Anaphylactic shock lecture
Platelet agglutination stimulates platelet release histamine and other mediators, increases vascular permeability, spasms of smooth muscles and bronchi.
Anaphylactic shock (SPV) is the most serious allergic event, easily fatal if not diagnosed and handled promptly. The critical nature of anaphylaxis causes confusion for everyone, including physicians and patients' relatives. Illness occurs quickly, immediately or 30 minutes after taking drugs, testing, being stung by a bee or after eating strange food. The earlier symptoms appear, the more severe the disease, and the higher the mortality rate. The routes of the drug into the body: intravenous, intramuscular, subcutaneous, intradermal, oral, inhalation, topical, eye drops, vaginal placement, etc. can all cause anaphylaxis, however sugar Intravenous injection is the most dangerous. Medicines, especially antibiotics, are the main cause of anaphylaxis. So, anaphylaxis is an emergency that needs to be handled quickly and promptly because it easily leads to death from acute respiratory failure and hypotension.
Anaphylaxis is a form of a rapid type allergic reaction (type regain, anaphylaxis) that arises when there is a second entry of an allergen into the body. Anaphylactic shock is characterized by a drop in blood pressure, hypothermia, cardiovascular smoothness, increased vascular permeability and smooth muscle spasm. However, in fact, there are many cases where patients who have just started taking the drug for the first time but have had anaphylaxis are due to their previous hypersensitivity to a certain allergen whose structure is similar to that of the drug, for example, people. The disease has been infected with the fungus penicillium from the environment by ingesting or inhaling the fungus.
Mechanism of pathogenesis
Immediate hypersensitivity reactions often result in the release of mediators from mast cells and basophils, which are by the basis of stimulation of the allergen to IgE antibodies.
Allergens are substances of an antigenic or non-antigenic nature that are capable of causing an allergic state (stimulating IgE-specific antibody formation).
IgE antibody is the most important antibody participating in allergy mechanism discovered by Coca in 1925. The human reagin is IgE, which was discovered by Ishizaka in 1967. In allergic diseases, the level of IgE in serum increases very high. The result of the association of the allergen with the IgE antibodies on the mast cell membrane is the release of a series of chemical mediators.
Figure. Mechanism of anaphylaxis
The result of the above allergic reaction is a series of chemical mediators (mediators) released from the mast cells and basophil such as histamine, serotonin, bradykinin, leukotriene, slow-acting anaphylaxis (SRS-A): slow-reacting substances of anaphylaxis), prostaglandins, platelet-activating factor (PAF - platelet-activating factor) ... these substances dilate the vessels, spasm of bronchial smooth muscles, urticaria, Quincke oedema ... sieving of anaphylaxis.
The following are the physiological effects of some chemical mediators from mast cells and basophil in anaphylactic shock:
Stimulate receptor H1:
Vasodilation, bronchial mucosa oedema.
Increased vascular permeability, increased secretion.
Spasms of smooth bronchial muscles.
Urticaria, Quincke's oedema, erythema.
Stimulate the H2 receptor:
Increased heart rate.
Increased myocardial contractility.
Increased gastric secretion.
Play an important role in the anaphylactic shock response of humans and animals. This substance causes spasm of bronchial smooth muscle, increases the permeability of the vessel wall, spasms of blood vessels of the heart, lungs, brain, kidneys, stimulates the nerve endings causing itching.
Smooth muscle contraction slower than histamine, vasodilation, hypotension, increased vascular permeability.
Contraction of bronchial smooth muscles increased bronchial reactivity (PGD2 causes bronchospasm).
PAF (platelet-activating factor)
Platelet agglutination stimulates platelet release histamine and other mediators, increases vascular permeability, spasms of smooth muscles and bronchi.
Increases vascular permeability and IL1 production, bronchospasm.
Bronchial smooth muscle contraction.
Increases the effect of histamine.
