157 results on '"inert gas narcosis"'
Search Results
2. Selective impairment by nitrogen narcosis of performance on a digit-copying and a mental task.
- Author
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Synodinos NE
- Subjects
- Adult, Humans, Male, Inert Gas Narcosis, Mental Processes, Motor Skills, Nitrogen
- Published
- 1976
- Full Text
- View/download PDF
3. PHARMACOLOGY IN HYPERBARIC OXYGENATION. INERT GAS NARCOSIS.
- Author
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FENN WO
- Subjects
- Animals, Argon, Atmospheric Pressure, Drosophila, Helium, Hyperbaric Oxygenation, Inert Gas Narcosis, Metabolism, Nitrogen, Oxygen, Pharmacology, Respiration, Toxicology
- Published
- 1965
4. Tensional changes of alveolar gas in reactions to rapid compression and decompression and question of nitrogen narcosis.
- Author
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BEAN JW
- Subjects
- Decompression, Inert Gas Narcosis, Lung, Nitrogen, Nitrogen Compounds, Pressure, Respiration
- Published
- 1950
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5. Relative narcotic potencies of hydrogen, helium, nitrogen, and their mixtures.
- Author
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Brauer RW and Way RO
- Subjects
- Animals, Diving, Female, Mice, Pressure, Species Specificity, Central Nervous System drug effects, Helium pharmacology, Hydrogen pharmacology, Inert Gas Narcosis, Nitrogen pharmacology, Nitrous Oxide pharmacology
- Published
- 1970
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6. Measurement and mechanisms of inert gas narcosis.
- Author
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Bennett PB
- Subjects
- Humans, Inert Gas Narcosis, Male, Diving, Helium, Nitrogen
- Published
- 1969
7. [The various stages of nitrogen narcosis in the albino rat. EEG study. Preliminary note].
- Author
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ALBANO G, CRISCUOLI PM, and COPPOLINO CB
- Subjects
- Animals, Rats, Anesthesia, Atmospheric Pressure, Electroencephalography, Inert Gas Narcosis, Nitrogen, Respiration
- Published
- 1962
8. [Narcotic power of nitrogen protoxide examined on various nervous structures].
- Author
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Dolivo M, Foroglou C, and Posternak JM
- Subjects
- Animals, Electrophysiology, In Vitro Techniques, Oxides pharmacology, Rats, Vagus Nerve drug effects, Ganglia, Autonomic drug effects, Inert Gas Narcosis, Nitrogen pharmacology, Phrenic Nerve drug effects
- Published
- 1970
9. Growth of Streptococcus faecalis under high hydrostatic pressure and high partial pressures of inert gases.
- Author
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Fenn WO and Marquis RE
- Subjects
- Glycolysis, Helium pharmacology, Inert Gas Narcosis, Lactates metabolism, Oxygen pharmacology, Partial Pressure, Pressure, Time Factors, Water, Argon pharmacology, Enterococcus faecalis growth & development, Nitrogen pharmacology, Nitrous Oxide pharmacology, Xenon pharmacology
- Abstract
Growth of Streptococcus faecalis in a complex medium was inhibited by xenon, nitrous oxide, argon, and nitrogen at gas pressures of 41 atm or less. The order of inhibitory potency was: xenon and nitrous oxide > argon > nitrogen. Helium appeared to be impotent. Oxygen also inhibited streptococcal growth and it acted synergistically with narcotic gases. Growth was slowed somewhat by 41 atm hydrostatic pressure in the absence of narcotic gases, but the gas effects were greater than those due to pressure. In relation to the sensitivity of this bacterium to pressure, we found that the volume of cultures increased during growth in a volumeter or dilatometer, and that this dilatation was due mainly to glycolysis. A volume increase of 20.3 +/- 3.6 ml/mole of lactic acid produced was measured, and this value was close to one of 24 ml/mole lactic acid given for muscle glycolysis, and interestingly, close to the theoretic volume increase of activation calculated from the depression of growth rate by pressure.
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- 1968
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10. The prevention of decompression sickness and nitrogen narcosis by the use of hydrogen as a substitute for nitrogen, the Arne Zetterstrôm method for deep-sea diving.
- Author
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BJURSTEDT H and SEVERIN G
- Subjects
- Humans, Decompression Sickness, Diving, Hydrogen, Inert Gas Narcosis, Nitrogen
- Published
- 1948
11. Nitrogen narcosis during a 14-day continuous exposure to 5.2 per cent O 2 in N 2 at pressure equivalent to 100 FSW (4 ATA).
- Author
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Elcombe DD and Teeter JH
- Subjects
- Adult, Atmosphere Exposure Chambers, Citrates, Cognition, Diving, Environmental Exposure, Glucose, Humans, Intelligence, Male, Memory, Methods, Quinine, Seawater, Smell, Sodium Chloride, Taste, Time Factors, Atmospheric Pressure, Inert Gas Narcosis, Nitrogen, Oxygen
- Published
- 1973
12. Some comments on "a behavioral approach to nitrogen narcosis".
- Author
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Fowler B
- Subjects
- Atmosphere Exposure Chambers, Atmospheric Pressure, Diving, Helium, Humans, Immersion, Task Performance and Analysis, Behavior, Inert Gas Narcosis, Nitrogen
- Published
- 1972
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- View/download PDF
13. MILD NITROGEN NARCOSIS?
- Author
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POULTON EC, CARPENTER A, and CATTON MJ
- Subjects
- Humans, Atmospheric Pressure, Diving, Inert Gas Narcosis, Mental Processes, Nitrogen, Respiration
- Published
- 1963
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14. Nitrogen, helium, and neon effects on timing behavior at increased pressures.
- Author
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Thomas JR
- Subjects
- Animals, Atmosphere Exposure Chambers, Male, Rats, Reaction Time, Reinforcement Schedule, Atmospheric Pressure, Discrimination Learning drug effects, Helium toxicity, Inert Gas Narcosis, Neon toxicity, Nitrogen toxicity, Time Perception
- Published
- 1973
15. Nitrogen narcosis in frogs and mice.
- Author
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MARSHALL JM
- Subjects
- Animals, Mice, Anesthesia, Anesthesia, Inhalation, Anesthesiology, Anura, Inert Gas Narcosis, Nitrogen
- Published
- 1951
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- View/download PDF
16. Multiday exposure to 5.2 per cent O 2 at 4 ATA. Scope of program.
- Author
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Lambertsen CJ and Wright WB
- Subjects
- Adult, Airway Resistance, Atmosphere Exposure Chambers, Blood Chemical Analysis, Blood Circulation, Blood Volume, Body Fluids, Carbon Dioxide, Diving, Environmental Exposure, Helium, Humans, Inert Gas Narcosis, Lung physiology, Male, Posture, Respiration, Seawater, Time Factors, Adaptation, Physiological, Atmospheric Pressure, Nitrogen, Oxygen
- Published
- 1973
17. Blood nitrogen tensions of seals during simulated deep dives.
- Author
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Kooyman GL, Schroeder JP, Denison DM, Hammond DD, Wright JJ, and Bergman WP
- Subjects
- Animals, Atmosphere Exposure Chambers, Decompression Sickness physiopathology, Female, Immersion, Inert Gas Narcosis, Male, Naval Medicine, Partial Pressure, Plethysmography, Whole Body, Pulmonary Alveoli physiopathology, Pulmonary Circulation, Respiration, Species Specificity, Spirometry, Ventilation-Perfusion Ratio, Caniformia physiology, Diving, Nitrogen blood
- Published
- 1972
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18. Comparison of the effects of drugs on nitrogen narcosis and oxygen toxicity in rats.
