Pediatric Allergies
Introduction
Introduction to Pediatric Allergy Allergy (anaphylaxis) is sometimes translated into anaphylactic shock or severe allergic reactions, which is the most urgent event in clinical immunology. It is now described as a group of severe clinical symptoms involving multiple immune or non-immune mechanisms, often sudden, involving multiple target organs, and is a clinical syndrome with multiple inducers and pathogenic mechanisms. basic knowledge The proportion of illness: 0.12% Susceptible people: children Mode of infection: non-infectious Complications: shock, laryngeal edema
Cause
Causes of pediatric allergies
(1) Causes of the disease
1. Food: Any food, including Chinese cabbage, may induce allergies, but the most common allergies are milk, egg white, peanuts and other legumes, nuts and other foods.
2. Vaccines related to poultry: There are measles, mumps, yellow fever and influenza vaccines. The main causes of adverse reactions are avian proteins in vaccines and hydrolyzed gelatin, sorbitol and neomycin in certain vaccines. Medical history can often provide clues.
3. Hymenoptera: If the bee can cause local or systemic allergies in the sensitized person, it can be diagnosed by various kinds of bee venom.
4. Drugs: Among them, -lactam antibiotics and aspirin/non-steroidal anti-inflammatory agents are the most common.
5. Skin test and IT: Because allergens used are or may be allergens of allergies in children, it is easy to induce allergies.
6. Exercise: A new class of patients has recently been discovered. They have wheal and other allergic symptoms called exercise-induced anaphylaxis (EIA) after exercise. Some patients have exercise after meals, and The type of food has nothing to do, while others respond to exercise after eating special foods. It is said that exercise relies on food-induced allergies. The prevention method is to not exercise within 2 hours after a meal.
7. Cold: It can also induce allergies. In light cases, the body will be whipped and itchy, and it will disappear quickly after warming. In severe cases, systemic allergy can be induced. Such patients should avoid excessive cold and swimming. Should warm the body as soon as possible.
8. Natural rubber: 99% is latex from oak. The diagnosis relies on skin prick test. In vitro detection of latex-specific IgE is not as sensitive as skin test. At present, there is no latex extract in China, and rubber products can be used for rapid patch test. 20 to 30 minutes observation, latex is the manufacture of various rubber gloves, medical rubber catheters, anesthesia masks, toys, pacifiers and other raw materials, therefore, any child is sucking pacifiers, blowing balloons, playing with rubber toys or Symptoms appear after other latex products, suspected and allergic to latex. Those who are allergic to latex will also be allergic to various vegetables and fruits.
9. During general anesthesia of surgery: 90% of allergies occur within 3 minutes of intravenous administration, often involving muscle relaxants. The latex allergic reaction usually occurs between 20 and 60 minutes. The systemic response during 100 anesthesia is observed as follows: Circulatory collapse 68%, body flushing 55%, skin edema (mainly involving the face) 55%, bronchial obstruction 23%, cardiac arrest 11%, neuromuscular blocking drugs such as chlorosuccinylcholine (Scolin), Opioid painkillers, antibiotics or protamine used during surgery, latex, blood transfusions and anesthetics are also susceptible.
10. Primary recurrent hypersensitivity: Many of them are only temporarily unable to find the cause. Therefore, the diagnosis is mainly to exclude the test. Some patients have severe asthma reaction after meal, which may be caused by bisulfite in food. Other recurrent episodes of unexplained shock may be caused by potential penicillin in milk and so on.
(two) pathogenesis
Many allergies are mediated by IgE. MC degranulation releases major mediators and other vasoactive amines, LTs, PG and PAF. The half-life of histamine in plasma is very short, but it has been determined to cause allergies in humans. Important media, as for the mechanism of non-IgE-mediated allergy is not very clear, presumably due to the activation of complement caused by the production of anaphylatoxins C3a and C5a, these molecules can directly increase smooth muscle contraction and vascular permeability, neuropeptides Such as SP, vasoactive intestinal peptide (VIP), somatostatin (SOM) have strong ability to induce mediator release, especially the ability to stimulate the rapid release of histamine, aspirin and non-steroids The mechanism of allergic reactions caused by anti-inflammatory agents is not fully understood. The promotion of mast cell secreting agents such as opioids is thought to be due to the rapid release of histamine, but many scholars believe that host sensitivity to media is more important. .
