HBO IN COMPLEX TREATING OF ACUTE POISONING.

Practical recommendations.

The tissue metabolism, circulation and external respiration combine a physiologic unity of viability; any change in one of them cause the violations on two other ones. One of the common complications of sharp exogenous poisonings is sharp respiratoric deficiency. Chemical poisonings (CP) can be accompanied with all kinds of hypoxia: hypoxic hypoxia -violations of external respiration (air-blood gaseous exchange); hemic hypoxia - when the properties of hemoglobin are changing; tissue one - histotoxic, the result of violation of tissue

oxidation and circulatoric hypoxia - usual result of poisonings, complicated by exotoxic shock. Restoration of normal supply of tissue with oxygen - that is the principle task of reanimatology. Pathogenetic treating of any kind of hypoxia, caused by poisonings, means the rational application of oxygen. HBO can be of practical use here.

HBO-therapy would be applied in complex with others (specific and symptomatic therapy) and other methods of active detoxification of body (diuresis; hemosorption; dialysis).

Essence and mechanism of HBO.

HBO causes the improvement of concentration of oxygen in liquids of body. That immediately improves the diffusion of oxygen into hypoxic tissue. Handling the pressure of oxygen in environment of patient results in handling of its concentration in tissue.

Respiration causes the deleting of nitrogen from alveolus; its pO2 directly depends only on its value from the beginning and pO2 of gas. Improvement of pO2 in lung causes its tissue tension.

Normal capacity of oxygen is 20,3%, where 20% are terminated to hemoglobin; 0,3% are dissolved in plasma. The improvement of pO2 in lung causes the improvement of dissolved in plasma oxygen; the saturation of this process is practically absent.

pO2 in plasma is directly proportional to pO2 in lung. The improvement of pressure by 1AT causes the dissolving of 2,3 ml of oxygen in 100 ml of blood. The pressure of 3AT of oxygen equates the normal utilization of oxygen via hemoglobin (the difference of arterial and venose blood in oxygen). Oxyhemoglobin practically remains undissociated for absence of need in it. Here is the therapeutic essence of HBO.

Method and practical realization of HBO.

HBO is held in barochamber - that is an isolated vessel with its own gaseous mix, supplied with system of viability. For treating of patients with CP single place chambers "OKA-MG" (with saturation at 1013gPa);  "BL-3" (3039gPa); "Vikkers", "Dregger", "Irtysh" and multiple chambers are applied. The saturation depends on degree of hypoxia and individuality of patient.

Before the procedure the concentration of toxin in tissue; roentgenography of thorax; cardiogram and encephalogram; acid-alkaline balance and gaseous mix in blood are investigated. Paracentosis of tympanic membrane wouldn't be done. The permanent control by means of cardiogram is required. The patients are usually in hard state; sequentially the compression and decompression would be tender and last for 15 - 20 min. The saturation period would last for 40 - 50 min. For each patient the values of procedure would be selected individually as the result of complex investigation of respiration; cardiogram and response of patient.

The necessity of repetitive procedures, if any, is a result of clinical state and dynamics of intoxication.

Application of HBO after acute poisoning by carbon oxide.

The toxicity of carbon oxide (CO) is that it actively interacts with hemoglobin in blood with production of carboxyhemoglobin. This compound is unable to transfer oxygen in tissue; it lessens the amount of oxyhemoglobin (as being synthesed from it); besides all it worthens the ability of remaining oxyhemoglobin to pass the molecules of oxygen in tissue. It also suppresses the hemin enzymes - cytochrom and myoglobin, violating the metabolism directly in tissue. Thus the complex toxicity of CO causes complex hypoxia (hypoxic; tissue and transport one).

The poisoning is displayed if concentration of carboxyhemoglobin is above 20% - this is toxigenic degree of poisoning; if less than 20% - the somagenic one. But this value can't represent the reliable state of patient: time, spent since the intoxication and the activities ofemergent brigades lessen the concentration of carboxyhemoglobin comparatively the degree of disease.

Three degrees of intoxication can be selected:

I. Slight degree - the patient is in conscious all the time. General cerebral violations; little improvement of respiration and pulse index.

II. Medium degree - unconsciousness (for some time; that proves the hard hypoxia); clinically the truncal, pyramidal and extrapyramidal phenomenon arrive.

