HYPERBARIC OXYGENATION (grech, hyper-+ baros weight; oxygenium oxygen; synonym: oxybarotherapy, oxygenobarotherapy, giperbaroksiya, giperbarooksigenoterapiya, hyperbaric therapy, oxygen compression) — treatment by oxygen under supertension.
History G. of the lake practically begins from the second half of 20 century though experimental and a wedge, studying of therapeutic effect of compressed air it was widely carried out in 19 century [A. P. Katalinsky, 1862; P. I. Smirnov, 1869; A. I. Simonov, 1876; Junot (V. Th. Junod, 1809 — 1881), Pravats (Ch. G. Pravaz, 1791 — 1853); Bør (P. Bert, 1833 — 1886), etc.], and the first to lay down. the pressure chamber was constructed in England in 1662.
Essence and mechanism of action. Of the lake is the cornerstone increase in partial pressure of oxygen (pO 2 ) in fluid mediums of an organism (plasma, a lymph, an interintercellular lymph, etc.). It leads to the corresponding increase in their oxygen capacity and is followed by increase in diffusion of oxygen to hypoxemic sites of fabrics. Regulating pressure of oxygen in the inhaled gas mixture and consequently, and in alveoluses, it is possible is dosed to increase its concentration in internal environments of an organism.
Breath by oxygen leads to removal of nitrogen from alveoluses, and alveolar pO 2 at the same time depends only on the size pO 2 in the inhaled mix, and also from the pCO level 2 and rh2o in alveoluses (these are more or less stable sizes, they practically do not change at change of surrounding pressure). Increase in pressure of the inhaled oxygen to 2, 3, 4 at and more causes raising of alveolar pO 2 to 1433, 2193, 2953 mm of mercury. and more (at breath by pure oxygen alveolar pO 2 — 673 mm of mercury., at breath by air under atmospheric pressure — 100 mm of mercury.).
Increase in pO 2 in lungs in turn leads to increase of tension of oxygen in an arterial blood: to 1100 — 1400 mm of mercury. at 3 at (initial arterial pO 2 90 — 95 mm of mercury.).
Normal the oxygen capacity of blood on average makes 20,3 about. %, from which 20 about. by % of oxygen it is connected with hemoglobin, and 0,3 about. % are dissolved in plasma. Under natural conditions the oxygen dissolved in plasma in a quantitative sense has no great power value, and life activity of an organism is provided with the oxygen transferred by hemoglobin. Increase of alveolar pO 2 causes increase in arterial pO 2 also leads to sharp increase in amount of the oxygen dissolved in plasma. Rise it happens in proportion to increase in pressure in a pressure chamber and is practically not limited.
Amount of the oxygen dissolved in a blood plasma, in direct ratio pO 2 in alveoluses. Build-up of pressure of the inhaled oxygen on 1 at involves additional dissolution in 100 ml of blood apprx. 2,3 ml of oxygen. Thereof breath by oxygen under pressure of 3 at leads to additional dissolution in blood about 6 about. % of oxygen that corresponds to normal oxygen consumption by an organism at rest — its arteriovenous difference on oxygen. Oxyhemoglobin at the same time practically does not dissociate since even without participation of hemoglobin the oxygen capacity of blood is quite sufficient for maintenance of life here (a phenomenon «life without blood»). Therefore with a pressure of oxygen of 3 at the majority of fabrics (the exception represents only a myocardium) entirely will satisfy the oxygen requirement only at the expense of its physically dissolved fraction. The therapeutic value of G. of the lake is also based on it.
Ability to considerably increase the oxygen capacity of blood allows to use G. of the lake at patol, states when hemoglobin is in whole or in part excluded from process of breath, i.e. at anemic (massive blood loss) and toxic (poisonings with education carboxy - met-and sulfhemoglobin) forms acute gemichesky hypoxias (see), and also for compensation of metabolic needs of an organism for oxygen at decrease in volume of the circulating blood and speed of a blood-groove.
Increase in tension of oxygen in an arterial blood does not lead to strictly linear raising of pO 2 in fabrics and cells. Extent of its increase in various bodies depends on vascularization, conditions of a local blood-groove, oxygen capacity of fabrics, intensity of metabolism, etc.
