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Narcosis while diving is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gases at high pressure. The Greek word νάρκωσις (narkōsis), "the act of making numb", is derived from νάρκη (narkē), "numbness, torpor", a term used by Homer and Hippocrates. Narcosis produces a state similar to drunkenness, or nitrous oxide inhalation. It can occur during shallow dives, but does not usually become noticeable at depths less than 30 meters (100 ft).
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O
2. Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.
Heliox is a breathing gas mixture of helium (He) and oxygen (O2). It is used as a medical treatment for patients with difficulty breathing because mixture generates less resistance than atmospheric air when passing through the airways of the lungs, and thus requires less effort by a patient to breathe in and out of the lungs. It is also used as a breathing gas diluent for deep ambient pressure diving as it is not narcotic at high pressure, and for its low work of breathing.
In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture.
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraft, submarines, space suits, spacecraft, medical life support and first aid equipment, and anaesthetic machines.
Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs, and eyes. Historically, the central nervous system condition was called the Paul Bert effect, and the pulmonary condition the Lorrain Smith effect, after the researchers who pioneered the discoveries and descriptions in the late 19th century. Oxygen toxicity is a concern for underwater divers, those on high concentrations of supplemental oxygen, and those undergoing hyperbaric oxygen therapy.
In physiology, respiration is the movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction that's to the environment.
Hypercapnia (from the Greek hyper = "above" or "too much" and kapnos = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs. Carbon dioxide may accumulate in any condition that causes hypoventilation, a reduction of alveolar ventilation (the clearance of air from the small sacs of the lung where gas exchange takes place) as well as resulting from inhalation of CO2. Inability of the lungs to clear carbon dioxide, or inhalation of elevated levels of CO2, leads to respiratory acidosis. Eventually the body compensates for the raised acidity by retaining alkali in the kidneys, a process known as "metabolic compensation".
Ladislas Joseph Meduna, a Hungarian neuropathologist and neuropsychiatrist, initiated convulsive treatment, the repeated induction of grand mal seizures in the treatment for psychosis. Observing the high concentration of glia in post-mortem brains of patients with epilepsy and a paucity in those with schizophrenia, he proposed that schizophrenia might be treated by inducing "epileptic" seizures. Thus, chemically induced seizures became the electroconvulsive therapy that is now in worldwide use.
An oxygen bar is an establishment, or part of one, that sells oxygen for recreational use. Individual scents may be added to enhance the experience. The flavors in an oxygen bar come from bubbling oxygen through bottles containing aromatic solutions before it reaches the nostrils: most bars use food-grade particles to produce the scent, but some bars use aroma oils.
Diving disorders, or diving related medical conditions, are conditions associated with underwater diving, and include both conditions unique to underwater diving, and those that also occur during other activities. This second group further divides into conditions caused by exposure to ambient pressures significantly different from surface atmospheric pressure, and a range of conditions caused by general environment and equipment associated with diving activities.
Freediving blackout, breath-hold blackout or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.
Water gas is a kind of fuel gas, a mixture of carbon monoxide and hydrogen. It is produced by "alternately hot blowing a fuel layer [coke] with air and gasifying it with steam". The caloric yield of this is about 10% of a modern syngas plant. Further making this technology unattractive, its precursor coke is expensive, whereas syngas uses cheaper precursor, mainly methane from natural gas.
Argox is the informal name for a scuba diving breathing gas consisting of argon and oxygen. Occasionally the term argonox has been used to mean the same mix. The blend may consist of varying fractions of argon and oxygen, depending on its intended use. The mixture is made with the same gas blending techniques used to make nitrox, except that for argox, the argon is added to the initial pure oxygen partial-fill, instead of air.
Radiation damage is the effect of ionizing radiation on physical objects including non-living structural materials. It can be either detrimental or beneficial for materials.
Breathing is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen.
Hydrogen narcosis is the psychotropic state induced by breathing hydrogen at high pressures. Hydrogen narcosis produces symptoms such as hallucinations, disorientation, and confusion, which are similar to hallucinogenic drugs. It can be experienced by deep-sea divers who dive to 300 m (1,000 ft) below sea level breathing hydrogen mixtures. However, hydrogen has far less narcotic effect than nitrogen and is very rarely used in diving. In tests of the effect of hydrogen narcosis, where divers dived to 500 m (1,600 ft) with a hydrogen–helium–oxygen (hydreliox) mixture containing 49% hydrogen, it was found that while the narcotic effect of hydrogen was detectable, the neurological symptoms of high-pressure nervous syndrome were only moderate.
Work of breathing (WOB) is the energy expended to inhale and exhale a breathing gas. It is usually expressed as work per unit volume, for example, joules/litre, or as a work rate (power), such as joules/min or equivalent units, as it is not particularly useful without a reference to volume or time. It can be calculated in terms of the pulmonary pressure multiplied by the change in pulmonary volume, or in terms of the oxygen consumption attributable to breathing.
Human physiology of underwater diving is the physiological influences of the underwater environment on the human diver, and adaptations to operating underwater, both during breath-hold dives and while breathing at ambient pressure from a suitable breathing gas supply. It, therefore, includes the range of physiological effects generally limited to human ambient pressure divers either freediving or using underwater breathing apparatus. Several factors influence the diver, including immersion, exposure to the water, the limitations of breath-hold endurance, variations in ambient pressure, the effects of breathing gases at raised ambient pressure, effects caused by the use of breathing apparatus, and sensory impairment. All of these may affect diver performance and safety.
References
- ↑ Prisman E, Slessarev M, Azami T, Nayot D, Milosevic M, and Fisher J. (2007). Modified oxygen mask to induce target levels of hyperoxia and hypercarbia during radiotherapy: a more effective alternative to carbogen. International Journal of Radiation Biology. Jul;83(7):457-62.
- ↑ Erowid Carbogen Vault: Basics.
- 1 2 Walsh, Roger N.; Charles S. Grob (2005). Higher Wisdom: Eminent Elders Explore the Continuing Impact of Psychedelics. State University of New York Press. pp. 57–58, 98. ISBN 0-7914-6517-9.
- ↑ Markoff, John (2005). What the Dormouse Said . Penguin. pp. 25, 62. ISBN 0-670-03382-0.
- ↑ Meduna, Ladislas J. (1950). Carbon Dioxide Therapy. Charles C. Thomas Publishing.
- ↑ Arnold JF, Kotas M, Fidler F, Pracht ED, Flentje M, Jakob PM. (2007). Quantitative regional oxygen transfer imaging of the human lung. Journal of Magnetic Resonance Imaging. Aug 8;26(3):637-645
- ↑ "A Multicentre, Randomised, Phase III Clinical Trial Comparing Accelerated Radiotherapy with Accelerated Radiotherapy Plus Carbogen and Nicotinamide (ARCON) in Clinical Stage T2-4 Laryngeal Carcinoma". 6 May 2015.