The main pathological changes in human fatal allergy include acute lung over-expansion, laryngeal edema, visceral hyperemia, pulmonary edema, alveolar hemorrhage, urticaria/angioedema, but some patients have no pathological changes, and some have found using advanced histopathological techniques. 80% of the fatal cases have myocardial damage.
Prevention
Pediatric allergy prevention
Because this disease can be life-threatening, prevention is very important. Collecting an accurate and complete medical history is not only for diagnosis, but also for prevention. It is important to find out the regularity and cause of allergic reactions, and to detect induced substances, especially potential. Inducing substances and their cross-reactants and thus avoiding exposure. In addition, most drug-induced allergic reactions cannot be diagnosed by skin test. When suspected patients need to take drugs, the types should be as few as possible, which is conducive to diagnosis and prevention. Systemic allergic reactions have occurred during the course, and should be reduced as appropriate, and at least 20 minutes after the injection, patients with severe allergic reactions may have a serious allergic reaction at any time. A first aid kit should be prepared. A syringe containing 1:1000 adrenaline and a beta 2 inhaler are included for emergency use.
Complication
Pediatric allergy complications Complications, shock, laryngeal edema
Severe cases can occur shock, laryngeal edema, asphyxia, arrhythmia, myocardial ischemia, cardiac arrest, convulsions, loss of consciousness, multiple organ failure and so on.
Symptom
Pediatric allergy symptoms Common symptoms Skin itching convulsions fatigue Anxiety Children eczema Dizziness Edema Gastrointestinal symptoms Hypotension Sound hoarseness
The onset, manifestations and processes of this syndrome are different, related to the intensity of allergens, the health status and genetic quality of patients, and the general symptoms begin very quickly, which may occur a few seconds after exposure to the inducer. After 1h, some patients have aura before symptoms appear, but these early symptoms such as anxiety, dizziness, patients are often unclear, the symptoms are systemic, varying in severity, most patients start with skin symptoms, skin flushing and often With sweating, erythema, itching is especially common in the hands, feet and groin, urticaria / angioedema is temporary, generally no more than 24h, severe cases of cyanosis, upper respiratory symptoms have mouth, tongue, throat or throat edema, which throat Edema from hoarseness, aphasia to asphyxia, the latter is the main cause of death; lower respiratory symptoms are chest tightness, irritating cough, wheezing, respiratory arrest, etc., cardiovascular symptoms have hypovolemic hypotension ( In severe cases, no response to the booster), arrhythmia (common heart rate accelerated up to 140 beats / min, such as patients with beta blockers can occur slow pulse), myocardial ischemia, cardiac arrest Gastrointestinal symptoms include nausea, vomiting, abdominal cramps, and diarrhea. Abdominal pain is often an early manifestation of the disease. Gastrointestinal symptoms are uncommon and never appear alone. The genitourinary system shows urinary incontinence and uterine contractions. Neurological symptoms include anxiety, convulsions, loss of consciousness, etc., patients are fatigued and weak, in addition, patients may also have some mental symptoms due to temporary cerebral hypoxia.
The above symptoms and signs can exist either alone or in combination. Most of the serious reactions involve respiratory and cardiovascular reactions. Those who begin to lose consciousness can die within a few minutes, or can occur within a few days or weeks, but are generally allergic. The later the symptoms of the reaction start, the lighter the degree of the reaction, and the late reaction can occur again 4 to 8 hours after the early allergic reaction has dissipated.
Any route including oral, intravenous, dermal, topical, inhalation and mucous membrane contact can cause allergies. In severe cases, it is easy to induce shock in children, and children are more likely to be involved in the respiratory tract. Therefore, serious cases should be especially alert to respiratory symptoms, such as patients with airway obstruction. The chest X-ray may indicate excessive lung inflation and/or atelectasis. If the patient has shock, due to massive exudation, blood concentration may be observed, occasional bleeding, and indeterminate, may have myocardial ischemia or injury.
