of nitrogen narcosis on tactile memory for shapes as well as the influence of psychological and biographical factors on this relationship. METHOD: This crossover study tested 139 commercial divers in a dry hyperbaric chamber at 101.325 and 607.95 kPa (1 and 6 atmospheres absolute/atm abs). Divers memorized shapes while blindfolded, using their tactile senses only...
September 2014: Undersea & Hyperbaric Medicine: Journal of the Undersea and Hyperbaric Medical Society, Inc
Jacqueline Conger, Everett F Magann
Exercise during pregnancy has been advocated by many professional organizations to promote fetal heath and maternal well-being. Those same professional organizations do not recommend diving during pregnancy because of the potential adverse outcomes that have been observed in the animal model. In nonpregnant women, diving becomes problematic at depth as the ambient pressure increases and more gases become dissolved in the bloodstream. This can result in oxygen toxicity and nitrogen narcosis. Too rapid an ascent from depth can cause nitrogen emboli that can lodge in joints and tissue, resulting in decompression sickness, known as "the bends...
September 2014: Obstetrical & Gynecological Survey
Charles H van Wijk, Willem A J Meintjes
BACKGROUND: In a task-environment where visibility has deteriorated, individuals rely heavily on tactile performance (perception and manipulation) to complete complex tasks. When this happens under hyperbaric conditions, factors like nitrogen narcosis could influence a person's ability to successfully complete such tasks. OBJECTIVE: To examine the effect of nitrogen narcosis on a complex neuropsychological task measuring tactile performance at a pressure of 608 kPa (6 atm abs), in the absence of visual access to the task...
June 2014: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
Seichi Horie
Exposure to heat disturbs the homeostasis of body water, serum osmosis, and core temperature, resulting in the development of heat cramp, heat syncope, heat exhaustion, and heat stroke. Commonly coexisting risks are humidity, windlessness, infrared radiation, physical exertion, continuous work, chemical protective clothing, and lack of acclimatization. Exposure to cold constricts peripheral arteries and reduces metabolism, resulting in the development of chilblains, frostbite, immersion foot, and hypothermia...
February 2014: Nihon Rinsho. Japanese Journal of Clinical Medicine
Cédric Meckler, Jean-Eric Blatteau, Thierry Hasbroucq, Bruno Schmid, Jean-Jacques Risso, Franck Vidal
Certain underwater circumstances carry risk of inert gas narcosis. Impairment of sensorimotor information processing due to narcosis, induced by normobaric nitrous oxide or high partial nitrogen pressure, has been broadly evidenced, by a lengthening of the reaction time (RT). However, the locus of this effect remains a matter of debate. We examined whether inert gas narcosis affects the response-selection stage of sensorimotor information processing. We compared an air normobaric condition with a hyperbaric condition in which 10 subjects were subjected to 6 absolute atmospheres of 8...
2014: Ergonomics
Casey A Grover, David H Grover
As early as 1826, divers diving to great depths noted that descent often resulted in a phenomenon of intoxication and euphoria. In 1935, Albert Behnke discovered nitrogen as the cause of this clinical syndrome, a condition now known as nitrogen narcosis. Nitrogen narcosis consists of the development of euphoria, a false sense of security, and impaired judgment upon underwater descent using compressed air below 3-4 atmospheres (99 to 132 feet). At greater depths, symptoms can progress to loss of consciousness...
February 2014: Journal of Emergency Medicine
Leyla Ozdemir, Güler Duru-Aşiret, Burcu Bayrak-Kahraman, Nilgün Devrez, Asutay Akbayir
BACKGROUND: There is a paucity of research on diving-related health issues and associated factors. This study aimed to examine the health problems encountered during diving and to ascertain the factors associated with adverse events. METHODS: The sample of this descriptive study consisted of 132 recreational divers from diving schools in Ankara. The researchers collected the data using a questionnaire developed according to the relevant literature. RESULTS: Diving-related health issues including barotraumas, nitrogen narcosis, and decompression sickness were mostly dependent on depth...
September 2013: Journal of Travel Medicine
Simon J Mitchell, David J Doolette
Technical divers use gases other than air and advanced equipment configurations to conduct dives that are deeper and/or longer than typical recreational air dives. The use of oxygen-nitrogen (nitrox) mixes with oxygen fractions higher than air results in longer no-decompression limits for shallow diving, and faster decompression from deeper dives. For depths beyond the air-diving range, technical divers mix helium, a light non-narcotic gas, with nitrogen and oxygen to produce 'trimix'. These blends are tailored to the depth of intended use with a fraction of oxygen calculated to produce an inspired oxygen partial pressure unlikely to cause cerebral oxygen toxicity and a nitrogen fraction calculated to produce a tolerable degree of nitrogen narcosis...
June 2013: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
Wendy Kneller, Malcolm Hobbs
Previous research has consistently demonstrated that inert gas (nitrogen) narcosis affects free recall but not recognition memory in the depth range of 30 to 50 meters of sea water (msw), possibly as a result of narcosis preventing processing when learned material is encoded. The aim of the current research was to test this hypothesis by applying a levels of processing approach to the measurement of free recall under narcosis. Experiment 1 investigated the effect of depth (0-2 msw vs. 37-39 msw) and level of processing (shallow vs...
May 2013: Undersea & Hyperbaric Medicine: Journal of the Undersea and Hyperbaric Medical Society, Inc
David J Doolette, Simon J Mitchell
Exposure to elevated ambient pressure (hyperbaric conditions) occurs most commonly in underwater diving, during which respired gas density and partial pressures, work of breathing, and physiological dead space are all increased. There is a tendency toward hypercapnia during diving, with several potential causes. Most importantly, there may be reduced responsiveness of the respiratory controller to rising arterial CO₂, leading to hypoventilation and CO₂ retention. Contributory factors may include elevated arterial PO₂, inert gas narcosis and an innate (but variable) tendency of the respiratory controller to sacrifice tight control of arterial CO₂ when work of breathing increases...
January 2011: Comprehensive Physiology
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