Nitrogen poisoning, nitrogen narcosis, deep illness- narcotic effect of nitrogen on the central nervous system (suppression of higher brain functions). It can occur when diving to depths of more than 25 meters with devices with compressed air, depending on the diving conditions (water temperature, fatigue and general physical condition of the diver, excitement, stress, etc.). It can occur at different depths in each person, purely individually. The average depth is 30 meters. The degree of sensitivity to the action of hyperbaric nitrogen is not a constant individual value.
Causes [ | ]
Prevention [ | ]
- Identification of underwater swimmers with increased sensitivity to the toxic effects of nitrogen.
- Limitation of descents in devices in air for persons with hypersensitivity to 40 m and for persons resistant to the toxic effects of nitrogen to 60 m.
- Systematic training under high pressure (1-2 times a month in chambers under high pressure up to 6 kgf/cm²).
- Reduced motor activity when a person is in a hyperbaric environment.
Alexander Sledkov
The great poet Joseph Brodsky wrote in his poem “The New Jules Verne”:
There, under the water, with a dry throat
Life suddenly seems short
Bubbles burst from the mouth.
The equivalent of dawn appears in the eyes.
Counting: one, two, three.
Brodsky believed that water is a reflection of time, the greatest wealth that a person possesses. And indeed, under water, you want to forget about time, like many other things...
Nitrogen narcosis, otherwise called deep intoxication, awaits a diver breathing air or a nitrogen-oxygen mixture (nitrox) at depths of over 60 meters, although individual sensitivity to it is quite wide and many divers begin to feel its symptoms already from a depth of 40 meters.
For the first time, signs of nitrogen narcosis were recorded in 1835 by the Frenchman T. Junot, who noted that when breathing air under high pressure, “brain functions are activated, revitalization, strange lightness occurs, and some people show signs of intoxication.” Following him in 1861, the American J. Green published information about hallucinations, drowsiness and loss of sanity in divers at a depth of 160 feet, and the great French scientist Paul Baire, who is deservedly called the “father of barophysiology,” since he was the first to correctly point out the causes of decompression sickness (decompression sickness) and the toxic effect of compressed oxygen, in experiments on animals in 1878 he discovered the narcotic properties of air under high pressure. Thus, deep intoxication was discovered back in the 19th century. It was then that the first caissons were created for production, in particular, of tunneling and bridge construction work, and caisson workers and divers began to experience the effects of nitrogen and oxygen, compressed to several atmospheres. As an example, we note that graduates of the Kronstadt diving school at the end of the 19th century dived to depths of 50-60 meters.
In the same century, the phenomenon of anesthesia in general was discovered. This name itself comes from the Greek “narke” - “numbness” or “numbness”. It is quite natural that many scientists began to look for an explanation for such a phenomenon caused by ether, nitrous oxide, chloroform and many other chemical compounds. One of the theories of the development of anesthesia, called “lipid”, was put forward by the German Hans Horst Meyer, who suggested that the narcotic strength of a drug depends on its ability to dissolve in fats, i.e. in lipids, and his son Kurt Meyer, having conducted experiments on frogs in a pressure chamber, discovered paralysis in them under a pressure of 90 atmospheres, which disappeared when the pressure was reduced, and in 1923 he called this reversible state “nitrogen narcosis.” Until the mid-1930s. physiologists who studied diseases of divers believed that nitrogen narcosis was caused by the toxic effect of oxygen contained in the air, and not nitrogen, although according to calculations it turned out that the influence of air oxygen should affect approximately 90 meters of depth, in contrast to medical “pure” oxygen , when breathing even depths of about 20 meters become deadly and not a single (!) diver is immune from sudden oxygen poisoning, including convulsions and drowning.