Examine
Pediatric allergy check
Non-specific diagnosis
Such as: blood, sputum, nasal discharge, eye secretions, stool, middle ear secretions, etc. eosinophilic examination; blood, other body fluids or secretions of histamine content determination; serum and secretions IgE, IgA, IgG, IgM content determination; lung function test; T lymphocyte transformation test; complement Ch50, Ch2, C3, C4 determination; macrophage migration inhibition test; leukocyte phagocytosis index; blood and urine 17 ketone, 17 hydroxysteroid determination Plasma protein electrophoresis; erythrocyte sedimentation test; anti-hemolytic streptococcal antibody titer determination in blood; rheumatoid factor determination; antigen-antibody complex determination; blood lupus erythematosus cell examination; and routine examination of blood, urine, stool, etc. These detection methods have their own diagnostic significance for different allergic diseases and can be selected.
2. In vivo specific diagnosis
At present, the most extensive in vivo specific diagnostic method is used in the clinical practice of allergic reaction. The skin test method is the first, and there are various test methods other than skin, including nasal mucosa, bronchial mucosa, conjunctiva and oral mucosa test.
The principle of in vivo specific diagnosis is: in the skin and body fluids of exogenous allergic patients, there is a specific antibody called responsive or skin sensitive antibody, that is, specific IgE, when the corresponding antigen enters the skin through different routes. , that is, combined with the responsiveness, release the allergic reaction medium, produce local allergic reaction, make the skin congestion, edema, exudation, formation of papules, erythema around the papule, which is the positive reaction of specific skin test, due to entry The amount and concentration of antigen in the skin are strictly controlled, so this test method is safe, the reaction only occurs locally, but there are also very few highly sensitive patients, even when strictly controlling the antigen concentration and dose. Under the circumstance, there may still be a strong systemic reaction, even those who have died of anaphylactic shock due to skin tests. Cases of shock death caused by penicillin skin test have occurred, but we have been working on clinical allergy for more than 40 years. , the use of specific skin tests has not been hundreds of thousands of times, has not happened one Those who have caused fatal reactions by skin test, occasionally those who have asthma attacks or urticaria due to specific skin tests, can be controlled in time after proper treatment, which shows that the current methods, such as strict control procedures To make the necessary emergency preparedness, it is generally safe.
(1) Indications for in vivo specific diagnosis:
Patients with exogenous allergies in 1-speed or patients with contact allergies in delayed allergic reactions.
2 The patient should not be in a strong allergic attack during the test.
3 has not used corticosteroids, antihistamines, adrenaline, ephedrine or other similar drugs in the near future.
4 The skin of the patient's test site is not in a state of non-specific irritability, such as obvious skin scratches, etc. Such patients are prone to false positive reactions if they are skin tests.
5 The skin of the patient's test site should be free of eczema, urticaria or other skin damage.
(2) Types and methods of in vivo specific diagnosis:
1 patch test: This is an older method, also known as patch test, as early as 1896, Swiss dermatologist Jadasson used this method to investigate the sensitizing cause of patients with suspected drug allergy, this It is a fairly simple and safe method that is still in use today.
The specific method of the test is: for suspected allergic drugs, food or inhaled substances, if it is a solid substance, first research it into fine powder or pulverize, then take a small amount and place it on the skin of the forearm of the patient's forearm, and then put a drop of 0.1mol. /L sodium hydroxide solution or physiological saline, gently mix the powder with water, wait for it to be semi-dry, cover a piece of non-absorbent cellophane or plastic film, and then wrap it with gauze to keep the test object in close contact with the skin for 24~48h Then remove the dressing and observe whether the skin of the contact part of the test substance has redness, rash, itchy skin, ulceration, etc. If there is any such reaction, it is a positive reaction, such as mild redness, rash, itchy skin, once Positive reaction, if there is scattered small rash, obvious itching, is a second positive reaction, if there is a piece of rash or herpes, it is a three-degree positive reaction, such as skin exudation, ulcer, necrosis, etc. It is a four-degree positive reaction. For example, when the dressing is uncovered at 48 hours, no special skin changes have been observed. The contact time can be extended for another 24 hours. After the spotting for 72 hours, it is observed again. Reaction, that is a negative.
Recently, when we applied patch tests on fabrics, man-made fibers and other solid suspicious contact allergens, we used simulated artificial sweat as a wetting agent for spotting, which is more similar to the application of 0.1mol/L sodium hydroxide or normal saline. The natural contact and absorption state of allergens at the time of onset has a better effect. The formula of artificial sweat is: sodium chloride 3g, lactic acid 2ml, sodium sulfate 1g, urea 2g, stearic acid 2ml, adding distilled water, so that the total amount becomes 1L.