- Author
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BENNETT PB
- Subjects
- Animals, Rats, Bemegride, Carbachol, Epinephrine, Glutethimide, Hyperoxia, Inert Gas Narcosis, Methamphetamine, Nitrogen, Oxygen, Pentylenetetrazole, Phenacetin, Physostigmine, Piperidines, Scopolamine
- Published
- 1962
- Full Text
- View/download PDF
19. Performance impairment as a function of nitrogen narcosis. 3-60.
- Author
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KIESSLING RJ and MAAG CH
- Subjects
- Diving, Inert Gas Narcosis, Nitrogen toxicity
- Published
- 1960
20. World as it is: Drinker driver flyer diver.
- Author
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Laden, Gerard and Mathew, Bruce
- Subjects
BLOOD alcohol ,COGNITIVE ability ,INERT gas narcosis ,DECISION making ,SCUBA diving - Abstract
Blood alcohol concentrations above defined levels are detrimental to cognitive performance. Empirical and published evidence suggest that nitrogen narcosis is analogous to alcohol intoxication with both impairing prefrontal cortex function. Nitrogen narcosis is also known to have been a factor in fatal accidents. To examine the effects of nitrogen narcosis, a recent publication used the Iowa Gambling Task tool, to simulate dynamic real-life risky decision-making behaviour. If the reported outcomes are corroborated in larger rigorously designed studies it is likely to provide further evidence that divers may well experience the negative effects of a 'narcotic agent', even at relatively shallow depths. These deleterious effects may occur regardless of diving experience, aptitude or professional status. In 1872, English law made it an offence to be 'drunk' whilst in charge of horses, carriages, cattle and steam engines. Understanding the danger was easy, establishing who is 'drunk' in the eyes of the court required a legal definition. Driving above a 'legal limit' for alcohol was made illegal in the United Kingdom in 1967. The limit was set at 80 milligrams of alcohol per 100 millilitres of blood. It took just short of one hundred years to get from first introducing a restriction to specific activities, whilst under the influence of alcohol, to having a clear and well-defined enforceable law. The question surely is whether our modern society will tolerate another century before legally defining safe parameters for nitrogen narcosis? [ABSTRACT FROM AUTHOR]
- Published
- 2024
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21. Pupillometry is not sensitive to gas narcosis in divers breathing hyperbaric air or normobaric nitrous oxide.
- Author
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Vrijdag, Xavier C. E., van Waart, Hanna, Sleigh, Jamie W., and Mitchell, Simon J.
- Subjects
PUPILLOMETRY ,INERT gas narcosis ,DIVERS ,HYPERBARIC oxygenation ,ANESTHESIA - Abstract
Introduction: Gas narcosis impairs divers when diving deeper. Pupillometry is sensitive to alcohol intoxication and it has been used in anaesthesia to assess nitrous oxide narcosis. It is a potential novel method to quantify narcosis in diving. The aim of this study was to evaluate pupillometry for objective measurement of narcosis during exposure to hyperbaric air or nitrous oxide. Method: Pupil size in 16 subjects was recorded directly at surface pressure and during air breathing at 608 kPa (equivalent to 50 metres’ seawater depth) in a hyperbaric chamber. Another 12 subjects were exposed to nitrous oxide at end-tidal percentages of 20, 30 and 40% in random order at surface pressure. Pupil size and pupil light reflex were recorded at baseline and at each level of nitrous oxide exposure. Results: Pupil size did not significantly change during exposure to hyperbaric air or nitrous oxide. The pupil light reflex, evaluated using percentage constriction and minimum diameter after exposure to a light stimulus, was affected significantly only during the highest nitrous oxide exposure – an end-tidal level of 40%. Conclusion: Pupillometry is insensitive to the narcotic effect of air at 608 kPa in the dry hyperbaric environment and to the effects of low dose nitrous oxide. Pupillometry is not suitable as a monitoring method for gas narcosis in diving. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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22. Inert gas narcosis in scuba diving, different gases different reactions.
- Author
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Rocco, Monica, Pelaia, P., Di Benedetto, P., Conte, G., Maggi, L., Fiorelli, S., Mercieri, M., Balestra, C., De Blasi, R. A., and ROAD Project Investigators
- Subjects
- *
INERT gas narcosis , *SCUBA divers , *FLICKER fusion , *GABA receptors , *EXCITATION (Physiology) , *PHYSIOLOGICAL aspects of cognition , *AROUSAL (Physiology) , *BRAIN , *DIVING , *GASES , *HELIUM , *NITROGEN , *RESEARCH funding , *VISUAL perception - Abstract
Purpose: Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver's safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release.Methods: Sixty experienced divers breathing Air, Trimix or Heliox, were studied during an open water dive to a depth of 6 ATA with a square profile testing CFFF measurement before (T0), during the dive upon arriving at the bottom (6 ATA) (T1), 20 min of bottom time (T2), and at 5 m (1.5 ATA) (T3).Results: CFFF results showed a slight increase in alertness and arousal during the deep dive regardless of the gas mixture breathed. The percent change in CFFF values at T1 and T2 differed among the three groups being lower in the air group than in the other groups. All CFFF values returned to basal values 5 min before the final ascent at 5 m (T3), but the Trimix measurements were still slightly better than those at T0.Conclusions: Our results highlight that nitrogen and oxygen alone and in combination can produce neuronal excitability or depression in a dose-related response. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
23. EEG functional connectivity is sensitive for nitrogen narcosis at 608 kPa
- Author
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Xavier C E, Vrijdag, Hanna, van Waart, Rebecca M, Pullon, Chris, Sames, Simon J, Mitchell, and Jamie W, Sleigh
- Subjects
Oxygen ,Inert Gas Narcosis ,Nitrogen ,Diving ,Humans ,Electroencephalography ,Female ,Stupor ,Helium - Abstract
Divers commonly breathe air, containing nitrogen. Nitrogen under hyperbaric conditions is a narcotic gas. In dives beyond a notional threshold of 30 m depth (405 kPa) this can cause cognitive impairment, culminating in accidents due to poor decision making. Helium is known to have no narcotic effect. This study explored potential approaches to developing an electroencephalogram (EEG) functional connectivity metric to measure narcosis produced by nitrogen at hyperbaric pressures. Twelve human participants (five female) breathed air and heliox (in random order) at 284 and 608 kPa while recording 32-channel EEG and psychometric function. The degree of spatial functional connectivity, estimated using mutual information, was summarized with global efficiency. Air-breathing at 608 kPa (experienced as mild narcosis) caused a 35% increase in global efficiency compared to surface air-breathing (mean increase = 0.17, 95% CI [0.09-0.25], p = 0.001). Air-breathing at 284 kPa trended in a similar direction. Functional connectivity was modestly associated with psychometric impairment (mixed-effects model r
- Published
- 2021
24. Assessment of Alertness and Cognitive Performance of Closed Circuit Rebreather Divers With the Critical Flicker Fusion Frequency Test in Arctic Diving Conditions
- Author
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Piispanen, Wilhelm W., Lundell, Richard V., Tuominen, Laura J., Räisänen-Sokolowski, Anne K., Tampere University, Department of Prehospital Emergency Care, Pain Management and Anaesthesiology, Department of Pathology, Medicum, and HUSLAB
- Subjects
arctic diving ,AIR ,ATTENTION ,THERMAL STATUS ,inert gas narcosis ,IMPAIRMENT ,3126 Surgery, anesthesiology, intensive care, radiology ,OXYGEN ,NITROGEN ,HYPEROXIA ,EXCITABILITY ,thermal control ,mixed gas diving ,3111 Biomedicine ,GAS NARCOSIS ,human activities ,technical diving ,TEMPERATURE - Abstract
Introduction: Cold water imposes many risks to the diver. These risks include decompression illness, physical and cognitive impairment, and hypothermia. Cognitive impairment can be estimated using a critical flicker fusion frequency (CFFF) test, but this method has only been used in a few studies conducted in an open water environment. We studied the effect of the cold and a helium-containing mixed breathing gas on the cognition of closed circuit rebreather (CCR) divers. Materials and Methods: Twenty-three divers performed an identical dive with controlled trimix gas with a CCR device in an ice-covered quarry. They assessed their thermal comfort at four time points during the dive. In addition, their skin temperature was measured at 5-min intervals throughout the dive. The divers performed the CFFF test before the dive, at target depth, and after the dive. Results: A statistically significant increase of 111.7% in CFFF values was recorded during the dive compared to the pre-dive values (p < 0.0001). The values returned to the baseline after surfacing. There was a significant drop in the divers’ skin temperature of 0.48°C every 10 min during the dive (p < 0.001). The divers’ subjectively assessed thermal comfort also decreased during the dive (p = 0.01). Conclusion: Our findings showed that neither extreme cold water nor helium-containing mixed breathing gas had any influence on the general CFFF profile described in the previous studies from warmer water and where divers used other breathing gases. We hypothesize that cold-water diving and helium-containing breathing gases do not in these diving conditions cause clinically relevant cerebral impairment. Therefore, we conclude that CCR diving in these conditions is safe from the perspective of alertness and cognitive performance. publishedVersion
- Published
- 2021
25. A comparison of simple reaction time, visual discrimination and critical flicker fusion frequency in professional divers at elevated pressure.