Increasing the oxygen capacity of fluid mediums of an organism, the lake at the same time creates to G. also certain conditions for deposition of oxygen in fabrics. Under G.'s cover by the lake therefore perhaps longer switching off of blood supply head and back * a brain that forms the basis for use of this method in kardio-and neurosurgery.
At assessment of reaction of an organism to supertension of oxygen it is necessary to distinguish the changes arising under the influence of dotoksichesky doses of oxygen (compensatory and adaptive reactions) and the shifts testimonial of its toxic action arising at overdose of oxygen (see. Hyperoxia ).
At influence of the therapeutic regime G. of the island the natural change of a number of the vital functions of an organism directed to restriction of excessive increase in pO is observed 2 in fabrics: breath urezhatsya and goes deep, bradycardia is noted, cordial emission and an organ blood stream decrease, peripheric vascular resistance increases etc. The irritation of the parasympathetic centers arising at adaptation to a hyperoxia is the cornerstone of the majority of these phenomena.
Fiziol, reaction of an organism to increase in pO 2 usually proceeds in a certain sequence (scheme). Increase in arterial pO 2 leads to elimination of normal hypoxemic activity of peripheral chemoceptors, decrease in excitability of a respiratory center and oppression of lung ventilation. The last is followed by increase in arterial pCO 2 the brain causing expansion of blood vessels. At the same time increase of tension of oxygen in blood causes disturbance of dissociation of oxyhemoglobin (level of the recovered hemoglobin in a venous blood decreases), increases acidity of blood, complicates transport of carbon dioxide gas and hydrogen ions in tissues of a brain, including a respiratory center. Hypercapnia (see) leads, in turn, to increase in minute volume of breath and a hyperventilation. As a result of pCO 2 in an arterial blood falls, vessels of a brain are narrowed and tension of oxygen in tissues of a brain decreases.
G.'s kind of the lake is therapy by compressed air. At a number of forms of respiratory insufficiency 'compressed air can be more effective, than pure oxygen. The hypercapnia at the same time usually does not accrue, and presence of nitrogen at alveoluses to some extent prevents (or stops) oxygen injury of lungs, in particular development of atelectases.
G.'s Use by the lake in clinic is shown almost at all expressed cases acute and hr. oxygen insufficiency. And lakes (sometimes in combination with a hypothermia and pharmakol, drugs) apply G. not only to fight against already developing hypoxia, but also to its prevention. Besides, oxygen under supertension in some cases possesses antimicrobic action (anaerobic and some aerobic bacteria). For its manifestation fabric pO 2 shall exceed considerably datum level, i.e. for this purpose it is necessary to achieve considerable hyper oxygenation of fabrics.
Lech. action of a hyperoxia can be caused not only by elimination of a fabric hypoxia, but also direct influence of the increased tension of oxygen on these or those structures of an organism. In particular, vasoconstrictive effect of oxygen on cerebral vessels is used for fight against wet brain, one of elements of a pathogeny to-rogo the vazodilatation and disturbance of permeability of a vascular wall is.
At some types of pathology of G. of the lake plays a supporting role, but despite it it quite often defines success of treatment. Potentiation by a hyperoxia of anti-blastic effect of the alkylating drugs can be an example; G.'s use by the lake in a complex with radiation therapy for strengthening of radio sensitivity of malignant tumors; at extracorporal blood circulation where oxygen at the same time increases efficiency and safety of a method.
A specific place is held by G. the lake in a complex of an intensive care. Oxygen under supertension is widely used for normalization of sharply broken functions of vitals. The acute heart failure, ischemic heart diseases, a brain, kidneys, a liver, soft tissues of extremities, some forms of shock serve as the direct indication for G.'s carrying out of the lake.
In the conditions of respiratory insufficiency of G. of the lake it is applied at the resistant arterial anoxemia caused by disturbance of the relation of ventilation to a blood-groove. However at the expressed ventilating insufficiency of G. of the lake can be effective only when full ventilation of the lungs is provided.
Of the lake is the only method of normalization of partial pressure and the oxygen content in an arterial blood at considerable impurity in it a venous blood (the veno-arterial shunt at inborn heart diseases etc.).