For the original allergen of liquid contact, it can be directly applied to the surface of the skin and then wrapped. The results of the patch test should be observed. In addition to the immediate response after the application of the adhesive is released within 24 to 48 hours, After 12 to 24 hours after the removal of the patch, look at whether the local skin has a delayed positive reaction.
The disadvantage of the patch test is that there are many test allergens that cannot be absorbed by the skin, and thus often result in false negatives. Conversely, some allergic principles have certain non-specific stimuli on the skin and may cause false positive reactions. Moreover, each time the tested variety is limited, the observation time is longer. For some patients with strong positive reaction, the applicator should be removed in the early stage of the reaction, without waiting for 24h or 48h, so as to avoid the patient suffering from excessive reaction.
In recent years, we have also used the plastic aluminum film blister pack for packaging pills to wash and dry the empty capsules, and cut them into caps for use. In use, put a small group of clean absorbent cotton in the small cap, and then change the required test. The original solution was dropped on the cotton ball with a dropper, and then the small cap was buckled on the skin of the forearm ventral surface, and a small cap was used as a control to buckle the forearm at the same time, and the cap was fixed with a tape, and was exposed for 24 hours and 48 hours respectively. Open the small cap to observe the skin reaction. In addition, you can also use the commercially available Band-Aid bandage to remove the gauze piece containing Ravennor in the center and replace it with a layer of clean white gauze, and drop the antigen solution to be tested on the gauze. Seal it on the skin of the forearm, and uncover the observation reaction at regular intervals. The above method is stable and the material is easy to obtain. It is easy to operate and can be tried. Some hospitals also have a cup-shaped spotted cap made of thin aluminum sheets. Skin tester.
The patch test is most suitable for contact allergic reaction. In fact, this method can be regarded as a skin challenge test for contact allergic reaction. In recent years, cosmetic allergy, chemical allergy and many occupational allergic reactions are related to skin contact. The adaptability of the test is wide. The current difficulty is how to determine the optimal concentration of the test antigen is a key problem. If the concentration is too low, it will cause a false negative reaction. If the concentration is too high, it can cause a false positive reaction. The International and North American Contact Dermatitis Research Group (International and North American Contact Dermatitis Research Group) has studied the best patch concentration for a few chemical agents, and some manufacturers have made this ointment for patch skin test.
2 scratch test: This is also a relatively simple and safe method, because the test does not require disinfection or special equipment, local pain, no bleeding, the result is more accurate and faster than the patch test, it is more suitable In children, the test can be performed on the lateral skin of the patient's forearm. For example, in infants, the area of the shoulder blade on both sides of the back can be utilized because the skin area of the arm for testing is too small.
Method of operation: use a blunt edge ophthalmologic cataract knife or a needle for blood collection in a laboratory. If necessary, use ordinary thick needles or injection needles instead. Currently we use acupuncture for sale on the market. The triangular needle used by the physician is recommended because it has a relatively thick needle handle and a moderately pointed tip for easy grip and damage.
During the test, the needle is placed on the surface of the selected skin, and the length of the two strokes is 3 to 5 mm in parallel. If the scratch is scratched, it is also cross-shaped into a cross or X shape, as the sample is powdery. For allergens, first drop 1 drop of 0.1 mol/L sodium hydroxide, normal saline or artificial sweat on the skin of the scratching area, then use a clean metal spoon to take a small spoonful of antigen and sprinkle it on the liquid. Mixing, we currently use the aluminum ear spoon sold on the market, which is cheap and suitable. The blunt part of the other end of the ear spoon can be used for mixing. If the liquid antigen is tested, drop 1 drop at the scratch. The antigen can be dried naturally.
After the antigen is in contact with the skin for 15 to 20 minutes, the reaction can be observed. The judgment of the scratch test results often has their own experience and standards. Our usual standards are:
A. The skin at the scratch is slightly raised, and there is a (+) when there is a reddish ray around it.
B. There is a papule-like bulge at the scratching area, the length of which exceeds the range of scratching, and there is obvious erythema around the papule, which is (++).
C. At the scratch site, the papules have pseudopods, and the erythema responders with wide, reddish and irregular edges are (+++).
D. At the scratch site, there are more than 2 pseudo-footes, itching, and the surrounding skin is red and swollen, which is (++++).