Anaphylaxis occurs in many internal organs in the body due to the impact of the above chemical mediators:
On the cardiovascular system dilate the vessels, drop in blood pressure, heart failure.
Respiratory system: bronchospasm causes suffocation.
On the nervous system: cerebral vasoconstriction causing headaches, coma.
On the digestive system: increase secretion, increase intestinal motility causing diarrhoea, abdominal pain. Disrupting the bladder and anus circular muscles, causing urinary incontinence.
Skin: causes urticaria, Quincke's oedema, itching.
The cause of anaphylactic shock
There are many causes, of which medicine is the leading one, followed by food and insect venom.
List of drugs that cause anaphylaxis
Anaphylaxis and drug allergy complications occur more and more with serious consequences, many deaths. Medicines entering the body (all hapten) must combine with proteins in serum or tissue to become complete allergen with antigenic properties causing anaphylactic reactions.
The drugs cause more and more anaphylaxis, the following are common ones: Penicillin, Streptomycin, Ampicillin, Vancomycin, Amoxycillin, Chloramphenicol, Cephalosporin, Tetracycline Claforan, Trimazon Neomycin, Nevigram Kanamycin, Erythromycin Lincomycin, Polymyxin B Gentamycin.
Nonsteroidal anti-inflammatory drugs: salicylates, colchicine, mofen, indomethacin.
Vitamins: Intravenous vitamin C is the cause of anaphylactic shock common in our country, followed by vitamin B1, vitamin B12 in the form of injection.
Infusion types: glucose, nutrisol, alvesin, bestamin, Tryphosa.
Anaesthetics: procaine, novocaine, lidocaine, thiopental.
Iodine contrast: visotrate.
Hormones: insulin, ACTH, vasopressin.
Types of vaccines, serums: rabies vaccine, tetanus prevention, anti-leukaemia serum, tetanus.
Drugs with low molecular weight: dextran, gamma globulin, visceral extracts.
Enzymes: trypsin, chymotrypsin.
Other drugs: visceralgin, aminazin, paracetamol, efferalgan-codein.
Other causes of anaphylactic shock
Food: There are many types of foods of animal and plant origin, causing anaphylaxis such as mackerel, tuna, sticky rice, shrimp, shrimp, shrimp, snail, eggs, milk, pupa, pineapple, potato, mango peanuts, soybeans, additives, etc.
Insect venom: anaphylactic shock occurs due to the bite of a bee, snake, spider, or scorpion.
The clinical scene of anaphylaxis caused by insects and other causes (medicine - food) is essentially the same.
Clinical features of anaphylaxis
Anaphylaxis associated with immediate hypersensitivity reactions can occur in hypersensitive individuals, it is possible that immediate atopy (atopy) hypersensitivity reactions can occur locally or systemically at all. The species with the most common features is a spasm of bronchial smooth muscle and increased vascular permeability.
Clinical symptoms of anaphylaxis are diverse, appearing in many internal organs.
The severity of shock depends on the sensitivity of the individual, the amount and rate of absorption of the allergens or foreign substances into the body, on the other hand, mainly on the time of proper treatment. Early signs to watch out for: itchy hands, feet, numbness of the lips, tongue, difficulty breathing, tachycardia, feeling restless, panic.
Common clinical symptoms in some organs
Oedema of the pharynx, vocal cords, tracheal oedema, tracheal spasm, bronchiolitis, pulmonary tingling, snoring like bronchial asthma. The patient found dyspnoea, asphyxia, cyanosis, acute respiratory failure, decreased alveolar ventilation. In a few cases, acute pulmonary oedema may be present due to increased vascular permeability.
Circulatory and hemodynamic system:
Vasodilation is often present early in anaphylaxis as a result of chemical mediators, vasodilation, and rapid increases in vascular permeability leading to a decrease in circulating volume (total blood volume and blood volume There is a marked decrease in anaphylaxis), tachycardia or arrhythmia, and decreased arterial pressure due to a decrease in ejection volume.