- Author
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Tikkinen, Janne, Wuorimaa, Tomi, and Siimes, Martti A.
- Subjects
INERT gas narcosis ,HYPERBARIC chambers ,REACTION time ,VISUAL discrimination ,COGNITIVE testing - Abstract
Introduction: Inert gas narcosis (IGN) impairs cognitive performance and some divers are more susceptible to IGN than others. We compared the sensitivity of two reaction time tests to detect changes in performance at pressure and compared these results with critical flicker fusion frequency (CFF) changes at the same ambient pressures. Methods: The study assessed simple reaction time (RT), mean time correct of the discrimination reaction time (MTC) and CFF in 30 professional divers breathing air at 101 kPa and 608 kPa in a hyperbaric chamber. Results: RT and MTC increased at 608 kPa by 5.1 ± 9.4% (P = 0.04) and 7.3 ± 12.3% (P = 0.01) respectively. RT decreased to pre-compression level after decompression and MTC decreased to a level lower than pre-compression (P < 0.001) values. CFF increased by 2.5 ± 2.8% (P < 0.001) at 608 kPa. CFF decreased to pre-compression level after decompression. An increase in CFF was inversely correlated with a decrease in RT (r = 0.38, P = 0.04) and in MTC (r = 0.43, P = 0.02) at 608 kPa. Conclusions: Response speeds of the same subjects were impaired in both reaction time tasks at 608 kPa, whereas CFF increased at depth. An association between changes in response times and changes in CFF suggests that divers susceptible to IGN may also be susceptible to the effects of elevated oxygen partial pressure. If this holds true, the future selection of professional divers could be improved by the use of simple cognitive tests. [ABSTRACT FROM AUTHOR]
- Published
- 2016
26. Dopamine-dependent biphasic behaviour under ‘deep diving’ conditions in Caenorhabditis elegans
- Author
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Eyal Itskovits, Ben Aviner, Limor Broday, Alon Zaslaver, and Inbar Kirshenboim
- Subjects
Nitrogen ,Dopamine ,Partial Pressure ,Mutant ,hyperbaric chamber ,Helium ,General Biochemistry, Genetics and Molecular Biology ,dat-1 ,03 medical and health sciences ,nitrogen narcosis ,0302 clinical medicine ,Extracellular ,medicine ,Animals ,Behaviour ,Nitrogen narcosis ,Caenorhabditis elegans ,cat-2 ,Research Articles ,030304 developmental biology ,General Environmental Science ,0303 health sciences ,General Immunology and Microbiology ,biology ,Chemistry ,General Medicine ,Partial pressure ,medicine.disease ,biology.organism_classification ,Scuba diving ,Inert Gas Narcosis ,Toxicity ,Biophysics ,C. elegans ,General Agricultural and Biological Sciences ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Underwater divers are susceptible to neurological risks due to their exposure to increased pressure. Absorption of elevated partial pressure of inert gases such as helium and nitrogen may lead to nitrogen narcosis. Although the symptoms of nitrogen narcosis are known, the molecular mechanisms underlying these symptoms have not been elucidated. Here, we examined the behaviour of the soil nematode Caenorhabditis elegans under scuba diving conditions. We analysed wild-type animals and mutants in the dopamine pathway under hyperbaric conditions, using several gas compositions and under varying pressure levels. We found that the animals changed their speed on a flat bacterial surface in response to pressure in a biphasic mode that depended on dopamine. Dopamine-deficient cat-2 mutant animals did not exhibit a biphasic response in high pressure, while the extracellular accumulation of dopamine in dat-1 mutant animals mildly influenced this response. Our data demonstrate that in C. elegans , similarly to mammalian systems, dopamine signalling is involved in the response to high pressure. This study establishes C. elegans as a powerful system to elucidate the molecular mechanisms that underly nitrogen toxicity in response to high pressure.
- Published
- 2021
27. INFLUENCE OF HYPERBARIC BREATHING GASES ON DEEP DIVERS.
- Author
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STANCIU, Tamara and ADUMITRESI, Cecilia
- Subjects
- *
DEEP diving -- Physiological aspects , *HYPERBARIC oxygenation , *HYPERBARIC chambers , *INERT gas narcosis , *HYPOTHERMIA - Abstract
The ability of a diver to pass the deep diving course is tested through trials that evaluate the tolerance of a diver to hyperbaric respiratory gases. Three of these tests take place in the hyperbaric chamber in order to highlight the effect of oxygen and inert gases over the diver, during pressurization. These are: the Oxygen test, the Narcosis test and HPNS (High Pressure Nervous Syndrome). If the first two tests are frequently executed, HPNS was resumed and improved at Hyperbaric Complex of Diving Center. Hypothermia is another stress factor in the hyperbaric environment that has been studied and was identified by a series of dives at different depths of immersion in wet simulator of Diving Center. The experimental results were consistent with calculated temperature losses previously established by mathematical model. [ABSTRACT FROM AUTHOR]
- Published
- 2015
28. Effects of hyperbaric nitrogen-induced narcosis on response-selection processes.
- Author
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Meckler, Cédric, Blatteau, Jean-Eric, Hasbroucq, Thierry, Schmid, Bruno, Risso, Jean-Jacques, and Vidal, Franck
- Subjects
ANALYSIS of variance ,DIVING ,NITROGEN ,REACTION time ,MILITARY personnel ,TASK performance ,REPEATED measures design - Abstract
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 8.33% O2Nitrox. In both conditions, subjects performed a between-hand choice-RT task in which we explicitly manipulated the stimulus–response association rule. The effect of this manipulation (which is supposed to affect response-selection processes) was modified by inert gas narcosis. It is concluded, therefore, that response selection processes are among the loci involved in the effect of inert gas narcosis on information processing. Practitioner Summary:Does inert gas narcosis affect the response-selection stage of sensorimotor-information processing? Subjects performed a RT task in which response-selection processes were explicitly manipulated. The well-known ‘compatibility’ effect was modified by inert gas narcosis compared with control condition: response-selection processes are among the loci involved in the effect of inert gas narcosis on information processing. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
29. Inhibition of NR2B-containing NMDA receptors during nitrogen narcosis
- Author
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Du-Du Hao, Guo-Hua Wang, Xia Li, Zheng-Lin Jiang, Zong-Yu Guan, and Bin Peng
- Subjects
0301 basic medicine ,medicine.medical_specialty ,Nitrogen ,Diving ,Hippocampus ,Stimulation ,Hippocampal formation ,CREB ,Receptors, N-Methyl-D-Aspartate ,03 medical and health sciences ,Cerebellar Cortex ,Mice ,0302 clinical medicine ,Internal medicine ,medicine ,Premovement neuronal activity ,Animals ,Humans ,Nitrogen narcosis ,Neurons ,biology ,Chemistry ,Public Health, Environmental and Occupational Health ,Electroencephalography ,medicine.disease ,030104 developmental biology ,medicine.anatomical_structure ,Endocrinology ,Atmospheric Pressure ,nervous system ,Inert Gas Narcosis ,biology.protein ,NMDA receptor ,Original Article ,Neuron ,030217 neurology & neurosurgery - Abstract
INTRODUCTION: When humans breathe compressed air or N(2)-O(2) mixtures at three to four atmospheres pressure, they will experience nitrogen narcosis that may possibly lead to a diving accident, but the underlying mechanisms remain unclear. METHODS: Mice were exposed to 1.6 MPa breathing a N(2)-O(2) mixture adjusted to deliver an inspired PO(2) of 32–42 kPa. The electroencephalogram (EEG) and forced swimming test were used to evaluate the narcotic effect of nitrogen. Neuronal activity was observed via c-Fos expression in cortex and hippocampus tissue after decompressing to the surface. To further investigate underlying molecular mechanisms, we incubated cultured hippocampal neurons with various NMDA concentrations, and measured expression of NMDA receptors and its down-stream signal with or without 1.6 MPa N(2)-O(2) exposure. RESULTS: Both the frequency of the EEG and the drowning time using the forced swimming test were significantly decreased during exposure to 1.6 MPa N(2)-O(2) (P < 0.001). Additionally, in cultured hippocampal neurons, the increased levels of phosphorylated NR2B and cAMP-response element binding protein (CREB) induced by NMDA stimulation were significantly inhibited by exposure to 1.6 MPa N(2)-O(2). CONCLUSION: Our findings indicated that NR2B-containing NMDA receptors were inhibited during nitrogen narcosis.