III. Hard degree (coma; severe violations of respiration and cardiovascular system; trophic skin violations and transgressions of kidney function.

The clinical phenomenon are: at encephalogram - suppression of rhythm and other violations of the general activity; violations of hemodynamics - are improvement of VPM (accompanied by tachicardia) and lessening of OPSS to 800 - 900 din*sm/Sec5. The cardiogram represents hypoxia of myocard and violations of coronar circulation. The investigation of acid-alkaline balance represents compensated alkaloze with unrespiratoric acidose.

The theoretic motivation for application of HBO is the ability to supply tissues with oxygen without the engagement of poisoned with CO erythrocytes. The dissolvement of oxygen in plasma besides improvement of tissue's supply with oxygen, accelerates the bringing out of CO - it improves the partial tension of oxygen and abandons less abilities for the dissolving of CO. The carboxyhemoglobin is being dissociated.

First procedure would be held immediately after arriving of sick; the rest - would depend on the results of investigations. The cardiogram is normalizing usually (because the metabolism in myocard is normalized. The pathological activity at encephalogram also lessens.

pH displays the shift to the alkalization - that also shows the reduction of hypoxia. The patient becomes conscious after the procedure; hypertension lessens; respiration and pulse index are normalizing. In case the II degree of poisoning the saturate pressure would be 1013 - 2529,5 gPa; in case the III degree - improve to 2026 - 2532,5. After 1 hour of procedure the concentration of CO would lessen from 50% to 20; sequentially if the pathology remains unchanged after that, the cerebral inflation and hypoxic violation can be prognosed. In the hardest cases the procedures can be held 4 times a day. In somatic state the effect of HBO is less stable; it mostly depends on the somatic state of organism.

In toxicogeneous state of poisoning HBO is a special kind of therapy, accelerating the withdrawal of CO. In somatogeneous state HBO is a symptomatic therapy, aimed at suppression of hypoxia. The repetitive procedures at that period would be done at 1013 (2026)gPa; the diminishing of hypoxia would be controlled by cardiogram; encephalogram , acid-alkaline balance and psychoneurologic state.

Application of HBO in case the acute poisoning by methemoglobin derivatives.

A vast group of methemoglobines (MB) is a various one. For the best application of HBO the concrete way of synthesis of MB would be taken into account. Two main schemes are existing.

 

1.      Fe2+     +     NO3-     +     H+     à     Fe3+      +     NO2     +     H2O

 

            Fe2+     +     NO2-     +     H+     à      Fe3+     +      N2     +       H2O

 

            Fe2+     +    ClO3-     +     H+     à      Fe3+     +      Cl-     +       H2O

 

Hem transforms to hemin; which cannot be the transporter of oxygen. The compounds of that group can be named the methemoglobinosynthesators of first type. These are:

1)      nitric oxides (NO, NO2);

2)      nitrites (NaNO3), nitrates (KNO3, NaNO3);

3)      nitro- and nitrosoetheres of spirits;

4)      nitrobensol and its derivatives;

5)      chlorates and perchlorates (KClO3, MgClO4).

 

2. The other group derives methemoglobin without changing of valence of metal. The toxicity of such compounds improves because the produced complexes are transferred to the tissues, where the metabolism takes place with founding of severe toxins, influencing liver and kidneys ( aniline, tholuoles, etc.) and hemopoesis (pyrasolones). The toxins of that group are called the methemoglobinosynthesators of complex type. They are: aniline derivatives (aniline, tholuidines, anestisine, etc.); pyrasole derivatives (amidopirine, antipirine, etc.); sulphaniamides.

All of them cause a complex hypoxia: arterial hypoxia from the beginning (after reduction of arterial pO2) later on transforms to hemic hypoxia. In peroral poisonings the primary hemic hypoxia is combined with hypoxia of oxyhemoglobinal genesis (this deals with violations in process of deoxygenation of hemoglobin on tissue capillaries; the utilization of blood worthenes and the shift of pO2 between arterial and venose blood lessens. Poisoning by MB of any kind has some general features: toxic encephalopathies; headache; dizziness; vomity; unconsciousness; convulsions can also take place. The color if skin changes to colors from blue to black. Hypertension and taxicardia are also existing. The concentration of MB can achieve 7 - 73% after poisoning by the methemoglobinosynthesators of complex type; and 7 - 37% after poisoning by the methemoglobinosynthesators of oxygental type.