Hypoxemia, hypovolemia leading to acidosis and a decrease in myocardial contractility are severe stages of anaphylaxis. So, hypovolemia is a major factor in anaphylaxis.
Headache, dizziness, limb tremor, drowsiness, struggles, slurred speech, convulsions all over the body, possible fainting or coma.
The substances that cause anaphylaxis are food, fruit and medicine, the patient has severe abdominal pain, vomiting, nausea, diarrhoea, incontinence, sometimes gastrointestinal bleeding.
Systemic urticaria, Quincke's oedema, or itchy erythema.
There may be fever, sweating, chills, fatigue, etc.
Anaphylaxis is divided into 3 levels of development: mild, moderate and severe
Symptoms of headache, fear, dizziness, urticaria, pruritus, Quincke's oedema, vomiting or nausea, abdominal pain, urinary autonomy, tachycardia, drop in blood pressure, difficulty breathing.
Patient panic, fear of death, dizziness, tingling all over, difficulty breathing, convulsions, sometimes coma, abdominal pain, cyanosis, pale mucous membranes, dilated pupils, small tachycardia, blood pressure drop or can't be measured.
Happened in the first few minutes at lightning speed. The patient is lethargic, choking, cyanotic skin, blood pressure not measured, death after a few minutes, rarely lasting a few hours.
Adrenalin must be used immediately, whether mild or moderate or severe
Note late events occurring after anaphylaxis such as allergic myocarditis, nephritis, glomerulonephritis. These complications can lead to death. There were cases of anaphylaxis that was treated but 1-2 weeks later, bronchial asthma, urticaria, Quincke's oedema recurred several times.
In summary, anaphylaxis is a consequence of hypoxia, vasodilation, acute massive increase in vascular permeability and bronchial smooth muscle spasm. So, the cause of rapid death is bronchospasm, causing respiratory failure and prolonged drop in blood pressure.
Diagnosis of anaphylaxis
Must be prompt, timely, mainly based on the rapid appearance within minutes of the aforementioned symptoms after exposure to the allergen that causes an anaphylactic reaction (drugs, food, chemicals used or insect). coincidence). However, diagnosis is difficult when these symptoms are not sufficient, such as urticaria or acute bronchospasm in an asthmatic patient. Therefore, when making a diagnosis, it is necessary to pay attention to all the symptoms, especially heart failure, blood pressure drop after the drug or foreign allergens into the body.
Treatment of anaphylaxis
Urgent, spot and immediate use of adrenalin.
Adrenalin should be used immediately as quickly as possible because adrenalin immediately alters severe signs of anaphylaxis such as bronchospasm and hypotension by increasing cAMP in mast cells and basophil. The increase in cAMP inhibits the release of chemical mediators from these cells. Adrenalin also stimulates and α systems. The 1 stimulation of adrenaline increases myocardial contractility, increases circulating volume, and regulates heart rate. Α stimulation increases peripheral resistance, increases diastolic pressure, increases perfusion to the coronary arteries, resulting in an increase in cardiac output, increased blood pressure, and increased oxygen transport to the organs.
Emergency regimen for anaphylaxis
(According to Circular 08 dated 4-5-1989 of the Ministry of Health of Vietnam).
Treatment on the spot:
Immediately stop contact with allergens! (drugs are used for injection, oral, topical, eye drops, nose).
Have the patient lie in place.
Adrenalin is the basic drug to combat anaphylaxis.
Adrenalin 1 / 1,000 solution, 1ml = 1mg ampoule, injected under the skin immediately after the appearance of anaphylaxis with the following dose:
1/2 - 1 tube in an adult.
Not more than 0.3ml in children (1ml (1mg) tube + 9ml distilled water = 10ml then inject 0.1 ml / kg).
Or adrenalin 0.01 mg/kg for both children and adults.
Continue injecting adrenalin dose as above every 10-15 minutes until blood pressure returns to normal.
