dust mite allergic asthma
Introduction
Introduction to dust mite allergic asthma Dust mites are important allergens for bronchial asthma. In recent years, a large number of studies have confirmed that dust mites are closely related to bronchial asthma. A recent 13-year follow-up survey of asthmatic children in New Zealand confirmed dust mites as an independent danger. Sensitization factors have a serious impact on the incidence of asthma. In recent years, three surveys in the United States have confirmed that dust mites and cat hair and mites are important predisposing factors for bronchial asthma. Hundreds of studies have confirmed the dust mites and There is a close relationship between bronchial asthma attacks. Therefore, in recent years, the name and concept of the diagnosis of dust mite allergic asthma have been proposed. Since 1987, several international seminars on the relationship between dust mite allergies and bronchial asthma have been held. A large number of basic and clinical research progress on dust mite allergic asthma provides a large number of theoretical basis and specific prevention measures for the prevention and treatment of the disease. basic knowledge The proportion of sickness: 0.0044% Susceptible people: no specific people Mode of infection: non-infectious Complications: pneumothorax mediastinal emphysema
Cause
Dust mites allergic asthma cause
Causes
Mite is a foot-footed animal, arachnid, Ayurveda, and Polygonaceae. There are more than 5,000 species. The dust mites are small in size. The mites are oval in shape and are about 300m long. The eggs are white and the length is about 140m. Among them, the main cause of allergic asthma is Pyrogitphidae, which usually accounts for more than 90% of the total number of indoor ticks. It has been confirmed that there are 47 species of epidermis, of which more than 10 have been in indoor dust. Among them, 6 of them are considered to be most closely related to allergic asthma. These six species are Dermatophagoides pteronyssinus (Der.p), Dermatophagoides farinae (Der.f), and micro-horn dust mites. (Dermatophagoides farinae, Der.f), buried in dust mites (Euroglyphusmaynei, Em), Lepidoglyphus destructor (Lep.f) and Hirstia, which is a dust mite allergic asthma The most important allergen, this section focuses on house dust mites and their allergic asthma.
The shape and living habits of house dust mites:
Pyroglyphid is the main house dust mites, accounting for more than 90%. It is the dominant species in house dust mites. The rest is warehousing, which differs from other mites in terms of form, life and habits.
(1) Morphology and lifespan: The body of the house dust mite adult is oval, small in size, about 200-300m long, brown under the microscope, 8 feet, house dust mite is egg-born, divided into eggs, larvae, first nymph The third nymph and adult larvae are in the growth period of 60% of the time, which is the relative quiescent period of the first nymph. This determines the survival ability of the dust mites under harsh conditions. When the conditions such as temperature and humidity are suitable, they develop from eggs to Adults take about 3 weeks, male dust mites have a survival period of 2 to 3 months, and female dust mites have a survival period of 3 to 5 months.
(2) Living habits: Temperature and humidity are the two main factors affecting the survival of dust mites. Therefore, the clinical control work often starts with indoor temperature and humidity. The temperature is below 0 °C for 24 h, and dust mites can not survive; 0~ Although it can survive at 7 °C but has no ability to reproduce; 1730°C is the optimum temperature for dust mite survival and reproduction; when it is above 35°C, dust mites can die, and air humidity also has an important influence on the survival of dust mites, relative humidity 75% 80% is the optimum humidity for the growth and reproduction of dust mites; when the relative humidity is above 85%, the dust mites cannot multiply; when the relative humidity is less than 70%, the time for the development of the eggs to adult worms is extended to about 5 weeks. Water dehydration leads to dehydration; when the relative humidity drops below 50%, it can cause death of adult mites. Studies have confirmed that the water in the sputum body accounts for about 80% of its body weight, and the body water ratio drops below 50%, which can lead to death. Habits determine that dust mites are suitable for living in warm and humid regions and seasons. In northern China, the breeding season of house dust mites is mainly from June to October. In many areas of southern China, dust mites can multiply all year round, and allergicity in coastal areas. Asthma and house dust mites Sensitively related, house dust mites are mainly used as human or animal dander dandruff. Therefore, dust mites can be propagated quickly in bed dust and bedroom carpets. House dust mites can often be collected when bed dust is sampled, but it is difficult to mass. Collecting, dust mites use various kinds of grain dust as the main food, which is easy to be cultivated and propagated in large quantities. Since clinical research has confirmed that house dust mites and dust mites have the same antigenicity, various dust mites are used for clinical diagnosis and treatment. Infusion preparations are often replaced with dust mites.
