Major Clinical Syndromes. Anaphylactic shock is a symptom complex of acute grave general allergic reactions of immediate type

Anaphylactic Shock

Anaphylactic shock is a symptom complex of acute grave general allergic reactions of immediate type, characterized mainly by the initial stimulation and subsequent inhibition of the function of the central ner­vous system, bronchospasm, and a marked arterial hypotension.

Aetiology. An anaphylactic shock may be caused by repeated intake of substances which sensitize the body when taken for the first time. Usually these are medicinal preparations such as penicillin, streptomycin, procaine, vitamin Bj, some other antibiotics, sulpha drugs, vaccines, sera, extracts of pollen of some plants, etc. It is important to note that an anaphylactic shock may develop after administration of small doses of the preparation which was given earlier in larger doses, e.g. in intracutaneous injection of-only a few units of penicillin (in diagnostic test for allergy). An anaphylac­tic shock may develop from using a syringe which was sterilized together with syringes and needles that were used to inject penicillin to other pa­tients. Inquiry of patients predisposed to anaphylactic shock can often reveal allergic reactions in the past history. An anaphylactic shock usually

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Special Part

Chapter 11. Diseases of Bones, Muscles, Connective Tissue

arises in parenteral administration of medicines but it can also develop when these substances contact the mucosa. In some cases, an anaphylactic shock may occur from insect bites.

Pathogenesis. The pathogenesis of anaphylactic shock consists in sen-sitization of the body during the first intake of the antigen (medicinal substance, vaccine, etc.) and production of antibodies, which are partly fixed on various tissue cells. On repeated intake of the same substance, a reaction occurs by which an antigen-antibody complex is produced. Biologically potent substances, such as histamine, bradykinin, serotonin, etc., are released immediately from the cells into the blood in large quan­tities. These substances produce various effects on the organs and systems of the body to cause spasms of smooth muscles and to increase vascular permeability, while combination of the antigen with the circulating an­tibodies activates the complement and causes formation of anaphylatoxin. In atopy (hereditary allergy characterized by congenital presence of an­tibodies to certain allergens), an anaphylactic shock may develop during the first contact with this substance.

Clinical picture. In addition to the described general symptoms, anaphylactic shock may have some specific features. Anaphylactic shock develops rapidly, in a few seconds or minutes (to 30 minutes), following the intake of the allergen. The first symptoms are usually vertigo, headache, fear, cold sweat, dyspnoea, anxiety, pressure in the chest, and paroxysm of cough. In some cases, skin itching develops simultaneously. Some patients develop allergic urticaria, allergic oedema, tachycardia, abdominal pain, vomiting, diarrhoea, and often convulsions. The further picture varies: rapidly developing oedema of the throat and asphyxia, progressive hypotony, oedema and haemorrhages into the internal organs (which are especially dangerous if they affect the brain). In grave cases, the patient soon loses consciousness; this is an unfavourable prognostic sign.

Despite the varied clinical picture of anaphylactic shock, its diagnosis is not difficult: the main sign is the rapid response of the patient to the ad­ministration of the medicine. The shock may occur immediately. A routine systemic examination of the patient is impossible and urgent measures should be taken to recover the patient from the shock. This done, the physician may proceed with verification of the diagnosis.

Prognosis. The prognosis is serious in all cases: the patient may die within the first minutes or hours of asphyxia, cardiovascular insufficiency, or irreversible affections of the vitally important organs. The latter may develop and become the cause of death at later terms (in several days). After the patient has been drawn from the critical state, he should be given a thorough medical observation and examination by laboratory and in-

strumental methods (as indicated). This enables the physician to diagnose the affection of this or that organ at the early stage of the process.

Treatment. It is necessary to stop the allergic effect, e.g. to apply a tourniquet to the extremity into which the medicine was injected or which was bitten by an insect. This should be followed by administration of adrenaline (as a vasoconstrictive agent) to arrest the allergen supply from the tissues into the blood. Antihistamine preparations (dimedrol, suprastin, etc.), glucocorticosteroids and their analogues (prednisolone, etc.), having pronounced anti-allergic and anti-inflammatory action, should also be given. Depending on the special character of each particular case, symptomatic treatment should be given: oxygen therapy, cardiac glycosides, angiotonics, etc.

Prophylaxis. A thoroughly collected allergic anamnesis is very impor­tant. The patient should be asked to what preparations he might have allergic response, or if he has atopy or hereditary predisposition to allergic reactions. If this information is available, the physician should exclude those preparations to which the patient has the allergic reaction. Any room, where patients are given injections of medicinal preparations, should be equipped with all necessary means to recover patients from possible anaphylactic shock.

Allergic Oedema

Allergic oedema (angioneurotic oedema, Quincke's oedema) is characterized by attacks of transient circumscribed oedema of the skin, subcutaneous connective tissue, and mucosa.

Aetiology and pathogenesis. This is an allergic reaction to various allergens. Vascular reactions, and in the first instance increased vascular permeability, are important factors causing allergic oedema.

Clinical symptoms. The angioneurotic oedema develops acutely, a few seconds or minutes following the intake of the allergen (usually without any precursors). As a rule, oedema affects the lip, the cheek, the eye, but it can also develop in any organ (oedema of the throat, stomach, etc.). The oedema persists from a few minutes to several hours. The size of the swollen area varies, but it rarely exceeds the size of the palm. The allergic oedema may recur, not infrequently on the same organ.

Treatment. Intravenous infusions of a 10 per cent calcium gluconate solution, administration of antihistaminic preparations, glucocor­ticosteroids (prednisolone, etc.). Symptomatic therapy is also recommend­ed (e.g. in oedema of the laryngeal mucosa).

Prophylaxis. Medicines or foods which are known to cause the allergic reactions should be excluded.

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