Warm incubation, low head, high legs, blood pressure monitoring every 10-15 minutes (lying on your side if vomiting).
If the shock is too severe and threatens death, in addition to the subcutaneous route, adrenaline 1 / 10,000 solution (diluted 1/10) can be injected intravenously, through the endotracheal tube or through the ring of the ring.
Depending on the medical equipment conditions and the professional and technical qualifications of each level, the following measures may be applied:
Management of respiratory failure:
Depending on the route and the degree of difficulty breathing, the following measures can be used:
Nasal oxygen breathing, suffocating.
Squeeze the Ambu bulb with oxygen.
Endotracheal intubation, artificial ventilation. Open the trachea if glottis is present.
Slow intravenous infusion of aminophylline 1 mg / kg / hour or terbutaline 0.2 mcg / kg / min. Can be used:
Terbutaline 0.5mg, 1 tube subcutaneously in adults and 0.2ml / 10kg in children. Re-inject after 6-8 hours if breathing is not less difficult.
Terbutaline and salbutamol spray 4-5 times a day, 4-5 times a day.
Establish an intravenous line
Adrenalin for blood pressure maintenance begins with 0.1 mg / kg / min, rate adjustment for blood pressure (approx. 2 mg adrenalin / hour for adult 55 kg).
Methylprednisolone 1-2mg / kg / 4 hours or:
Hydrocortisone hemisuccinate 5 mg/kg / hour intravenously (can be intramuscularly at baseline). Use a higher dose if the shock is severe (2-5 times more).
NaCl 0.9% 1-2 litters in adults, not more than 10ml / kg in children.
Diphenhydramine 1-2mg, intramuscularly or intravenously.
Drink activated charcoal 1g / kg of body weight if the allergen is ingested.
Apply pressure to the limb above the injection site or the venom's inlet.
Follow up for at least 24 hours after blood pressure has stabilized.
After first aid should take advantage of the thigh intravenous route (because the vein is large, located inside the femoral artery, easy to find).
If blood pressure still does not rise after sufficient infusion and adrenalin, then additional plasma, albumin (or blood if blood loss) or any other available polymers are available.
Nurses can administer adrenaline subcutaneously according to the regimen when doctors and doctors are not present.
It is important to ask for a history of allergy and an anaphylaxis first aid kit before taking medication.
Measures to limit drug allergy and anaphylaxis
Propagating the rational and safe use of drugs as prescribed.
Before prescribing the drug, the physician must carefully exploit the patient's history of allergy. In patients with a history of allergy to drugs or food, it will be easy to have allergies when using the drug.
Anaphylaxis must be prevented in hypersensitive patients, considering the dosage, route of administration and the rate of absorption of the drug used in treatment and diagnosis. When a patient with a history of anaphylactic reaction to a drug even mildly tries to avoid re-use, it is important to understand cross-drug interactions (e.g., penicillin and cephalosporin both share a lactam loop.).
Before injecting antibiotics, a prick test, a negative test is injected. Have anaphylaxis medicine and first aid kit available.
While injecting drugs, if you see unusual feelings (restlessness, panic, fear ...), you must stop the injection and promptly handle it like anaphylaxis).
After injection, let the patient wait 10-15 minutes to prevent anaphylactic shock from occurring later.
Contents of the first aid kit for anaphylaxis
Adrenalin 1mg - 1ml: 2 ampoules.
10ml distilled water: 2 tubes.
10ml sterile syringe pump: 2 pcs; 1ml: 2 pcs.
Hydrocortisone hemisuccinate 100mg or methylprednisolone (Solumedrol 40mg or depersolon 30mg: 2 ampoules).
Disinfection means (cotton, alcohol bandage).
Emergency regimen for anaphylaxis.
Other equipment: Depending on the medical equipment conditions and the professional qualifications of each level, the treatment rooms should have the following medical equipment:
Salbutamol or terbutaline spray pump.
Ambu shade and mask.