HBO has a great clinic effect already after the first procedure. When the rest of HBO is persued, only the residues of intoxication and encephalopathia can exist. After 1 - 2 procedures the hyperbaric oxygen, dissolved in plasma finally releases the blood from MB and improves the dissociation of oxyhemoglobin at tissue level.

HBO would be applied in complex with general and specific deintoxical therapy: drinking of water (with later diuresis); inlet of blood in hard cases when 40% and more is MB; alkalization of blood and application of sodium thyosulphate and chromosmone. As CP is accompanied with liver and kidney deficiency the operational detoxification is also indicated (hemosorption; hemodialisis; bougierurage of umbilical vein till the complete deintoxication.

In these cases HBO on the one hand is treating hypoxia, as usual, and on the other - treating the liver and kidney deficiency and anemia (Hyperbaric oxygen is destroying the complexes of MB, violating their hepatic- and nephritic activity.

Application of HBO in treating of poisonings by pfosphorganic insecticides.

The toxic influence of pfosphorganic insecticides (PI) means the violation of nerves system, respiration and cardiovascular system. A complex hypoxia develops with arterial- hemic hypoxia as the principle one.

In PI 3 stages of disease can be determined:

1. excitation (slight intoxication) - at the beginning of disease;

2. hyperkineses and convulsions (medium and hard intoxication) - completely developed disease;

3. convulsions (extremely hard form of disease).

The application of HBO in case the 2 or 3 stage is useless: no bettering can be achieved with often lethality in period from 1 to 4 day (recidive of intoxication accompanied by cardiovascular deficiency and pneumonia).

If a patient is poisoned by carbophos, the HBO is dangerous. This compound makes several transformations before to be withdrawed from the body. One of these intermediate compounds, which can be synthesed only in presence of oxygen, is much more dangerous than the carbophos. Sequentially, the application of HBO, before the carbophos (as well as some other poisons - trichlormetaphos; trolen; nitrophos) is completely withdrawn, is forbidden.

The transformations of chlorophos don't apply hyperbaric oxygen; in that concrete case the HBO isn't contraindicated.

Practically the application of HBO in treating of PI is most advantageous in 20 - 48 hours after the somatogenic stage of poisoning. If the  beginning can't be determined; the HBO wouldn't be applied before 20 hours spent in clinic for patients with II degree, and 48 hours spent in clinic for patients with III degree; later procedures would take place in 10-15 hours one after another. The clinic investigations would perform a steady bettering. Besides therapeutic effect, HBO can be an effective prophylaxis of pneumonia in that period.

As PI is a very hard and severe disease, other kinds of therapy would also be applied: antidotal therapy (atropine, etc.) and intensive detoxicational and symptomatic therapy (hemosorption, hemodialisis).

Application of HBO in treating of poisonings by psychophormatic compounds.

The compounds of that group (barbiturates, bensodiadepines, phenitiasines) narcotically influent the nerves system and violate respiration and cardiovascular system. A complex hypoxia develops with arterial-hypohemic hypoxia of mixed type in the foundation and accompanying of ishemiac hypoxia (hemodynamic hypoxia) of local form.

In clinical practice the poisonings by barbiturates, neiroleptics, tranquilisators or their combinations are usual.

HBO would be applied immediately after the active deintoxicational therapy; it is of secondary application. HBO can be very important if the output from the narcotic coma, caused by hypoxia, is needed. HBO doesn't accelerate the withdrawal of psychophormatic compounds.

Indications and contraindications for application of HBO.

The determination of the stage of the CP (toxicogenic or somatogenic) is of prominent importance for the determination of necessity and probability of application of HBO. HBO can be effective in toxicogenic stage if applied poisons utilizes directly oxygen without synthesizing more toxic compounds. HBO is very effective in somatic therapy at somatogenic stage, when CP is accompanied by general or local hypoxia.

HBO is contraindicated in case the poisoning by compounds, the detoxification of which include the synthesis of intermediate compounds of high toxicity (so-called "lethal synthesis"). The conditional contraindications are: epilepsy; caverns in lung; otorhinolaryngologic diseases; strong hypertension.

 

Professor            E. Luzhnikov,

Doctor         K. Ilyashenko.