Precautions for scratch test: If multiple antigen tests are performed at the same time, the order and location of each antigen must be clearly remembered; if necessary, mark on the skin to avoid confusion, such as skinning with multiple antigens. Try, the order of each antigen should be memorized. For example, when the test is performed on the outer skin of the upper arm, the procedure of arranging the antigen is customarily from top to bottom, from left to right, every 5 kinds of lines, each arm 2 lines inside and outside, can be used for a total of 10 types, both arms can be used for skin test of 20 kinds of antigens at the same time, such as using the back shoulder skin test, if the subject is an adult, from top to bottom, each line can be made 1O Kinds, from left to right, a total of 6 lines, so each time you can make a skin test of 60 antigens at the same time.
The needles and spoons used in the scratching should be prepared in an tens to hundreds of sets. After use, the antigens are mixed to prevent cross-reaction. The distance between the upper and lower sides of each test is at least 3 to 5 cm. The test department does not need to use alcohol to disinfect the skin, so as to avoid the congestion reaction caused by alcohol, and interfere with the observation. For those patients whose skin is too dirty, they can be cleaned with water and soap first. After the test, if there is a strong reaction at the endoscopic test 15 minutes after the test. The antigen can be wiped off with cotton and distilled water to prevent further development of the reaction.
3 prick test: also known as puncture test (puncture test), this method is actually an improvement of the scratch test, because the method is simple and convenient, in recent years foreign foreign allergic community has adopted this method quite a lot The method is to first drop a drop of antigen on the skin test site, then use a special point pricking needle to puncture the center point of the skin with the antigen, press the needle tip to the skin for about 1 mm, and then gently pick the epithelium. It is not necessary to be too deep, and it is not bleeding. Some people also use the 16 or 17 flat needle (such as the needle for injection of contrast agent used in the parotid duct angiography) for the prick test. When using the needle, put the needle into the antigen bottle. The needle tube is filled with a small amount of antigen solution, and then the needle is used to stab the patient's skin, and the effect is satisfactory.
Recently, we also used a thin glass tube with a diameter of 3 mm that was sawed into a small section for puncture test. The advantage is that the tube wall is smooth, easy to clean, no rust, less pollution, and cheaper; if used for skin testing for children, It also does not cause children to be scared. Because the glass tube is cheap, some can be discarded every time it is used, no longer disinfected and reused. When testing, care should be taken to prevent the glass tube from breaking, the observation standard and precautions of the prick test. As with the scratch test, with the promotion of the puncture test, in recent years, disposable stainless steel puncture needles with different shapes have been manufactured at home and abroad for use. It is very convenient to use after discarding. The depth of the needle is limited by the shoulder of the needle handle. It can be controlled, the prick test is abroad, and Europe is used more widely than North America.
Since the 1980s, the prick test has been increasingly promoted, and the pricking devices have been improved. In the United States, a plastic pricker called Multitest has been designed, which is divided into two rows, each with 4 puncture needles. The needle is made into a brush shape, and is equipped with 8 kinds of commonly used allergen test liquids. When operating, 8 kinds of allergens are respectively dropped on 8 point needles, and pressed on the skin of the forearm of the patient's forearm. It can be used for 8 kinds of allergens. Italy also designed a plastic pricking device that can be used for 32 different allergen tests. The puncture needle is conical, and the end of the needle has a thicker "shoulder". To control the depth of the needle, this point is called the Pellow tester.
Pharmacia of Sweden has coated all kinds of allergens on the stainless steel puncture needles, and separately sterilized and sealed the package. When the test is opened, the pricking needles can be taken directly on the patient's skin without any need. Any liquid allergen, this prick test is called "dry prick test", which is extremely convenient. Its advantage is also that the antigen is in a dry state and is not easily degraded, so the effective period can be increased to 3. In the year, all the above-mentioned pricking devices are single-use, no antigen crossover or operational pollution, and are equipped with negative and positive controls. Because the puncture test operation is simpler and safer than the intradermal test, it is more suitable for children. Some areas have replaced the intradermal test.