The temperature, humidity and food source on the bed are suitable for the growth and reproduction of house dust mites. A person can produce about 0.7g of dander every day, so that the dust mites on the bed have enough food sources, so the dust in the bedding usually contains More dust mites, which may be one of the important causes of bronchial asthma caused by dust mite allergies at night, the study confirmed that in the bed dust of bronchial asthma patients confirmed by dust mites-specific IgE in the body by immunoassay, It usually contains a considerable amount of house dust mites, and although about 50% of the dust mites have died, they are still highly antigenic.
The antigenicity of house dust mites:
Through the antigenic and molecular studies of house dust mites, we can further understand the human immune response to dust mites, and thus develop a more specific immunodiagnosis and immunotherapy program using recombinant allergens or synthetic peptides. Therefore, since the mid-1960s, research on the antigenicity of house dust mites has been carried out, and it has been confirmed that house dust mites have strong antigenicity. Since Voorhorst et al. in 1964, dust mites were first proposed as a major allergen causing human allergy. Since then, it has been confirmed that the antigenicity of dust mites comes from any state and part of it, including live mites, corpses, cockroaches excretions and secretions, carcass decomposition fragments, etc., and excretion and secretions of cockroaches include eggs. Fecal, sputum and lateral oil gland secretions have been shown to present high levels of dust mite-specific IgE in many house dust-induced allergic asthma patients, and the antigenicity of house dust is closely related to dust mites. Dust mites are the main antigenic components in indoor dust allergens. The house dust contains a large number of live mites, corpses and excretion secretions. It has been confirmed in the early 1970s that asthma patients are allergic to room dust. At the same time, it was also allergic to dust mites. Since then, it has been confirmed that about 70% of patients who are allergic to room dust have specific dust-specific IgE or IgG, IgA antibodies, and dust from patients with dust mite allergic asthma. The dust mite bronchus stimulation test found that patients who are allergic to dust mites are often also allergic to room dust, suggesting that there is a close antigenic correlation between house dust and dust mites, related to house dust mites, dust mites, micro-horn dust mites, The antigen-related studies between the scales of eosinophils, burial dust mites and polychaetes have also initially confirmed that there is a certain antigenic relationship between the six species.
Since the 1980s, in order to thoroughly understand the antigenic components of dust mites, many allergic laboratories have collaborated with clinicians to conduct in-depth research through chromatography, separation, recombination, monoclonal antibody technology, etc. of dust mites. Methods, a plurality of purified antigens have been purified from dust mite infusions such as house dust mite, dust mite, micro-dust dust mite, scorpion venom and scorpion dust, and the antigenicity of these purified antigens is significantly different between groups. They are independent purified antigen components, and their molecular weight, isoelectric point, amino acid sequence and surface antigenic determinants are significantly different. The physiochemical properties of these antigens are shown in Table 1, and the statistical data are relatively small.
cP=cysteine protease sP=serine protease
(1) DerI group antigen: This group includes four purified antigens: Der pI, Der fI, Dm I and EmI. The main component of this group of antigens is a glycoprotein with a molecular weight of 25000. When it is extremely unstable, its isoelectric point has Heterogeneity, the structure of this group of antigens is similar, there are very similar amino termini and common antigenic determinants, and the order of the amino terminus is also basically clarified. It is confirmed by studies combining human IgE and IgG. There are cross-antigenicity among the three antigens, 81% of which are homologous. Only 40% to 50% of the antigens in this group can bind IgE antibodies, so many researchers do not think that this group of antigens is dust mites. The main component of the liquid, but clinical studies have found that 80% of asthmatic patients with allergies to dust mite have IgE antibodies against Der pI, suggesting that this group of antigens may be very important. These contradictory results require further study. .