The technique and technology of use
Therapeutic regime G. of the island in most cases consists of pressure 2 — 3 at on exposure of 1 — 2 hour. Respect for the specified norms allows not only maximum to lay down. the effect, but also practically excludes development of the expressed forms of oxygen intoxication.
Of the lake is carried out in to a pressure chamber (see), i.e. the vessel which is hermetically isolating the gaseous fluid concluded in it from the surrounding atmosphere and supplied with a life support system, and also the device on prevention and accident elimination.
The design to lay down. pressures chamber it is to some extent caused by its purpose. There are two main types of cameras for G. of the lake — single and many-placed to lay down. pressures chamber at in the last, except one or several patients, there are service personnel. Besides, there are pressures chamber for banking, and also pressures chamber of various designs for the experimental purposes.
One - and many-placed cameras essentially differ: on structure of a gaseous fluid (in single usually — oxygen, in many-placed — air or other respiratory mixes), to design features, equipment, operation etc.
Working pressure in single pressures chamber to 3 — 4 at. The patient directly breathes the gaseous fluid (oxygen) creating pressure. Therefore there is no need to surely use the respiratory equipment, and to lay down. the effect in some cases, napr, at the patients having wounds and ulcers owing to direct effect of oxygen on a wound surface increases.
To destination single pressures chamber are divided into cameras for adult (fig. 1), newborns and children up to one year, and also for radiation therapy of oncological patients.
Distinguish mobile (established in ambulance cars), figurative (used in field conditions) and stationary single pressures chamber. The last place in standard hospital buildings, their installation and operation are simple, the number of service personnel is small.
Many-placed pressures chamber on volume not less than 3000 l with working pressure up to 10 kgfs/cm2. They consist of two or more compartments, one of which plays a role of a lock and can be used for an entrance and escaping of the camera during G.'s session of the lake and during the carrying out rescue operations. A gaseous fluid of a many-placed pressure chamber, as a rule, is air (breathing oxygen of patients is brought independently through a mask or an endotracheal tube).
Equipment many-placed to lay down. pressures chamber depends on their appointment. In therapeutic cameras where the intensive care and resuscitation is carried out, the equipment for artificial ventilation of the lungs, a hypothermia etc. is installed.
The pressure chamber operating room consists of two compartments preoperative and operational. The first serves as a lock, for an entrance to the operating room at supertension, for placement of necessary surgical tools and the control instrumentation. Unlike pressures chamber of other appointment, in a pressure chamber operating room big requirements are imposed to sterility of air, frequency rate of ventilation. In a pressure chamber there is an operating table (with the hydraulic lift device filled with solution of glycerin), the narcotic device and the medical ventilator, the cardiopulmonary bypass etc. The operating lamp shall be in explosion-proof execution.
Considering the high partial pressure of oxygen, a zatrudnennost of bystry evacuation of people from a pressure chamber in case of fire, it is necessary to pay special attention to the accident prevention. All equipment for functional researches (the electrocardiograph, the electroencephalograph) and other necessary devices (e.g., a defibrillator, an electroknife) are placed out of a pressure chamber. In a pressure chamber there are only electrodes and sensors which join the special guard connected by a cable through germorazjy to the specified equipment. Considering that all elements of a pressure chamber are made of metal, special requirements are imposed to isolation of electric inputs in a pressure chamber.
The use in a pressure chamber of combustible substances, the materials accumulating static electricity is forbidden. In a pressure chamber it is impossible to apply explosive anesthetics — ether, cyclopropane, etc. Fire-prevention devices — «rain» installation and water fire engines shall be provided in it.
At observance of all safety regulationss the pressure chamber operating room can be used practically at all types of surgical interventions.
Except separate many-placed a pressure chamber in some cases the so-called barokompleks consisting of several big cameras of different function connected among themselves Are created.
The world's largest barokompleks is the Center of hyperbaric oxygenation All-Union research in-that clinical and experimental surgery, the total amount of cameras to-rogo makes 270 m 3 . The complex turns on 6 cameras connected among themselves which are divided into three blocks: operational therapeutic and research (fig. 2). The surgical block consists of laboratory and operational cameras (fig. 3). Therapeutic — from the therapeutic camera (fig. 4) and an angular lock. The research block — from the research camera with a lock. Sizes of the therapeutic camera (70 m 3 ) 4 lying or 8 sedentary patients and 2 — 3 people of service personnel allow to place in it. In the surgical camera (70 m 3 ) there can be a crew from 8 — 10 persons.