4 intradermal test (intradermal test or intracutaneous test): This is currently the most widely used in vivo specific test, the results are more reliable, the test dose control is more stringent, we have been clinically used for many years This method is used for specific allergen examination. It can be used for testing food, inhalation, certain drugs and insect venom. The operation method is as follows:
The outer skin of the upper arm is also generally used as the test area, so that the patient sits sideways, exposes the whole arm, disinfects the skin with 70% alcohol, and extracts the test solution with a tuberculin syringe and a 26 or 27 intradermal needle with a needle length of about 1 cm. At present, disposable syringes have been widely used in the West, and disposable syringes are gradually being promoted in China. For safety, it will soon be popularized in China. The concentration of test solutions varies according to their respective experiences. At present, we use inhalation. Sexual antigens, including house dust, feathers, fur, old cotton wool, tobacco, fungi, pollen, etc., at a concentration of 1:100, for food-free antigens containing no irritating vegetables, fruits, grains, etc., at a concentration of 1:10, For high-protein foods such as fish, meat, shrimp, crab, egg, milk and onion, garlic, ginger, and pepper, or irritating foods, use a concentration of 1:100 for individual antigens with strong potency, such as Artemisia Pollen, sputum, etc., we use a concentration of 1:1000 or 1:1 million, and some antigenic substances with strong potency, such as aphid infusion, we have used a concentration of 1:100,000, each allergic reaction Clinical worker There must be a general understanding of the potency of the various antigens used in order to control the appropriate test concentration to prevent adverse reactions or accidents.
According to the customary procedure, the top-down, from left to right, one by one, after each test area with an intradermal needle pierced into the superficial epidermis, the needle is about 2 ~ 3mm, push the test solution about 0.01 ~ 0.02 Ml, the distance between each test zone is at least 3cm, and the reaction result can be observed 15min after skin test. The judgment criteria of the reaction result are as follows:
A. The subject's skin papules are less than 5 mm in diameter, no erythema is formed around, or only a slight erythema reaction is negative.
B. The skin papules are between 5 and 10 mm in diameter and are surrounded by light erythema. (+).
C. The skin papules are between 10 and 15 mm in diameter, and there are erythema reaction bands with a width of more than 10 mm, which is (++).
D. The skin papules are more than 15mm in diameter or the papules are irregular, and pseudopods appear. The erythema reaction band with a width of more than 10mm is (+++).
E. The local reaction is the same as (+++), and at the same time, the body reaction, such as skin itching, rash, skin flushing, belching, asthma attack and other symptoms, is (++++).
In the intradermal test, attention should be paid to the disinfection of the needle of the needle. The name and concentration of the antigen should be marked on the needle tube to prevent mutual mixing. In the allergology clinic, a large number of patients should be tested intradermally every day. Prepare a plurality of metal syringe boxes. After serial disinfection, insert syringes containing various antigens. The intradermal needles for injection should also be prepared in large quantities. If they are used once, they should be replaced. The syringes do not have to be replaced once per person. After the outpatient clinic, the intradermal needle should be checked for brows and bluntness. If it is found to be barbed or dull, it should be sharpened at any time to ensure the smooth progress of the next inspection.
After the skin test is completed, the patient should be observed for any systemic reaction within 15 to 20 minutes after the patient is waiting to observe the reaction, such as lip numbness, itchy palm, generalized itching, skin color flushing, cough, asthma, chest tightness, and thin pulse. If there is such a situation, the patient should immediately lie down and rest, and appropriate measures should be given according to the severity of the reaction. The lighter can acupuncture the palm of the patient's palm or the person, Yintang, Shixuan and other points, and have chest tightness and cough. Inhaled with isoproterenol or salbutamol (sulphate), severe cases should be injected with adrenaline, oxygen, or even artificial respiration, intravenous injection of adrenaline, etc. For more than 20 years, we are counting dozens In the intradermal test of 10,000 patients, although several cases of heavier skin test reactions have occurred, they are safely recovered due to timely treatment.
In recent years, we have acupuncture in the palm of our hand for a patient who has a systemic reaction after the skin test. It has received good results by using a 1.5-inch (1.5-inch = 3.3 cm) acupuncture needle into the center of the palm of both sides of the patient. The needle is about 1 inch, slightly twisted, and the needle is left for about 10 minutes. Generally, it is gradually recovered after 3 to 5 minutes after acupuncture. In addition, isoproterenol, salbutamol (salmatine), terbutaline (prophylaxis) Inhalation of aerosols is also effective for patients with asthma attacks after skin test, so disinfected acupuncture needles, isoproterenol, salbutamol aerosol, and epinephrine for injection, ephedrine (ephedrine) ) should also be prepared at the clinic at any time to prevent the occurrence of a physical reaction after the skin test.
