Anaphylactic shock

Introduction to anaphylactic shock Anaphylactic shock is an acute systemic reaction in the body that is allergic to certain biological products (such as allogeneic serum) or drugs (such as penicillin, iodine-containing contrast agents). It is due to vasomotor dysfunction caused by histamine, serotonin and other vasoactive substances released in the immediate antibody-antibody reaction, increased permeability of blood vessel wall, extravasation of blood plasma, sudden decrease in blood volume, and insufficient tissue perfusion. Cause shock, often accompanied by laryngeal edema, tracheal spasm, pulmonary edema. Mainly manifested as itchy skin, urticaria; difficulty breathing, chest tightness, cough; abdominal pain, nausea, vomiting; dizziness, pale, severe cases quickly into shock state. If you do not rescue in time, you can often die within 5-10 minutes. basic knowledge The proportion of illness: 0.001% Susceptible people: people with allergies Mode of infection: non-infectious Complications: disturbance of consciousness nausea and vomiting edema

Causes of anaphylactic shock

Biological factors (35%):

Endothelin (insulin, vasopressin), enzyme (chymotrypsin, penicillinase), pollen infusion (porcine grass, tree, grass), food (egg, milk, hard fruit, seafood, chocolate), antiserum ( Anti-lymphocyte serum or anti-lymphocyte gamma globulin), occupational exposure to proteins (rubber products), bee toxins.

Drugs (30%):

Examples include antibiotics (penicillin, cephalosporin, amphotericin B, nitropyrazine), local anesthetics (procaine, lidocaine), vitamins (thiamine, folic acid), diagnostic preparations (iodine) X-ray contrast agent, iodonium bromide), occupational exposure to chemicals (ethylene oxide).

The vast majority of anaphylactic shock is a typical type I allergy in the body of multiple organs, especially the performance of the circulatory system, the external antigenic substance (some drugs are not whole antigen, but after entering the human body, combined with protein into a whole antigen) The body can stimulate the immune system to produce corresponding antibodies, in which the yield of IgE varies greatly depending on the constitution. These specific IgEs have strong pro-cell properties and can be associated with "target cells" such as skin, bronchi, and blood vessel walls. Binding, when the same antigen is again contacted with the sensitized individual, it can trigger a wide range of allergic type I allergic reactions, and various histamine, platelet activating factor, etc. released during the process cause multiple organ edema, exudation The direct cause of clinical manifestations.

In the process of blood transfusion, plasma or immunoglobulin, immediate anaphylactic shock can also be seen, and their causes are three: 1 The specific IgE of the donor is reacted with the drug being treated by the recipient (such as penicillin G). 2) Selective IgA deficiency can produce anti-IgA IgG antibody after multiple infusions containing IgA blood products. When IgA-containing products are re-injected, IgA-anti-IgA antibody immune complex may occur, type III occurs. Allergic shock caused by allergic reaction; 3 gamma globulin (gamma sphere) preparation for intravenous infusion contains high molecular weight propylene globule polymer, which can activate complement and produce anaphylatoxins such as C3a, C4a, C5a; Cells that produce anaphylactic shock, a small number of patients after the application of drugs such as opium sputum, dextran, high-eluting X-ray contrast agents or antibiotics (such as polymyxin B), mainly through the degranulation of mast cells, will also The clinical manifestations of anaphylactic shock, late, people will not have allergens and antibodies, that is, the symptoms and signs of anaphylactic shock through non-immune mechanisms are called allergic reactions (Anaphylactoid reaction).

Pathological change

The main pathological manifestations of sudden death due to this disease are: acute pulmonary blood stasis and hyperinflation, laryngeal edema, visceral hyperemia, pulmonary interstitial edema and hemorrhage, microscopic edema of airway submucosa, increased airway secretions, bronchi and Pulmonary interstitial vascular congestion with eosinophil infiltration, about 80% of death cases with myocardial focal necrosis or lesions, spleen, liver and mesenteric vessels are also hyperemia with eosinophil infiltration, a few cases can also have digestion Road bleeding and so on.

Anaphylactic shock prevention

Prevention of the most fundamental methods to clear the allergens of this disease, and effective prevention and prevention, but it is often difficult to make specific allergen diagnosis in clinical, and many patients belong to allergic reactions that are not caused by immune mechanisms, Pay attention to this:

1. Consult the history of allergies before using the drug. Positive patients should make a striking and detailed record on the front page of the medical history.

2, try to reduce the need to take medicine, try to use oral preparations.

3, for patients with allergies after the injection of drugs for 15 to 20 minutes, before you must receive the drug that induces the disease (such as sulfonate contrast agent), it is best to use antihistamines or prednisone 20 ~ 30mg.