- Published
- 2019
30. Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox
- Author
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Peter Germonpré, Pierre Lafère, Peter Buzzacott, Walter Hemelryck, Costantino Balestra, Physiotherapy, Human Physiology and Anatomy, and Anatomical Research and Clinical Studies
- Subjects
cognition ,Nitrox ,task performance and analysis ,Cardiologie et circulation ,Diving ,Poison control ,Hygiène et médecine sportives ,Audiology ,Cognition ,0302 clinical medicine ,Task Performance and Analysis ,Oxygen/therapeutic use ,050107 human factors ,Air ,Respiration ,05 social sciences ,Education physique ,Inert Gas Narcosis -- prevention & control -- psychology ,General Medicine ,Sciences bio-médicales et agricoles ,Breathing gas ,RESPIRATION ,Médecine de l'environnement ,Breathing ,Inert Gas Narcosis ,Inert Gas Narcosis/prevention & control ,diving ,Adult ,Test battery ,medicine.medical_specialty ,Nitrogen ,air ,03 medical and health sciences ,Double-Blind Method ,Hum ,medicine ,Humans ,0501 psychology and cognitive sciences ,Effects of sleep deprivation on cognitive performance ,Nitrogen -- therapeutic use ,business.industry ,Médecine pathologie humaine ,Nitrogen/therapeutic use ,030229 sport sciences ,Oxygen ,Oxygen -- therapeutic use ,Hygiène et médecine du travail ,business ,human activities - Abstract
Divers try to limit risks associated with their sport, for instance by breathing enriched air nitrox (EANx) instead of air. This double blinded, randomized trial was designed to see if the use of EANx could effectively improve cognitive performance while diving., info:eu-repo/semantics/published
- Published
- 2017
31. Effects of repeated hyperbaric nitrogen–oxygen exposures on the striatal dopamine release and on motor disturbances in rats
- Author
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Lavoute, Cécile, Weiss, Michel, and Rostain, Jean-Claude
- Subjects
- *
HYPERBARIC oxygenation , *NITROGEN , *NEUROTRANSMITTERS , *AMINO acid neurotransmitters - Abstract
Abstract: Previous studies have demonstrated disruptions of motor activities and a decrease of extracellular dopamine level in the striatum of rats exposed to high pressure of nitrogen. Men exposed to nitrogen pressure develop also motor and cognitive disturbances related to inert gas narcosis. After repetitive exposures, adaptation to narcosis was subjectively reported. To study the effects of repetitive exposures to hyperbaric nitrogen–oxygen, male Sprague–Dawley rats were implanted in the striatum with multifiber carbon dopamine-sensitive electrodes. After recovery from surgery, free-moving rats were exposed for 2 h up to 3 MPa of nitrogen–oxygen mixture before and after one daily exposure to 1 MPa of nitrogen–oxygen, for 5 consecutive days. Dopamine release was measured by differential pulse voltammetry and motor activities were quantified using piezo-electric captor. At the first exposure to 3 MPa, the striatal dopamine level decreased during the compression (−15%) to reach −20% during the stay at 3 MPa. Motor activities were increased during compression (+15%) and the first 60 min at constant pressure (+10%). In contrast, at the second exposure to 3 MPa, an increase of dopamine of +15% was obtained during the whole exposure. However, total motor activities remained unchanged as compared to the first exposure. Our results confirm that nitrogen exposure at 3 MPa led to a decreased striatal dopamine release and increased motor disturbances in naïve rats. Repetitive exposures to 1 MPa of nitrogen induced a reversal effect on the dopamine release which suggests a neurochemical change at the level of the neurotransmitter regulation processes of the basal ganglia. In contrast, motor activity remained quantitatively unchanged, thus suggesting that dopamine is not involved alone in modulating these motor disturbances. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
32. Diving emergencies
- Author
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DeGorordo, Antonio, Vallejo-Manzur, Federico, Chanin, Katia, and Varon, Joseph
- Subjects
- *
DIVERS , *INERT gas narcosis , *NITROGEN , *DIVING equipment - Abstract
Self-Contained Underwater Breathing Apparatus (SCUBA) diving popularity is increasing tremendously, reaching a total of 9 million people in the US during 2001, and 50,000 in the UK in 1985. Over the past 10 years, new advances, equipment improvements, and improved diver education have made SCUBA diving safer and more enjoyable. Most diving injuries are related to the behaviour of the gases and pressure changes during descent and ascent. The four main pathologies in diving medicine include: barotrauma (sinus, otic, and pulmonary); decompression illness (DCI); pulmonary edema and pharmacological; and toxic effects of increased partial pressures of gases. The clinical manifestations of a diving injury may be seen during a dive or up to 24 h after it. Physicians living far away from diving places are not excluded from the possibility of encountering diver-injured patients and therefore need to be aware of these injuries. This article reviews some of the principles of diving and pathophysiology of diving injuries as well as the acute treatment, and further management of these patients. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
33. Striatal dopamine release and biphasic pattern of locomotor and motor activity under gas narcosis
- Author
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Balon, Norbert, Risso, Jean-Jacques, Blanc, François, Rostain, Jean-Claude, and Weiss, Michel
- Subjects
- *
INERT gas narcosis , *NITROGEN - Abstract
Inert gas narcosis is a neurological syndrome appearing when humans or animals are exposed to hyperbaric inert gases (nitrogen, argon) composed by motor and cognitive impairments. Inert gas narcosis induces a decrease of the dopamine release at the striatum level, structure involved in the regulation of the extrapyramidal motricity. We have investigated, in freely moving rats exposed to different narcotic conditions, the relationship between the locomotor and motor activity and the striatal dopamine release, using respectively a computerized device that enables a quantitative analysis of this behavioural disturbance and voltammetry. The use of 3 MPa of nitrogen, 2 MPa of argon and 0.1 MPa of nitrous oxide, revealed after a transient phase of hyperactivity, a lower level of the locomotor and motor activity, in relation with the decrease of the striatal dopamine release. It is concluded that the striatal dopamine decrease could be related to the decrease of the locomotor and motor hyperactivity, but that other(s) neurotransmitter(s) could be primarily involved in the behavioural motor disturbances induced by narcotics. This biphasic effect could be of major importance for future pharmacological investigations, and motor categorization, on the basic mechanisms of inert gas at pressure. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
34. Pupillometry is not sensitive to gas narcosis in divers breathing hyperbaric air or normobaric nitrous oxide
- Author
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Hanna van Waart, Xavier C. E. Vrijdag, Simon J Mitchell, and Jamie W. Sleigh
- Subjects
inorganic chemicals ,Male ,Diving ,Nitrous Oxide ,chemistry.chemical_element ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,030202 anesthesiology ,Humans ,Seawater ,Monitoring methods ,Stupor ,Air breathing ,Respiration ,Low dose ,Public Health, Environmental and Occupational Health ,Objective measurement ,Pupil size ,Nitrous oxide ,Nitrogen ,chemistry ,Inert Gas Narcosis ,Anesthesia ,Original Article ,030217 neurology & neurosurgery ,Pupillometry - Abstract
Introduction Gas narcosis impairs divers when diving deeper. Pupillometry is sensitive to alcohol intoxication and it has been used in anaesthesia to assess nitrous oxide narcosis. It is a potential novel method to quantify narcosis in diving. The aim of this study was to evaluate pupillometry for objective measurement of narcosis during exposure to hyperbaric air or nitrous oxide. Method Pupil size in 16 subjects was recorded directly at surface pressure and during air breathing at 608 kPa (equivalent to 50 metres' seawater depth) in a hyperbaric chamber. Another 12 subjects were exposed to nitrous oxide at end-tidal percentages of 20, 30 and 40% in random order at surface pressure. Pupil size and pupil light reflex were recorded at baseline and at each level of nitrous oxide exposure. Results Pupil size did not significantly change during exposure to hyperbaric air or nitrous oxide. The pupil light reflex, evaluated using percentage constriction and minimum diameter after exposure to a light stimulus, was affected significantly only during the highest nitrous oxide exposure - an end-tidal level of 40%. Conclusion Pupillometry is insensitive to the narcotic effect of air at 608 kPa in the dry hyperbaric environment and to the effects of low dose nitrous oxide. Pupillometry is not suitable as a monitoring method for gas narcosis in diving.