Successful use of G. of the lake depends on the choice optimum to lay down. the modes, training of service personnel in work in the camera, the organization of system of maintenance and creation of the corresponding baroapparatura, and also from safety of the patient and personnel working under pressure.
At long effect of oxygen develop the dekompensatorny reactions which are shown functional and structural disturbance in various systems and bodies.
Frequency of oxygen poisoning at G. of the lake is rather small: according to the all-Union questionnaire (1975) covering more than 6800 sessions it met in only 0,07% of cases. It is accepted to allocate two main forms of oxygen intoxication — acute and chronic (subacute). Acute poisoning arises on short-term exposure of rather high pressures of oxygen (3 at above). To defeat it is most subject to c. N of page therefore this form is designated as neurotoxic or convulsive.
Symptoms of oxygen intoxication appear through a certain period. Duration of this stage of latency is extremely variable and subject to influence of many factors. First of all treat them: individual sensitivity to oxygen, temperature and humidity of the environment, concentration of carbon dioxide gas in the inhaled gas, emotional and physical. loadings, condition of c. N of page, initial oxygen mode of an organism and so forth.
Initial toxic effect of oxygen on a cell, apparently, is connected with an ingibition of respiratory enzymes and with accumulation of peroxides of the lipids causing damage of cellular structures. The most sensitive to oxygen were fermental systems of SH group. Excessive increase in pO 2 in a cell leads to change of metabolism in a cycle of Tricarboxylic acids, to disturbance of synthesis of high-energy phosphatic connections and to education of free radicals.
The most precursory objective symptoms of the developing acute oxygen intoxication consider changes of EEG (emergence of the resistant and multiple centers of convulsive activity) and an ECG (change of a voltage of teeth and cordial conductivity), and also increase of pulse and breath. The preconvulsive stage of acute oxygen poisoning is shown by vegetative disturbances (tachycardia, nausea, the dizziness, a vision disorder, paresthesias complicated and hurried breathing etc.) and local muscular twitchings (especially in the field of a century, lips, a forehead). Then there are generalized tonic and clonic spasms proceeding as classical epilepsy.
At the first signs of oxygen poisoning it is necessary to make a decompression and to switch the victim to breath by air. Any other specific means for fight against acute oxygen intoxication do not exist. When it is possible, a transfer of the victim into breath by air shall be made even before pressure decrease.
Hron, oxygen intoxication is possible at long, sometimes repeated, influence of small pressure of oxygen. At the same time changes of lungs — a pulmonary form of intoxication are leading.
The first signs hron, oxygen intoxication are, as a rule, connected with irritant action of oxygen on upper respiratory tracts: a hyperemia, swelling of a mucous membrane, burning, dryness in a mouth and other unpleasant feelings. Further join them a tracheobronchitis (pain behind a breast, dry cough, hurried breathing, rise in temperature) and pneumonia. Radiological strengthening of the pulmonary drawing, atelectases is noted (the last consider a pathognomonic sign of this form of intoxication). At timely cancellation of oxygen of any effects neither that, nor other form of intoxication leaves.
== There is no contraindication == Absolute contraindications to G. of the lake. Relative contraindications: disturbance of passability of the acoustical (eustachian) pipes and channels connecting okolonosovy bosoms to the environment (polyps, inflammatory processes on average an ear, adnexal nasal cavities, nasopharynxes, different anomalies of development etc.); existence of the closed gassy cavities in a lung (cavities, abscesses, cysts) both other fabrics and bodies; all diseases proceeding with paroxysms of cough; epilepsy or any other convulsive attacks in the anamnesis; severe forms of hypertensia; some diseases of lungs which are followed by obturation of bronchial tubes and disturbance of ventilation; hypersensitivity to oxygen; claustrophobia. With care it is necessary to treat G.'s carrying out of the lake at patients of senile age, at patients with high fever and at severe damages of a retina of an eye, at patients with a pneumosclerosis, at the endocrine diseases which are followed by the strengthened allocation of corticosteroids, catecholamines, thyroid hormones.
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B. V. Petrovsky, C.H. Efuni.