(2) DerII group antigen: This group of purified antigen was purified in the mid-1980s, and there are two kinds of Der pII and Der fII. The isoelectric point is heterogeneous. The two antigens have almost the same amino terminus and cross antigen. Sexuality, 88% of which are homologous. Studies have confirmed that all components of Der pII antigen can bind to monoclonal antibodies or IgE. Der fII has good immunoreactivity, including skin test response, histamine release reaction, etc. The authors believe that this group of antigens is the main antigenic component of dust mites, and clinical studies have confirmed that more than 90% of patients with dust mite allergic asthma have specific IgE for the DerII group.
(3) DerIII group antigen: This group of purified antigens has been purified in recent years, its molecular weight is 29,000 to 30,000, and monoclonal antibodies against DerIII have also been produced. Clinical studies have confirmed that only 16% of patients with dust mite allergic asthma have serum. There are IgE antibodies against the DerIII group, suggesting that this group of purified antigens may not be the main antigenic component of dust mites.
In addition to the above three groups of common purified antigens, in recent years, 11 purified antigens have been purified from Der p, and 8 purified antigens have been purified from Der f. The latest study on the antigenicity of dust mites is to extract antigens from several dust mites. Separation of specific T lymphocyte clones and evidence of T lymphocyte activation and release of cytokines. In these reactions, the reaction with Der p I and Der pII was more pronounced, and several groups of dust mite were used to purify allergens. Studies on human leukocyte antigens (HLA) are also underway, and these studies are important for further elucidating the antigenicity of dust mites and elucidating the mechanisms by which dust mite allergic asthma occurs.
Research status of dust mite allergen infusion preparation:
Dust mites allergen extracts are not only the reagents for the diagnosis and epidemiological investigation of dust mite allergic asthma, but also the main drugs for allergen immunotherapy. Since the 1970s, allergic laboratories around the world A lot of research and improvement have been done on the purification and standardization of dust mite allergen infusion preparations. In the past 10 years, the International Union of Immunization (IUIS) Allergen Standardization Committee has formulated the standardization of dust mite allergen infusion. Many standards have been used in many laboratories to use the monoclonal antibodies of the Der p and Der f groups for the purification of dust mites antigens, the localization of antigenic determinants, and the development of qualitative and quantitative immunoassays for antigens in dust mite allergens. Great progress has been made in the standardization and purification of liquid preparations. Various laboratories have developed a number of standards for dust mite allergen infusion preparations by radioimmunoassay, radioimmunoassay, and rocket immunoelectrophoresis. Physical and immunological indicators, and according to this standard, a variety of dust mite purified antigen preparations are produced, and the types of these purified preparations and other non-purified preparations are related. Content.
At present, there are more than 1000 kinds of allergen infusion preparations for clinical use, including hundreds of purified antigen preparations. Among them, the most ideal preparation of dust mite allergen infusion purification preparation should be standardized in IUIS allergen. Prepared under the guidance of the Committee, approved by the WHO (NTBSC Pharmacopoeia 82/518), an international standard Dp extract, which is a lyophilized preparation containing 12.5 g of Der PI purified antigen per ampule, Der PII purified antigen 0.4 Gg, with a strength of 100,000 IU, is also commonly used by the US Food and Drug Administration (FDA) approved allergen standard preparations, such as FDAE-1-Dp preparation containing 46 g of Der P I and 25 g of Der P per ml II, FDAE-1-Df preparation contains 3.5g of Der f I and 16g of Der f II per ml. The above-mentioned several dust mite allergen preparations have become commonly used commercial medicines for dust mite allergic asthma. Diagnosis and treatment provide standard purified antigen preparations with high potency and few side effects.
Pathogenesis
Airway allergic inflammation (35%):
Airway allergic inflammation induced by dust mite allergies is the main pathological change of dust mite allergic asthma. After dust mite allergic asthma patients undergo dust mite allergen bronchial challenge test, peripheral blood-specific IgE, leukocyte-mediated The increase in the level of eosinophil cationic protein (ECP) in the hormone-2 receptor and bronchoalveolar lavage fluid suggests that dust mites can activate T lymphocytes and eosinophils in the airways, inhaling dust mites allergic asthma patients. At the same time as airway hyperresponsiveness or delayed phase asthma reaction after dust mite allergen infusion, ECP levels, leukotriene concentration and eosinophil count were increased in bronchoalveolar lavage fluid, due to clinical routine The airway hyperresponsiveness, late-onset asthmatic response, and elevated ECP levels and eosinophil counts in the airway after the allergen challenge test were used as important indicators for judging the presence of airway allergic inflammation, thus suggesting dust mite induction. Airway inflammation is the leading cause of dust mite allergic asthma.