The real causes of nitrogen narcosis were discovered by US Navy Medical Lieutenant Albert Behnke. Beginning in 1935, he published a series of scientific papers showing that the symptoms of the body's reaction to oxygen and nitrogen are different and that when replacing nitrogen in the air with argon, even stronger signs of anesthesia develop. Both nitrogen and argon are highly soluble in fats, and therefore, nitrogen narcosis, like argon narcosis, is caused by the dissolution of gas in the fatty membrane of cells, which is only possible at elevated pressure.
Meanwhile, the divers dived deeper, symptoms of nitrogen narcosis arose more and more often and, at a minimum, significantly complicated the performance of underwater and caisson work. Divers even developed the “law of the dry martini” by correlating the amount of cocktail drunk with the depth of a dive using compressed air. For example, a 300 ml martini corresponded to a descent of 200 feet. In addition, it was noted that people who do not tolerate alcohol well and cannot control themselves after drinking it even in small doses are especially susceptible to deep intoxication.
The invention of scuba gear, which made underwater diving accessible to the public, had, like all other technical advances, a negative side, which consisted in a sharp increase in accidents that occurred under water. The death as a result of nitrogen narcosis of the most experienced French scuba diver Maurice Fargue, a friend of Jacques-Yves Cousteau, who in 1947 signaled from a depth of 300 feet that he was fine, and wrote on a board attached to a cable at a record-breaking at 385 feet, his initials, was unable to ascend on his own. At a depth exceeding 120 m, the effect of nitrogen under a pressure of 12 additional atmospheres on the human brain becomes fatal.
The death of Maurice Fargue was especially senseless also because such depth had long been surpassed in the Soviet Union. In 1932, A.D. Razuvaev dived to 100 m in compressed air, in 1935, I.T. Chertan and V.G. Khmelik - to 115 m, and in 1937, V.I. Medvedev took a soil sample at a depth of 137 m. There is also information that in 1938 - 1939, Soviet divers reached depths of 150-156 meters, breathing air, but this record, like the previous ones, was not officially registered.
During these and other dives, divers experienced hallucinations, agitation, memory and coordination problems, clouding of consciousness and euphoria, which disappeared upon ascent. One of the divers felt like he was in a minefield, another laughed and threw away the tourniquet of his wetsuit, the third wandered aimlessly along the ground, reporting on the phone that he felt great.
In 1933, after the rise of submarine No. 9 from a depth of 84 m, one of the workers of the EPRON (Special Purpose Underwater Expedition) told the writer I. Sokolov-Mikitov: “I felt my head begin to spin, my temples began to pound. circles, circles floated, burst, grew - blue, orange, red. Suddenly I clearly heard music. Clusters of flowers hung before my eyes, lights were running... I was lying on the ground. A comrade took me by the bottom of my shirt with his hands, and us. They started lifting me up together. On the fourth exposure I came to my senses.” And in 1945 - 1946, the authors of the script for the educational film “Physiology and Pathology of Underwater Labor” illustrated the hallucinations caused by nitrogen anesthesia with the image of a frigate rushing towards a diver.
It is impossible not to mention two outstanding Russian physiologists who made a huge contribution to the study of the causes of deep intoxication: Nikolai Vasilyevich Lazarev and Genrikh Lvovich Zaltsman; The author of these lines was lucky enough to work with the latter. In 1939, N.V. Lazarev was the first in the world to induce nitrogen narcosis in a warm-blooded animal (white mouse), which disappeared when the pressure in the pressure chamber decreased. Lazarev believed that “we live in an atmosphere consisting of a strong drug, which does not have a strong effect on us only because it is poorly soluble in water and blood.”