4, the first skin test in the skin test, try not to have a positive drug, if it must be used, you can try the "desensitization test" or "desensitization test", the principle is that under the protection of antihistamines and other drugs, The patient gradually increases the amount of the desensitized drug from a very small dose until the patient develops tolerance. During the desensitization process, there must be close observation by the medical staff, and the aqueous adrenaline, oxygen, endotracheal intubation and preparation are prepared. All emergency rescue measures such as intravenous corticosteroids.

Anaphylactic shock complications Complications, dysfunction, nausea and vomiting edema

The most serious complication of the disease is death.

Symptoms of anaphylactic shock Common symptoms Ambiguous consciousness disorder Skin itching syncope Skin pale wheal skin Itching scratches Hypotension Lips pale palpitation

1. The blood pressure drops sharply to the level of shock, which is 10.7/6.7 kPa (80/50 mm Hg). If the patient has hypertension, the systolic blood pressure drops to 10.7 kPa at the original level. Mm Hg) can also be considered to have entered a state of shock.

2, the state of consciousness begins to have fear, palpitation, irritability, dizziness or shouting, and can appear amblyopia, yellow vision, illusion, double vision, etc.; then consciousness, even consciousness is completely lost, light reflection and other reflections weaken Loss of death.

Have a blood pressure drop and disturbance of consciousness, can be called shock, both are indispensable, if only shock performance. Not enough to indicate that it is anaphylactic shock.

3, allergic prodromal symptoms: including skin flushing or transient skin pale, chills, etc.; skin itchy or palm itching, skin and mucous membrane numbness, mostly for lips and limbs, followed by a variety of rashes Most of them are windy lumps. In severe cases, there are large subcutaneous vascular edema or swollen body skin. In addition, edema can occur in the nose, sputum, and throat mucosa, and sneezing, clear watery nose, dumb sound, and difficulty breathing , throat, etc., many patients have esophageal obstruction, abdominal discomfort, accompanied by nausea, vomiting and so on.

4, allergen exposure history: before the emergence of shock medication, especially the history of drug injection, and other specific allergen exposure history, including food, attracting people, contact objects, insect spurs and so on.

Anaphylactic shock test

1, arterial pressure measurement: blood pressure decreased.

2. Measurement of central venous pressure (CVP): CVP decreased.

3, lung hair pressure (PCWP) measurement: rapid decline.

4, urine volume measurement: reduced urine output, and even no urine.

5. Determination of cardiac output (CO) and cardiac index (CI).

6, ECG monitoring.

7, arterial blood gas analysis.

8, red blood cell count, hemoglobin and hematocrit determination.

Diagnosis of anaphylactic shock

Diagnose based on

1. Have a history of allergen exposure.

2, dizziness, pale, difficulty breathing, chest tightness, cough.

3, abdominal pain, nausea, vomiting.

4, pulse speed, blood pressure drops.

For general anaphylactic shock, the above four points can be diagnosed, anaphylactic shock sometimes occurs extremely rapidly, sometimes lightning-like, so that the symptoms of allergies are not obvious, as for the specific cause of anaphylactic shock diagnosis should be cautious Trial, because when a patient has a shock, often using multiple drugs or exposure to a variety of suspicious sensitizing substances, it is difficult to determine; in addition, during the allergy test such as drugs for confirming diagnosis, false If the positive result or re-shock is serious, it should be cautious. If it is necessary, it should be safe. If it is highly sensitizing substance or the patient is highly sensitive to its sensitizing substance, it should be done by patch, scratch and other tests. Or, using the conjunctival test, sublingual mucosa test, intradermal injection test must be strictly controlled; the dose should be strictly controlled during the test, and should be prepared for rescue and other rescue.

Differential diagnosis

1, vagus vaginal vaginal discharge (or vagus vaginal collapse, vasovagal collapse): more occurs after the injection, especially when the patient has fever, loss of water or low blood sugar tendency, the patient often pale, nausea, cold sweat, and then It can be fainted and easily misdiagnosed as anaphylactic shock, but this disease has no itching or rash. The fainting is improved immediately after lying down. The blood pressure is low but the pulse is slow. These are different from anaphylactic shock. Atropine can be used for vagus vaginal fainting. treatment.

2, hereditary angioedema (hereditary angioedema): This is an autosomal-inherited disease that lacks the complement C1 esterase inhibitor, patients can be suddenly stimulated by some non-specific factors (such as infection, trauma, etc.) It is characterized by angioedema of the skin and respiratory mucosa. Due to obstruction of the airway, patients often have wheezing, shortness of breath and extreme breathing difficulties. They are quite similar to anaphylactic shock, but the onset is slower. The patient has a family history or a history of childhood attacks. There is usually no drop in blood pressure or urticaria at the time of onset, which can be differentiated from anaphylactic shock.

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