(1) Dust mites can induce airway hyperresponsiveness: related studies have shown that when dust mite allergic asthma patients inhale a certain concentration of dust mite allergen immersion liquid for the challenge test, even if the inhalation is lower than the normal population up to several Multiple or even hundreds of times the concentration can also induce specific airway hyperresponsiveness. Other studies have also found that patients with dust mite infusion skin test positive and serum dust mite-specific IgE-positive non-asthmatic atopic physique, The airway responsiveness is significantly higher than that of non-atopic traits, suggesting that the mechanism of dust mites-induced allergic asthma may be related to airway hyperresponsiveness caused by dust mite-induced airway allergic inflammation.
(2) Dust mites can induce delayed-onset asthma response: Studies have shown that bronchial provocation tests of dust mite allergen infusion can not only induce rapid-onset asthmatic reactions, but also induce delayed-onset asthmatic reactions due to late-onset asthmatic responses It is closely related to airway allergic inflammation and airway hyperresponsiveness. Therefore, it is important to study the late-onset asthmatic response caused by dust mites to explore the mechanism of airway allergic inflammation in allergic asthma. The authors have suggested that the improvement of the late-onset asthmatic response after the dust mite allergen infusion bronchial provocation test can be used as the main indicator for the improvement of the dust mite allergic asthma.
(3) Dust mites can induce an increase in inflammatory cells and inflammatory mediators in the airways: Van et al (1995) have shown that inhalation of dust mite allergen infusion can induce an increase in eosinophil counts in bronchoalveolar lavage fluid, ECP and Increased levels of LTs suggest that dust mites can participate in the regulation of airway inflammation by activating eosinophils.
Indoor dust mites have a high density (25%):
Indoor dust mites are closely related to dust mite allergic asthma attacks. The higher the density, the more likely it is to induce asthma. Studies have shown that patients living in rooms with high dust mites in the room, regardless of the number of asthma attacks or the severity of asthma attacks The aspect is significantly higher than the number of patients living in indoor dust mites. The study by Lau et al. confirmed that the incidence of dust mite allergic asthma in children living in high-density dust mites is the living in low-density dust mites. 7 to 32 times, the mean value of serum dust mite-specific IgE levels in the former is also significantly higher than the latter. The number of episodes of asthma in the former is also significantly higher than that in the latter. Therefore, controlling the dust mite density in the room is the prevention and control of dust mite allergic asthma. The key link.
Correct evaluation of the density of house dust mites has important guiding significance for the prevention, diagnosis, treatment and prognosis of dust mite allergic asthma. There are three methods for evaluating indoor dust mites: 1 Dust mites count: per gram by microscopy The number of dust mites contained in the room dust; 2 Determination of the micrograms of the Der I group of allergens contained in the immersion liquid extracted per gram of room dust: determined by the commonly used ELISA method, but since the method only measures the deformation of the Der group Originally, it is unclear whether it can reflect the true condition of the allergen in the room dust. 3 Determination of guanine: Determine the content of guanine in the immersion liquid extracted per gram of room dust and estimate the indoor dust mites density. For scientific research, the above three methods for assessing indoor dust mites have good correlations.
With regard to the extent to which indoor dust mites can cause sensitization or acute asthma attacks, how can the density of dust mites in the room be reduced to avoid or avoid the symptoms of asthma? Under the guidance of WHO in 1992, The second international meeting of dust mite allergies and bronchial asthma in the United Kingdom set the interim evaluation criteria:
(1) Dust threshold concentration sufficient to cause sensitization in patients: Most scholars believe that each gram of chamber dust contains 2 g of allergens in the DerI group (or when there are about 100 dust mites per gram of room dust, or per gram of room dust) The guanines up to 0.6mg) are sufficient to cause the atopic quality of the patient to be sensitized to the dust mites, and the patient's airway is in a high reaction state. At this time, the patient's serum dust mites-specific IgE is positive, and the patient is in asthma. The incubation period of the attack.