Intradermal test should also prevent local infection, in addition to strict aseptic technique during operation, it is also necessary to check the skin test antigen for contamination at any time, because repeatedly using the needle to suck the antigen in the bottle, it can bring in pollutants for a long time. Every time you take the medicine, you should pay attention to observe whether the liquid is turbid or precipitated. Usually, the antigen should be stored in the refrigerator at about 4 °C. The skin test antigen should be used. After 1 month or so, it should be re-updated.
The doctors, nurses or technicians working in the allergy clinic should cooperate closely. The skin test is generally performed by a nurse or a technician. Once a special situation occurs in the test, the doctor should be reported to the doctor at any time to jointly take measures to collect the medical history or During the examination, if the patient is found to have a strong allergic reaction to something, the skin tester should also be reminded to observe the skin test, and if necessary, use a higher dilution antigen for the skin test or an intradermal test. Before the patch test or scratch test, to ensure safety.
In the intradermal test, air should be prevented from being injected into the skin; once injected, local skin may have a false positive reaction, and the false positive reaction of the skin due to the injection of air may sometimes be "splashing" because the air may be injected. Disperse into many small bubbles, smashing into the inner skin tissue, causing the skin erythema scattered into the stars, which is different from the flaky reaction that occurs after antigen injection. After careful observation, it can be distinguished from the true positive reaction described above. When the test is injected, the blood vessels should be avoided. After the needle is inserted, no blood should be pumped back before the drug can be pushed to prevent the test solution from directly entering the blood vessel and causing a strong reaction.
Generally, after the whole group of antigen skin test is completed, an intradermal control test should be performed on the adjacent site with physiological saline or antigen-extracting solvent to eliminate the possibility of non-specific stimulation causing false positive reaction, and 0.1 mg/ml is also used. The histamine phosphate solution is used as a positive control test to rule out possible false-negative reactions. In the winter, when the patient performs a skin test, it should be kept warm to prevent the patient from catching a cold.
When performing intradermal tests on patients in the allergic clinic, a large number of tuberculin syringes are required every day. The barrel and core of each syringe should be numbered. The cleaning should be carried out one by one to avoid the tube and the core can not be paired. The liquid leakage or the core cannot be inserted into the bobbin.
5 conjunctival test: Due to the abundant and well-arranged capillary network on the bulbar conjunctiva and the conjunctiva of the eye, the background of the conjunctiva is extremely bright and clean, which is a good place to observe the antigen-antibody reaction. Moreover, the reaction is very rapid, so in some cases, the allergen-specific test can be performed using the conjunctiva of the eye by first dropping the 1:1000 antigen into the right eye of the patient, and if there is no itching after 5 minutes, Redness, tearing, conjunctival hyperemia, etc., can be used to drop 1 drop of 1:100 antigen, and then observe for 5 min. If there is still no reaction, if necessary, 1 drop of 1:10 antigen can be added. If there is still no reaction, then Is negative, if the antigen appears red, eye itching, tearing, conjunctival hyperemia, more than eyelid edema, it is a positive reaction, can also drop 1 drop of normal saline or antigen extraction solvent in the left eye as a control, which is positive The grading criteria were: mild sclerosis of the sclera and conjunctiva (+); sclera and conjunctival hyperemia, itch (++); sclera and conjunctival red, obvious itching and tearing (+++); ++)There is also a conjunctiva out , Eyelid edema (++++).
The advantage of this method is that the reaction is rapid, the phenomenon is clear and vivid, and the test can be done for allergic liquids. However, the following disadvantages are encountered: all antigens with irritating effects should not be used, and this method can only be performed at a time. Testing of an antigen, such as a variety of antigen tests, is not appropriate.
6 nasal mucosa provocation test: The test can be divided into two types, one is the antigen inhalation test (inhalation test), that is, the antigen is inhaled intranasally to stimulate the symptoms of allergic rhinitis, for nearly 30 years, we Clinically, some patients with a history of hay fever allergies and those with negative intradermal tests have conducted many such tests, and found that more than half of them can induce different degrees of hay fever symptoms. The operation method is: a very small amount of dried pollen After being placed in the patient's nasal cavity, a few minutes later, the patient developed paroxysmal sneezing, watery nose, nasal congestion, nasal itching and other symptoms. The nasal mucosa was pale, edema, and secretions increased. Some patients developed asthma attacks at the same time. A large number of eosinophils can be detected from the patient's nasal secretions or sputum.