G.L. Zaltsman, conducting experiments with the participation of divers, used electroencephalography and psychophysiological tests. He recorded serious impairments in brain function, as well as handwriting, drawing and associative thinking. Later, in experiments on animals, we were able to objectively prove that at the initial stage of development of nitrogen narcosis, inhibition of the cerebral cortex occurs, as well as the reticular formation - the structure of the central nervous system, which, in particular, ensures the transition of the brain from a sleepy to a wakeful state and vice versa. It should be noted that similar changes occur during alcohol intoxication. However, starting from pressures close to 15 atm, progressively increasing excitation of the subcortex occurs, which can manifest itself as tremors and convulsions. It was also possible to determine which neurochemical substances and ions that carry information in the central nervous system preferentially respond to the effects of increased partial pressures of nitrogen. Finally, pharmacological agents were selected to prevent the development of deep intoxication. True, their uncontrolled use before descent often becomes even more dangerous than the dive itself, which also applies to most other drugs. The fact is that the gases that make up the respiratory mixtures, including oxygen and nitrogen, under elevated pressure begin to act as an additional bioactive reagent that changes the normal state of the body, and against this background, many pharmaceuticals behave completely differently than under normal conditions .
So what does a diver need to know about preventing deep intoxication?
First of all, you need to determine your own sensitivity to nitrogen narcosis. Such tests, carried out in a pressure chamber, are carried out in a number of barocenters in Russia, including the Institute of Medical and Biological Problems (Moscow) and the Military Medical Academy (St. Petersburg). The result of the test will be your personal diving depth on nitrox and compressed air, established by a special physiologist, which absolutely cannot be exceeded.
If you nevertheless ignored this limit and unexpectedly felt signs of an unmotivated euphoric state, exceeding the usual joy from meeting the underwater world, and even more so if you experience visual or auditory hallucinations, immediately surface, of course, observing the rules of decompression. Most likely, these sensations will pass at the next decompression stop.
Remember that even in particularly sensitive people, deep intoxication does not develop at depths of up to 30 meters. But nitrogen narcosis is interdependent with other factors associated with underwater diving. It can be aggravated by low ambient temperatures, and can also lower your body’s temperature; it may increase your sensitivity to decompression sickness, oxygen toxicity, carbon dioxide exposure, etc., and may itself be aggravated by these causes. By taking pharmacological drugs or alcohol before diving, you risk causing a whole chain of interrelated adverse events underwater. We are talking about a drop in body temperature, inappropriate behavior and other reactions of your body, which often result in drowning. A rash decision to make a descent in a state of malaise or even just in a bad mood can lead to an equally disastrous result.
Details about the connection between your diving activity and certain diseases and the use of pharmacological drugs can be found on the pages of the Divers Alert Network magazine; Special physiologists can answer many of your questions. After all, the better prepared you are for the upcoming descent, theoretically and practically, the safer it will be, which is what I sincerely wish for you.
Alexander Sledkov- Doctor of Biological Sciences, Head of the Laboratory of Hyperbaric and Underwater Medicine of the Research Institute of Industrial and Marine Medicine of the Russian Ministry of Health. He has 22 years of experience in the field of hyperbaric physiology. Main scientific works, incl. three monographs are devoted to the study of nitrogen narcosis and high blood pressure nervous syndrome.
After conducting some research, scientists came to the conclusion that at a certain concentration of nitrogen, it tends to act as an intoxicant. Its toxic effect is due to the dissolution of nitrogen cells in fats and metabolic disorders in the human body. Also, deep-seated illness is characterized by a decrease in the speed of attention, a dulling of the sense of self-preservation, and inhibition of thinking.
Why does nitrogen narcosis occur?
The main cause of nitrogen poisoning is the use of an oxygen mixture by divers during a dive, during which a toxic effect on the human brain is observed. Increasing the diving depth by more than 45 meters can cause an attack of euphoria or causeless excitement and panic.
The psychological state of the diver directly affects the course of nitrogen disease. If a person is depressed, then even at the depths of the sea he will experience nothing but anxiety and fear. Very rapid immersion under water causes increased sensations of deep-seated illness, as does cold water or alcohol intoxication.
Features of the disease
Among the many water activities, it is considered one of the most unsafe activities. Lovers of the underwater world can experience a variety of sensations under the influence of the so-called nitrogen - from mild drug intoxication to impaired coordination of movements and even memory loss. Memory problems, inappropriate behavior, gaiety, and hallucinations occur in those divers who dive to a depth of 50-60 m.