- Published
- 2019
35. Early detection of diving-related cognitive impairment of different nitrogen-oxygen gas mixtures using critical flicker fusion frequency
- Author
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Lyubisa Matity, Peter Germonpré, Walter Hemelryck, Costantino Balestra, François Guerrero, Pierre Lafère, Physiotherapy, Human Physiology and Anatomy, and Anatomical Research and Clinical Studies
- Subjects
Nitrox ,medicine.medical_specialty ,Nitrogen ,Cognitive Dysfunction/chemically induced ,Diving ,Hygiène et médecine sportives ,Enriched air – nitrox ,Flicker fusion threshold ,010501 environmental sciences ,Audiology ,flicker fusion ,01 natural sciences ,Arousal ,Flicker Fusion ,03 medical and health sciences ,Diving/adverse effects ,0302 clinical medicine ,Near-infrared spectroscopy ,Nitrogen -- administration & dosage -- adverse effects ,Oxygen/administration & dosage ,medicine ,Humans ,Cognitive Dysfunction ,Prefrontal cortex ,0105 earth and related environmental sciences ,Cognitive Dysfunction -- chemically induced ,Narcosis ,Oxygen -- administration & dosage -- adverse effects ,Diving -- adverse effects ,Public Health, Environmental and Occupational Health ,Médecine pathologie humaine ,Education physique ,Partial pressure ,Oxygenation ,Sciences bio-médicales et agricoles ,030210 environmental & occupational health ,Nitrogen/administration & dosage ,Oxygen ,Risk management ,Médecine de l'environnement ,Breathing ,Inert Gas Narcosis ,Original Article - Abstract
Cognitive impairment related to inert gas narcosis (IGN) is a threat to diving safety and operations at depth that might be reduced by using enriched air nitrox (EANx) mixtures. Using critical flicker fusion frequency (CFFF), a possible early detection of cognitive abilities/cerebral arousal impairment when breathing different oxygen (O2) fractions was investigated., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2019
36. Inert gas narcosis in scuba diving, different gases different reactions
- Author
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Monica, Rocco, P, Pelaia, P, Di Benedetto, G, Conte, L, Maggi, S, Fiorelli, M, Mercieri, C, Balestra, R A, De Blasi, S, Mesa, Clinical sciences, Physiotherapy, Human Physiology and Anatomy, and Anatomical Research and Clinical Studies
- Subjects
Male ,Nitrogen -- adverse effects ,Physiology ,Diving ,Hygiène et médecine sportives ,030204 cardiovascular system & hematology ,flicker fusion ,Nitrogen narcosis ,Helium ,Heliox ,Oxygen ,Trimix ,Flicker Fusion ,Diving/adverse effects ,0302 clinical medicine ,arousal ,Inert Gas Narcosis/physiopathology ,Orthopedics and Sports Medicine ,Brain/drug effects ,Chemistry ,Education physique ,Brain ,General Medicine ,Sciences bio-médicales et agricoles ,Middle Aged ,Breathing gas ,Scuba diving ,Anesthesia ,Médecine de l'environnement ,Breathing ,critical flicker fusion frequency ,divers’ safety ,gaba receptors ,nitrogen narcosis ,Inert Gas Narcosis ,Inert Gas Narcosis -- physiopathology ,Diving -- adverse effects -- physiology ,Arousal ,GABA receptors ,Adult ,Nitrogen ,chemistry.chemical_element ,Anesthésiologie ,Critical flicker fusion frequency ,Brain -- drug effects ,03 medical and health sciences ,Physiology (medical) ,medicine ,Helium -- adverse effects ,Humans ,Public Health, Environmental and Occupational Health ,Helium/adverse effects ,Médecine pathologie humaine ,medicine.disease ,Nitrogen/adverse effects ,Divers’ safety ,human activities ,030217 neurology & neurosurgery - Abstract
Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver's safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release., info:eu-repo/semantics/published
- Published
- 2019
37. Neurochemistry of Pressure‐Induced Nitrogen and Metabolically Inert Gas Narcosis in the Central Nervous System
- Author
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Jean-Claude Rostain and Cécile Lavoute
- Subjects
0301 basic medicine ,medicine.medical_specialty ,Nitrogen ,Dopamine ,Lipid Bilayers ,Striatum ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Pressure ,medicine ,Animals ,Humans ,Neurotransmitter metabolism ,Nitrogen narcosis ,Chemistry ,GABAA receptor ,Glutamate receptor ,Brain ,medicine.disease ,Corpus Striatum ,Rats ,Receptors, Neurotransmitter ,030104 developmental biology ,Endocrinology ,Inert Gas Narcosis ,nervous system ,Biochemistry ,NMDA receptor ,030217 neurology & neurosurgery ,medicine.drug - Abstract
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). Striatal dopamine levels decrease during exposure to compressed argon, an inert gas more narcotic than nitrogen, or to nitrous oxide, an anesthetic gas. Inversely, striatal dopamine levels increase during exposure to compressed helium, an inert gas with a very low narcotic potency. Exposure to nitrogen at high pressure does not change N-methyl-d-aspartate (NMDA) glutamate receptor activities in Substantia Nigra compacta and striatum but enhances gama amino butyric acidA (GABAA) receptor activities in Substantia Nigra compacta. The decrease in striatal dopamine levels in response to hyperbaric nitrogen exposure is suppressed by recurrent exposure to nitrogen narcosis, and dopamine levels increase after four or five exposures. This change, the lack of improvement of motor disturbances, the desensitization of GABAA receptors on dopamine cells during recurrent exposures and the long-lasting decrease of glutamate coupled with the higher sensitivity of NMDA receptors, suggest a nitrogen toxicity induced by repetitive exposures to narcosis. These differential changes in different neurotransmitter receptors would support the binding protein theory. © 2016 American Physiological Society. Compr Physiol 6:1579-1590, 2016.