This test is vivid and convincing to patients and doctors. The shortcoming is that only one antigen can be tested at a time. The dose of the antigen to be used should be strictly controlled to prevent the occurrence of strong reactions. In such trials, there are those who induce asthma, but after proper treatment, the wheezing is calmed down, and the other is the antigen instillation test. All kinds of inhaled antigen infusions can be intranasally dripped. In order to test its sensitivity, in clinical practice, we have tried some infusion of nasal pollination in pollen infusion, and found that the positive rate is far less than that of dry pollen inhalation, and it can also be used to test antigen soaking. The droplets were placed on a 1.0 cm × 1.0 cm square white filter paper, and then the paper was applied to the lower nasal mucosa of one side of the nasal cavity for excitation, but the reaction intensity was far less obvious than that of the dry pollen.
7 bronchial provocative test: similar to the nasal mucosa challenge test, can be induced by antigen aerosol inhalation, or intra-tracheal instillation with antigen infusion, some people use aerosol inhalation or intratracheal instillation of histamine A non-specific challenge test is performed to determine the responsiveness of the patient's bronchus, but there is still controversy about the method of inhaling or instilling histamine or acetylcholine. It is believed that asthma can be induced even if a normal person inhales or drops the above-mentioned agents. The normal induced dose is different for patients of different ages, genders, and weights. As for the intratracheal inhalation or instillation challenge test of antigen, in recent years, it has received considerable attention from foreign countries, and developed specialized instruments for precise quantitative control. Pulmonary function is measured to determine how sensitive a patient's bronchi is to various specific antigens.
8 iontophoresis test: iontophoresis device is used to ionize the antigen and penetrate into the skin or other superficial tissues of the patient to observe the patient's specific reaction. The prerequisite for this test is that the antigen must be Ionized substances, and first understand whether the antigen is ionized after being ionized or cation-free, in order to select different electrodes for penetration, and also requires antigenic ionization without affecting its antigen titer. Its advantage is that it is painless. However, the operation is more complicated, requires a special set of equipment, and there are more links that may affect the results, so it is difficult to promote, and currently only used for some experimental research.
9 Sublingual test: Because there are abundant blood vessels under the tongue, the mucous membrane is thin. If various foods are used, the inhalation antigen soaking solution or soluble drug is placed under the tongue, and it can be absorbed in a short time to produce corresponding Allergic symptoms, the shortcoming is that the scale between the safe dose and the effective dose is difficult to control; each time only one antigen test can be used; in the food test, the patient should stop eating the same food 24 hours before the test, sublingual test The positive reaction is often not manifested in the sublingual part and is manifested in the system of breathing, digestion, circulation, etc., so it must be carefully observed by experienced testers to determine the number of G.Pfeiffer, the founder of the sublingual test, American allergist. This method has been used clinically for a specific diagnosis of allergic reactions in patients for 10 years.
10 food provocation test: This test is suitable for patients who have a history of allergies to a certain food and have a specific skin test result that is inconsistent with the medical history. In order to further clarify the patient's sensitivity to the food, Try this test by: the patient is forbidden to use this kind of food 24 hours before the test. It is best to fasting or only a small amount of normal diet on the day before the test. Test the pulse, blood pressure, respiration and white blood cell count for the patient before the test. Then let the patient eat suspicious food, the amount of food can be determined according to the condition, for example: those who are allergic to wheat noodles can eat a loaf of bread or steamed bread; those who are allergic to eggs can eat 2 eggs at a time; those who are allergic to milk can drink half a pound of milk at a time Then, the patient was observed in the hospital for about 3 hours. During the period, 0.5, 1.5, and 2.5 hours after the meal, the pulse, breath, blood pressure, and white blood cell count were observed once. The patient was observed to have any respiration, the pulse was significantly increased, and the blood pressure or white blood cell count was decreased. At the same time, observe whether the patient has abdominal pain, nausea, vomiting, rash, itchy skin, diarrhea, headache, sneezing, asthma and other allergic symptoms. 3h100012
(passive transfer test)-(Prausnitz Küstner testPK)24h10ml24h0.1ml2448h
PK××5;
(specific bacterial vaccine test)511000110011015min24h48h2448h(+)(++);(+++)9;
Diagnosis
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