Those who decide to exercise in a depressed state, and even dive to a depth of more than 70 m, are characterized by an uncontrollable feeling of fear, panic attacks, prostration, and increased anxiety. The effect of nitrogen on the body is so strong that at great depths (80-100 m) it can cause a narcotic sleep, which can be accompanied by loss of consciousness and even cardiac arrest.
First aid tips and preventive measures
At the first manifestations of deep-seated illness, it is necessary to stop the diver's descent. In most cases, all signs of nitrogen narcosis disappear after raising a person to a depth of about 40 m. If the signs of the disease have not disappeared, it is necessary to lift the victim to the surface and provide him with access to air by freeing him from equipment and restraining clothing.
In order for various types to pass with minimal risk, it is worth following some precautions that will help prevent or alleviate the condition of nitrogen poisoning.
One of the main conditions for prevention is compliance with a certain maximum depth to which divers with different diving experience can descend.
Training descents in pressure chambers will help develop the body's resistance to the effects of nitrogen. This is worth remembering for divers who want to conquer new underwater depths.
In atmospheric air, nitrogen accounts for 78.08 percent. Thus, its partial pressure at sea level is about 0.8 kgf/cm2. Breathing compressed air at depths exceeding 40 m causes nitrogen narcosis (“deep intoxication”).
There are several theories about the nature of anesthesia. Most diving doctors share the theory of Meyer (1899) and Overton (1901), who established that any substance that is chemically inert, but soluble in fats and lipids, is a drug. Moreover, the greater the molecular weight of such substances, the greater the narcotic power of such substances.
Inert gases by molecular weight are arranged in the following order: hydrogen (H2, molecular weight - 2), helium (He - 2), nitrogen (N2 - 14), argon (Ar - 18), krypton (Kr-36), xenon ( Xe - 54). If a person is asked to breathe at atmospheric pressure a mixture containing 21 percent oxygen, in which nitrogen is replaced by xenon or krypton, he will fall into a narcotic sleep.
Nitrogen and argon exhibit narcotic properties as pressure increases.
The first stage of anesthesia is characterized by an imbalance of the processes of excitation and inhibition in the central nervous system, the second - by the predominance of the inhibition process: narcotic sleep develops.
Inhalation of compressed air at depths of 40-50 m reduces the ability for subtle analytical thinking, lengthens the latent time of motor responses, and disrupts complex differentiation. At depths of 50-60 m, a feeling of causeless cheerfulness or depression appears. Sometimes dizziness occurs. The decline in performance is progressing. At depths of 60-70 m, the ability to concentrate weakens, and the diver begins to make mistakes when performing simple professional tasks. The picture resembles alcohol intoxication.
Jacques-Yves Cousteau describes a case of nitrogen narcosis from his underwater research group. Two pairs of scuba divers dived to perform work to a depth of about 70 m. Nearby there was a cliff that went into the depths. When the scuba divers were about to get down to business, one of them suddenly began to plunge into the abyss, not responding to the signals of his comrades. Nitrogen narcosis! The most experienced of the group caught up with him and forcibly pulled him to a safe depth. The victim regained the ability to correctly assess the situation and was very surprised why he was being held by the collar of his diving suit. Subsequently, he could not remember or explain his actions at depth.
Sensitivity to the narcotic effects of nitrogen varies from person to person. Thus, in the above case, only one out of four scuba divers fell into a life-threatening state of drug excitement. In addition, resistance to the narcotic effects of nitrogen increases with repeated dives to depths of 40-60 m.
Due to the possibility of nitrogen narcosis, the rules of the diving service limit diving with compressed air to a depth of 60 m. For diving to great depths, artificial gas mixtures are used with partial or complete replacement of nitrogen with helium. Domestic and foreign studies in recent years have shown that breathing with a helium-oxygen mixture is possible at pressures of the order of 80 atm. and even more.