- Published
- 2016
38. Measuring Manual Dexterity and Anxiety in Divers Using a Novel Task at 35-41 m.
- Author
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Kneller, Wendy, Higham, Philip, and Hobbs, Malcolm
- Subjects
PUBLISHED reprints ,DIVERS ,MOTOR ability ,INERT gas narcosis ,NITROGEN ,ANXIETY - Abstract
Background: Nitrogen narcosis has a detrimental impact on the manual dexterity of divers and prior research has suggested that this impairment may be magnified by anxiety. Preliminary findings of the effects of depth (i.e., narcosis) and subjective anxiety on a novel test of manual dexterity are presented. Methods: There were 45 subjects who were given a test of manual dexterity once in shallow water (1-10 m/3-33 ft) and once in deep water (35-41 m/115-135 ft). Subjective anxiety was concurrently measured in 33 subjects who were split into `non-anxious' and `anxious' groups for each depth condition. Results: Subjects took significantly longer (seconds) to complete the manual dexterity task in the deep (mean = 52.8; SD = 12.1) water compared to the shallow water (mean = 46.9; SD = 8.4). In addition, anxious subjects took significantly longer to complete the task in the deep water (mean = 48.6; SD = 6.8) compared to non-anxious subjects (mean = 53.2; SD = 9.9), but this was not the case in the shallow water. Discussion: This selective effect of anxiety in deep water was taken as evidence that anxiety may magnify narcotic impairments underwater. It was concluded that the test of manual dexterity was sensitive to the effects of depth and will be a useful tool in future research. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
39. Nitrogen narcosis induced by repetitive hyperbaric nitrogen oxygen mixture exposure impairs long-term cognitive function in newborn mice
- Author
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Bin Peng, Shun-Hua Peng, Run-Ming Qu, Li-Hua Xu, and Zheng-Lin Jiang
- Subjects
Male ,Dendritic spine ,Physiology ,Hippocampus ,Morris water navigation task ,lcsh:Medicine ,Apoptosis ,Open field ,Mice ,0302 clinical medicine ,Cognition ,030202 anesthesiology ,Animal Cells ,Medicine and Health Sciences ,lcsh:Science ,bcl-2-Associated X Protein ,Cognitive Impairment ,Neurons ,Clinical Neurophysiology ,Mammals ,Brain Mapping ,Multidisciplinary ,Behavior, Animal ,Cell Death ,Animal Behavior ,Caspase 3 ,Cognitive Neurology ,Eukaryota ,Brain ,Drugs ,Pascal (unit) ,Electroencephalography ,Electrophysiology ,Bioassays and Physiological Analysis ,Proto-Oncogene Proteins c-bcl-2 ,Neurology ,Brain Electrophysiology ,Cell Processes ,Vertebrates ,medicine.symptom ,Cellular Types ,Anatomy ,Research Article ,medicine.medical_specialty ,Nitrogen ,Imaging Techniques ,Dendritic Spines ,Cognitive Neuroscience ,Amnesia ,Neurophysiology ,Neuroimaging ,Research and Analysis Methods ,Rodents ,03 medical and health sciences ,Cerebellar Cortex ,Internal medicine ,medicine ,Animals ,Pain Management ,Nitrogen narcosis ,Maze Learning ,Anesthetics ,Pharmacology ,Behavior ,business.industry ,lcsh:R ,Electrophysiological Techniques ,Organisms ,Biology and Life Sciences ,Cell Biology ,Neuronal Dendrites ,medicine.disease ,Cortex (botany) ,Mice, Inbred C57BL ,Endocrinology ,Animals, Newborn ,Inert Gas Narcosis ,Cellular Neuroscience ,Amniotes ,Cognitive Science ,lcsh:Q ,Clinical Medicine ,business ,Zoology ,030217 neurology & neurosurgery ,Neuroscience - Abstract
Human beings are exposed to compressed air or a nitrogen-oxygen mixture, they will produce signs and symptoms of nitrogen narcosis such as amnesia or even loss of memory, which may be disappeared once back to the normobaric environment. This study was designed to investigate the effect of nitrogen narcosis induced by repetitive hyperbaric nitrogen-oxygen mixture exposure on long-term cognitive function in newborn mice and the underlying mechanisms. The electroencephalogram frequency was decreased while the amplitude was increased in a pressure-dependent manner during 0.6, 1.2, 1.8 MPa (million pascal) nitrogen-oxygen mixture exposures in adult mice. Nitrogen narcosis in postnatal days 7-9 mice but not in adult mice induced by repetitive hyperbaric exposure prolonged the latency to find the platform and decreased the number of platform-site crossovers during Morris water maze tests, and reduced the time in the center during the open field tests. An increase in the expression of cleaved caspase-3 in the hippocampus and cortex were observed immediately on the first day after hyperbaric exposure, and this lasted for seven days. Additionally, nitrogen narcosis induced loss of the dendritic spines but not of the neurons, which may mainly account for the cognitive dysfunction. Nitrogen narcosis induced long-term cognitive and emotional dysfunction in the postnatal mice but not in the adult mice, which may result from neuronal apoptosis and especially reduction of dendritic spines of neurons.
- Published
- 2017
40. Impairment from Gas Narcosis When Breathing Air and Enriched Air Nitrox Underwater
- Author
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Malcolm B. Hobbs
- Subjects
Adult ,Male ,Nitrox ,Nitrogen ,Diving ,Neuropsychological Tests ,Memory performance ,Young Adult ,Administration, Inhalation ,Humans ,Medicine ,Hypoxia ,Cognitive impairment ,Memory Disorders ,business.industry ,Air ,Public Health, Environmental and Occupational Health ,Middle Aged ,Breathing gas ,Deep water ,Oxygen ,Inert Gas Narcosis ,Anesthesia ,Mental Recall ,Breathing ,Female ,business - Abstract
BACKGROUND Nitrogen (N2) in air causes cognitive impairment from gas narcosis when breathed at increased ambient pressures. This impairment might be reduced by using enriched air nitrox (EANx) mixtures, which have a higher oxygen and lower N2 content compared to air. This study aimed to investigate if divers differed in memory ability and self-assessment when breathing air and EANx30. METHODS The effect of depth (shallow vs. deep) and breathing gas (air vs. EANx30) on memory ability and subjective ratings of impairment was compared in 20 divers. RESULTS Memory performance was significantly worse in deep water (Air: M = 22.1%, SD = 21.7%; EANx30: M = 22.1%, SD = 17.2%) compared to shallow water (Air: M = 29.2%, SD = 18.3%; EANx30: M = 33.3%, SD = 18.2%), but this impairment did not differ significantly between air and EANx30. Subjective ratings of impairment increased significantly from shallow water (Air: M = 5.2, SD = 5.9; EANx30: M = 3.0, SD = 4.4) to deep water (Air: M = 36.8, SD = 25.3; EANx30: M = 24.8, SD = 16.1) when breathing both air and EANx30. However, ratings were significantly lower when breathing EANx30 compared to air when in the deep water. DISCUSSION It was concluded EANx30 does not reduce narcotic impairment over air. Additionally, divers were able to make a correct global self-assessment they were impaired by narcosis, but were unable to make a finer assessment, leading them to erroneously believe that EANx30 was less narcotic than air.
- Published
- 2014
41. Diving under the influence: issues in researching personality and inert gas narcosis
- Author
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Charles H. van Wijk, Jarred H. Martin, and W.A.J. Meintjes
- Subjects
Male ,Nitrogen ,media_common.quotation_subject ,Diving ,Poison control ,Affect (psychology) ,050105 experimental psychology ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,medicine ,Personality ,Humans ,0501 psychology and cognitive sciences ,Big Five personality traits ,Nitrogen narcosis ,Naval Medicine ,media_common ,05 social sciences ,Human factors and ergonomics ,General Medicine ,medicine.disease ,Affect ,Mood ,Inert Gas Narcosis ,Female ,Psychology ,Social psychology ,030217 neurology & neurosurgery ,Cognitive psychology - Abstract
Background: This paper considers the relationship between measures of personality and mood states, and susceptibility to inert gas narcosis. It briefly reviews the topics of inert gas narcosis affecting personality, and personality affecting the susceptibility to inert gas narcosis. There appears to be is a theoretical argument for a possible relationship between measures of personality, mood states, and susceptibility to narcosis. Practically, such a relationship may speak to issues in selection, training and preparation, risk assessments, and even accident investigation in the diving and/or hyperbaric environment. Materials and methods: Twenty one divers completed measures of personality and mood states, and were then compressed to 709 kPa (equivalent to 60 msw) in a dry compression chamber, where they completed a task measuring speed of information processing, and a scale measuring subjective narcosis. Results and Conclusions: The main finding was the absence of any significant correlations between measures of personality traits and mood, and susceptibility to inert gas narcosis. Although the study found no evidence of any major relationship, it is presented as a case study to highlight some of the issues and pitfalls involved in such research. The lessons learned — including the careful defining and describing of concepts, and choosing of samples and measurements — are used to discuss some of the methodological and conceptual issues and future directions for researchers to consider.