3 8 ..II. Diseases and injuries associated with changes in the partial pressure of gases
7. Narcotic effects of indifferent gases (nitrogen narcosis) in divers
Diagnostics
7.1. The narcotic effect of indifferent gases (nitrogen narcosis) is a pathological reaction of the body to the effects of increased partial pressures of indifferent gases (in particular, nitrogen) in a gaseous environment or in an inhaled gas mixture and is characterized by changes in higher nervous activity.
The mechanism of narcotic action is based on the saturation of nervous structures with nitrogen, which is manifested by inhibition of higher and disinhibition of lower functions of the brain.
7.2. The reason for the narcotic effect of nitrogen is the excess of the permissible value of its partial pressure in the inhaled gas mixture.
The narcotic effect of nitrogen can be enhanced by the following factors:
Increased or decreased ambient temperature;
Increased content of carbon dioxide or harmful substances (carbon and nitrogen oxides) in the inhaled gas environment;
Hard physical work.
7.3. Nitrogen narcosis in diving practice occurs when compressed air is used for breathing at depths of more than 40 m.
Severe manifestations of nitrogen narcosis may occur
When divers descend in emergency situations to depths of up to 80 m in equipment with an open breathing pattern and in ventilated equipment;
- in equipment with a semi-closed breathing pattern in case of violation of the rules for preparing breathing gas mixtures;
In hyperbaric chambers during training descents and therapeutic recompression under pressure from 6 to 10 kgf/cm 2 (60-100 m of water column).
7.4. Based on clinical signs, three stages of the narcotic effect of nitrogen are distinguished: initial, incomplete anesthesia, and complete anesthesia.
The initial stage develops at increased air pressure of 4-6 kgf/cm 2 (40–60 m water column). It is characterized by a state similar to mild alcoholic intoxication: slight excitement or lethargy, high spirits, decreased self-control, false self-confidence, talkativeness, causeless gaiety.
As a rule, good health and physical performance are maintained.
The stage of incomplete anesthesia occurs at an excess air pressure of 6-10 kgf/cm 2 (60–100 m of water column). At this stage, the above symptoms become more pronounced. Mental performance decreases, orientation in space deteriorates, memory and coordination of movements are impaired. The sense of danger is dulled. It becomes difficult to carry out work, to the point of making it impossible to carry it out. There is a slower reaction to given signals and commands.
Loss of self-control, control of the situation, and control of diving equipment may occur. Rash actions can lead to an emergency.
The stage of complete anesthesia develops when excess air pressure exceeds 10 kgf/cm 2 (100 m of water column). It is characterized by the appearance of visual or auditory hallucinations and loss of consciousness.
During decompression, the effects of the narcotic effect of nitrogen quickly decrease and disappear completely without residual effects in the absence of any therapeutic measures.
7.5. When diagnosing, the magnitude of the partial pressure of nitrogen in the gas environment and the behavior of the diver are taken into account. The effect of nitrogen increases simultaneously with an increase and ceases with a decrease in its partial pressure.
Restoration of the function of higher nervous activity occurs in the reverse order of the onset of symptoms without a pronounced latent period.
First aid when a diver shows signs of the narcotic effect of nitrogen (inappropriate behavior, unreasonable laughter, violation of the rules for using equipment, unreasonable refusal to follow the instructions of the descent leader, etc.) consists of stopping further diving or the diver’s stay on the ground and raising him to the surface (lowering pressure in the pressure chamber) in compliance with the decompression regime.
If a diver loses consciousness under water, one should be guided by the requirements of clause 2.10.2.1 of the Interdisciplinary Rules.
Prevention
7.7. Prevention of nitrogen narcosis in diving practice is achieved by limiting the maximum depth of descent, which for most divers when using compressed air for breathing is 60 m , and for the most experienced divers, if it is necessary to carry out descents in an emergency - 80 m.