- Published
- 2016
42. A Pressurized Nitrogen Counterbalance to Cortical Glutamatergic Pathway Stimulation
- Author
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Jean-Claude Rostain, Nicolas Vallée, and Jean-Jacques Risso
- Subjects
Male ,Baclofen ,medicine.medical_specialty ,Microdialysis ,Nitrogen ,Dopamine ,Glutamine ,Glutamic Acid ,Stimulation ,Striatum ,Biochemistry ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,Glutamatergic ,chemistry.chemical_compound ,Internal medicine ,Basal ganglia ,Pressure ,medicine ,Animals ,Aspartic Acid ,Hyperbaric Oxygenation ,Chemistry ,Glutamate receptor ,Homovanillic Acid ,General Medicine ,Corpus Striatum ,Rats ,Endocrinology ,Inert Gas Narcosis ,Anesthesia ,Saclofen ,3,4-Dihydroxyphenylacetic Acid ,Asparagine ,medicine.drug - Abstract
Previous microdialysis studies performed in rats have revealed a decrease of striatal dopamine and glutamate induced by nitrogen narcosis. We sought to establish the hypothetical role of the glutamatergic corticostriatal pathway because of the glutamate deficiency which occurs in the basal ganglia in this hyperbaric syndrome. Retrodialysis with 1 mM of Saclofen and 100 mM of KCl in the prefrontal cortex under normobaric conditions led to an increase in striatal levels of glutamate by 95.2% and no changes in dopamine levels. Under 3 MPa of nitrogen and with the infusion, the rate of striatal glutamate decreased by 51.3%, to a greater extent than under pressurised nitrogen alone (-23.8%). The rate of dopamine decreased, which also occurred under pressurised nitrogen (-36.9 and -31.4%, respectively). In conclusion, the function of the corticostriatal pathway is affected by nitrogen under pressure. This suggests that the nitrogen-induced break point seems to be located at the glutamatergic striatopetal neurons.
- Published
- 2010
43. Low susceptibility to inert gases and pressure symptoms in TREK-1-deficient mice
- Author
-
Nicolas Vallée, Jean-Claude Rostain, and Jean-Jacques Risso
- Subjects
medicine.medical_specialty ,Nitrogen ,Drug Resistance ,Helium ,Neuroprotection ,Membrane Lipids ,Mice ,Epilepsy ,Potassium Channels, Tandem Pore Domain ,Internal medicine ,Pressure ,medicine ,Animals ,Nitrogen narcosis ,Inert gas ,Mice, Knockout ,Neurons ,Hyperbaric Oxygenation ,Chemistry ,General Neuroscience ,Brain ,medicine.disease ,Immunity, Innate ,Potassium channel ,Atmospheric Pressure ,Endocrinology ,Inert Gas Narcosis ,High Pressure Neurological Syndrome ,Anesthesia ,High-pressure nervous syndrome ,Anesthetics, Inhalation ,Knockout mouse ,Epileptic seizure ,medicine.symptom - Abstract
Nervous disorders may occur after an organism is saturated with inert gases, which may alter the lipid bilayer structure, according to their liposolubility coefficient. Increase in the nitrogen partial pressure induces a neurological syndrome called 'nitrogen narcosis'. By contrast, high pressures of helium induce epilepsy, an high-pressure nervous syndrome symptom. On the basis of an analogy with anaesthetic mechanisms, we used TREK-1 knockout mice, earlier described to volatile the anaesthetics resistance. These mice had a higher threshold of resistance to the narcotic effects of nitrogen and to the death after recurrent epileptic seizure induced by high pressure. TREK-1 channels seem to play a key role in modulating the anaesthetic potential of inert gases and in neuroprotection.
- Published
- 2009
44. Comparison of Nitrogen Narcosis and Helium Pressure Effects on Striatal Amino Acids: A Microdialysis Study in Rats
- Author
-
Nicolas Vallée, Jean-Jacques Risso, Alain Boussuges, and Jean-Claude Rostain
- Subjects
Male ,Microdialysis ,Nitrogen ,Glutamine ,Glutamic Acid ,chemistry.chemical_element ,Helium ,Biochemistry ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Dopamine ,Pressure ,medicine ,Animals ,Asparagine ,Amino Acids ,Nitrogen narcosis ,chemistry.chemical_classification ,Aspartic Acid ,Chromatography ,General Medicine ,Nitrous oxide ,medicine.disease ,Corpus Striatum ,Rats ,Amino acid ,Inert Gas Narcosis ,chemistry ,medicine.drug - Abstract
Exposure to nitrogen-oxygen mixture at high pressure induces narcosis, which can be considered as a first step toward general anaesthesia. Narcotic potencies of inert gases are attributed to their lipid solubility. Nitrogen narcosis induces cognitive and motor disturbances that occur from 0.3 MPa in man and from 1 MPa in rats. Neurochemical studies performed in rats up to 3 MPa have shown that nitrogen pressure decreases striatal dopamine release like argon, another inert gas, or nitrous oxide, an anaesthetic gas. Striatal dopamine release is under glutamatergic and other amino acid neurotransmission regulations. The aim of this work was to study the effects of nitrogen at 3 MPa on striatal amino acid levels and to compare to those of 3 MPa of helium which is not narcotic at this pressure, by using a new technique of microdialysis samples extraction under hyperbaric conditions, in freely moving rats. Amino acids were analysed by HPLC coupled to fluorimetric detection in order to appreciate glutamate, aspartate, glutamine and asparagine levels. Nitrogen-oxygen mixture exposure at 3 MPa decreased glutamate, glutamine and asparagine concentrations. In contrast, with helium-oxygen mixture, glutamate and aspartate levels were increased during the compression phase but not during the stay at maximal pressure. Comparison between nitrogen and helium highlighted the narcotic effects of nitrogen at pressure. As a matter of fact, nitrogen induces a reduction in glutamate and in other amino acids that could partly explain the decrease in striatal dopamine level as well as the motor and cognitive disturbances reported in nitrogen narcosis.
- Published
- 2008
45. Alterations in nigral NMDA and GABAA receptor control of the striatal dopamine level after repetitive exposures to nitrogen narcosis
- Author
-
Michel Weiss, C Lavoute, and Jean-Claude Rostain
- Subjects
Male ,Atmosphere Exposure Chambers ,medicine.medical_specialty ,Nitrogen ,Dopamine ,Glutamic Acid ,Nigrostriatal pathway ,Substantia nigra ,Receptors, N-Methyl-D-Aspartate ,Synaptic Transmission ,Drug Administration Schedule ,GABA Antagonists ,Rats, Sprague-Dawley ,Basal Ganglia Diseases ,Developmental Neuroscience ,Dopaminergic Cell ,Internal medicine ,medicine ,Animals ,GABA-A Receptor Agonists ,GABA-A Receptor Antagonists ,GABA Agonists ,gamma-Aminobutyric Acid ,Neurons ,Air Pressure ,Chemistry ,Pars compacta ,Dopaminergic ,Neural Inhibition ,Receptors, GABA-A ,Corpus Striatum ,Rats ,Substantia Nigra ,Disease Models, Animal ,Endocrinology ,medicine.anatomical_structure ,Inert Gas Narcosis ,nervous system ,Neurology ,Synapses ,Gabazine ,GABAergic ,medicine.drug - Abstract
Nitrogen pressure exposure in rats results in decreased dopamine (DA) release at the striatal terminals of the substantia nigra pars compacta (SNc) dopaminergic neurons, demonstrating the narcotic potency of nitrogen. This effect is attributed to decreased excitatory and increased inhibitory inputs to dopaminergic neurons, involving a change in NMDA and GABA(A) receptor function. We investigated whether repetitive exposures to nitrogen modify the excitatory and inhibitory control of the dopaminergic nigro-striatal pathway. We used voltammetry to measure dopamine levels in freely-moving rats, implanted with dopamine-sensitive electrodes in the striatum. NMDA/GABA(A) receptor agonists (NMDA/muscimol) and antagonists (AP7/gabazine) were administered through a guide-cannula into the SNc, and their effects on striatal dopamine levels were measured under normobaric conditions, before and after five repetitive exposures to 1 MPa nitrogen. NMDA-mediated dopamine release was greater following repetitive exposures, AP7-mediated inhibition of glutamatergic input was blocked, suggesting that NMDA receptor sensitivity was increased and glutamate release reduced. Muscimol did not modify dopamine levels following repetitive exposures, whereas the effect of gabazine was greater after exposures than before. This suggested that interneuronal GABA(A) receptors were desensitized, leading to an increased GABAergic input at dopaminergic cells. Thus, repetitive nitrogen exposure induced persistent changes in glutamatergic and GABAergic control of dopaminergic neurons, resulting in decreased activity of the nigrostriatal pathway.
- Published
- 2008
46. INERT GAS NARCOSIS *
- Author
-
Wallace O. Fenn
- Subjects
Argon ,Atmospheric pressure ,General Neuroscience ,Hyperbaric oxygenation ,Radiochemistry ,chemistry.chemical_element ,medicine.disease ,Nitrogen ,Oxygen ,General Biochemistry, Genetics and Molecular Biology ,History and Philosophy of Science ,chemistry ,medicine ,Inert Gas Narcosis ,Nitrogen narcosis ,Helium - Published
- 2007
47. Moving in extreme environments: inert gas narcosis and underwater activities
- Author
-
James Clark
- Subjects
Nitrogen ,SCUBA ,Physiology ,Diving ,Poison control ,Review ,Decompression sickness ,Aeronautics ,Physiology (medical) ,Medicine ,Orthopedics and Sports Medicine ,Inert gas ,Underwater ,Simulation ,Confusion ,Narcosis ,business.industry ,Extreme environments ,medicine.disease ,Physical performance ,Breathing ,Inert Gas Narcosis ,medicine.symptom ,business ,human activities - Abstract
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. Nitrogen (a major component of air) under pressure can impede mental function and physical performance at depths of as little as 10 m underwater. With increased depth, symptoms can worsen to include confusion, disturbed coordination, lack of concentration, hallucinations and unconsciousness. Narcosis has been shown to contribute directly to up to 6% of deaths in divers and is likely to be indirectly associated with other diving incidents at depth. This article explores inert gas narcosis, the effect on divers’ movement and function underwater and the proposed physiological mechanisms. Also discussed are some of the factors that affect the susceptibility of divers to the condition. In conclusion, understanding the cause of this potentially debilitating problem is important to ensure that safe diving practices continue.
- Published
- 2015
48. Microdialysis study of striatal dopaminergic dysfunctions induced by 3 MPa of nitrogen– and helium–oxygen breathing mixtures in freely moving rats
- Author
-
Michel Weiss, Richard Kinkead, Jean-Claude Rostain, Norbert Balon, Jean-Jacques Risso, and David Dedieu
- Subjects
Male ,medicine.medical_specialty ,Microdialysis ,Nitrogen ,Dopamine ,Movement ,chemistry.chemical_element ,Helium ,Oxygen ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Internal medicine ,medicine ,Extracellular ,Animals ,Nitrogen narcosis ,Molecular Biology ,Chromatography, High Pressure Liquid ,Brain Chemistry ,Air Pressure ,General Neuroscience ,Homovanillic acid ,Dopaminergic ,Homovanillic Acid ,medicine.disease ,Corpus Striatum ,Rats ,Endocrinology ,Inert Gas Narcosis ,chemistry ,High Pressure Neurological Syndrome ,High-pressure nervous syndrome ,Catecholamine ,3,4-Dihydroxyphenylacetic Acid ,Neurology (clinical) ,Developmental Biology ,medicine.drug - Abstract
Previous studies have demonstrated opposite effects of high-pressure helium and nitrogen on extracellular dopamine (DA) levels, which may reflect disturbances on the synthesis, release or metabolic mechanisms. Intrastriatal microdialysis was used to measure the precursor (tyrosine), DA and its metabolites (DOPAC, HVA) levels under nitrogen- or helium- at pressure up to 3 MPa. Under 3 MPa of helium–oxygen breathing mixtures, the extracellular concentration of tyrosine is decreased while the extracellular concentration of DA is increased. On the contrary, nitrogen–oxygen breathing mixture at the same pressure increased extracellular tyrosine concentration and decreased DA release. Under both conditions, an increment of the DOPAC and HVA levels could be noted. Our results suggest that changes in DA release and metabolism during high-pressure helium exposure reflect the effect of the pressure per se, whereas the intrinsic effects of narcotic gases, although sensitive to pressure, would be revealed by hyperbaric nitrogen exposure.
- Published
- 2004
49. Striatal dopamine release and biphasic pattern of locomotor and motor activity under gas narcosis
- Author
-
Michel Weiss, Jean-Claude Rostain, François Blanc, Norbert Balon, and Jean-Jacques Risso
- Subjects
Male ,medicine.medical_specialty ,Light ,Nitrogen ,Narcotic ,Dopamine ,medicine.medical_treatment ,Nitrous Oxide ,Striatum ,Motor Activity ,General Biochemistry, Genetics and Molecular Biology ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Internal medicine ,Electrochemistry ,medicine ,Animals ,Motor activity ,Argon ,General Pharmacology, Toxicology and Pharmaceutics ,Inert gas ,Neurotransmitter ,Electrodes ,Chemistry ,General Medicine ,Nitrous oxide ,Darkness ,Rats ,Neostriatum ,Atmospheric Pressure ,Endocrinology ,Inert Gas Narcosis ,Stereotyped Behavior ,Neuroscience ,medicine.drug - Abstract
Inert gas narcosis is a neurological syndrome appearing when humans or animals are exposed to hyperbaric inert gases (nitrogen, argon) composed by motor and cognitive impairments. Inert gas narcosis induces a decrease of the dopamine release at the striatum level, structure involved in the regulation of the extrapyramidal motricity. We have investigated, in freely moving rats exposed to different narcotic conditions, the relationship between the locomotor and motor activity and the striatal dopamine release, using respectively a computerized device that enables a quantitative analysis of this behavioural disturbance and voltammetry. The use of 3 MPa of nitrogen, 2 MPa of argon and 0.1 MPa of nitrous oxide, revealed after a transient phase of hyperactivity, a lower level of the locomotor and motor activity, in relation with the decrease of the striatal dopamine release. It is concluded that the striatal dopamine decrease could be related to the decrease of the locomotor and motor hyperactivity, but that other(s) neurotransmitter(s) could be primarily involved in the behavioural motor disturbances induced by narcotics. This biphasic effect could be of major importance for future pharmacological investigations, and motor categorization, on the basic mechanisms of inert gas at pressure.
- Published
- 2003
50. Diving medicine
- Author
-
Alfred A. Bove
- Subjects
Pulmonary and Respiratory Medicine ,Nitrogen ,Diving ,Ear, Middle ,Lung Injury ,Critical Care and Intensive Care Medicine ,Decompression Sickness ,Oxygen ,Barotrauma ,Inert Gas Narcosis ,Physical Fitness ,Risk Factors ,Ear, Inner ,Pressure ,Humans - Abstract
Exposure to the undersea environment has unique effects on normal physiology and can result in unique disorders that require an understanding of the effects of pressure and inert gas supersaturation on organ function and knowledge of the appropriate therapies, which can include recompression in a hyperbaric chamber. The effects of Boyle's law result in changes in volume of gas-containing spaces when exposed to the increased pressure underwater. These effects can cause middle ear and sinus injury and lung barotrauma due to lung overexpansion during ascent from depth. Disorders related to diving have unique presentations, and an understanding of the high-pressure environment is needed to properly diagnose and manage these disorders. Breathing compressed air underwater results in increased dissolved inert gas in tissues and organs. On ascent after a diving exposure, the dissolved gas can achieve a supersaturated state and can form gas bubbles in blood and tissues, with resulting tissue and organ damage. Decompression sickness can involve the musculoskeletal system, skin, inner ear, brain, and spinal cord, with characteristic signs and symptoms. Usual therapy is recompression in a hyperbaric chamber following well-established protocols. Many recreational diving candidates seek medical clearance for diving, and healthcare providers must be knowledgeable of the environmental exposure and its effects on physiologic function to properly assess individuals for fitness to dive. This review provides a basis for understanding the diving environment and its accompanying disorders and provides a basis for assessment of fitness for diving.
- Published
- 2014
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