(2) Indoor dust mites concentration in acute exacerbation of patients with dust mite allergic asthma: when the ash per gram chamber contains the DerI group allergen > 10 g (or the number of dust mites per gram of room dust > 500 or per gram of room dust) When the guanine content is >2.5 g, it has a high risk of sensitization and is sufficient to induce an acute attack or a heavier clinical symptom of an asthma patient who is allergic to dust mites.
(3) Relative safe concentration: The symptoms of the dust mite allergic asthma patients can be significantly improved by some measures to reduce the allergen content of the DerI group per gram of room dust to less than 2 g.
Any standard can only be suitable for most patients, because each patient has a large difference in sensitivity to dust mites, such as patients with high airway responsiveness or strong serum sputum-specific IgE, exposure to low-density dust can also have more obvious symptoms, and patients with slightly higher airway responsiveness or weaker serum sputum-specific IgE may have no symptoms when the indoor dust mites concentration is >500/g.
Age (10%):
Most studies suggest that the proportion of dust mite allergic asthma in children and adolescents is significantly higher than that of middle-aged and elderly people. With age, the proportion of dust mite allergies can be reduced year by year. The vast majority of dust mite allergic asthma patients are From the younger age, but some studies have shown that the transfer of non-asthmatic patients with atopic quality to areas or rooms with high-density dust mites can also cause sensitization episodes. It is generally believed that early childhood is the main age of dust mites. A prospective study in recent years has confirmed that infants within 6 months of birth usually have a low allergic rate to dust mites, which may be related to the sensitization of infants and young children at this time, or may be due to beds that infants are exposed to during this period. The bedding is made of new materials and is often cleaned. However, the prevalence of skin test for dust mites and the incidence of dust mite allergic asthma in children aged 6 months to 2 years after birth are significantly increased, living in dust mites. This is especially true for children in higher areas, where statistics on the incidence of dust mite allergic asthma in different age groups are relatively small.
Prevention
Dust mites allergic asthma prevention
The main cause of dust mite allergic asthma is dust mites, so the patient's exposure to dust mites is the main measure to prevent the disease, although the most effective way to eliminate dust mites and measures to avoid dust mites have not yet been determined, but Some methods have been found to reduce the density of dust mites in the house, mainly including the following two aspects.
1. Control the growth of dust mites, reduce the density of house dust mites and avoid contact with dust mites to prevent the effects of dust mites allergic asthma. It can be confirmed by the complete relief of symptoms after the patient lives in a flawless environment. Studies have confirmed that patients with dust mite allergic asthma live in innocent rooms, and one week after the dust mite contact is completely avoided, the patient's airway hyperresponsiveness is significantly reduced, the condition is completely relieved, and the contact is continued for one month. High reactivity can return to normal or near normal levels. Therefore, for patients diagnosed with dust mite allergic asthma, avoiding dust mites is the most fundamental and effective measure. Doctors can consult, write materials or slides. Educating patients to learn various measures to reduce the density of indoor dust mites and ways to avoid contact. In recent years, some countries have used computers to educate and prevent dust mites and achieve better results. The main purpose of educating patients is to teach Avoid or reduce the concentration of dust mites in the room to a non-clinical level by various effective measures Asthma attacks, how to reduce indoor dust mites to a level that is not clinically significant (ie, less than 100 dust mites per gram of room), several controlled trials have shown that simple general hygiene methods cannot be used This request, the report of the last two International Conference on Dust Mites Allergy and Asthma, believes that the following measures should be taken:
(1) Bedroom, bedding treatment: the dust in the bedroom, especially the dust in the bedding, is the most important for cleaning. The measures include removing all the dusty items in the bedroom, cleaning the bedroom regularly and ventilation every day. The bedding that can be washed, such as bedspreads, sheets, quilt covers and pillowcases, is washed and scalded for at least 2 weeks. The articles washed in hot water above 55 °C for 10 minutes can kill dust mites, heat at 100 °C. Water not only kills live mites, but also denatures all allergens related to dust mites, and reduces antigenicity. Studies have shown that washing with cold water can only wash away some dust mites, can not kill, and the effect of mites is not ideal. Beds that are difficult to clean such as pillow cores, quilts, mattresses, etc. should always be exposed to sunlight, tapping, and in winter, these beddings can be placed outside the cold below 0 °C, and can also kill dust mites, if the economy Conditions permit, bedding and other bedding should be replaced once every 2 to 5 years, hot water mattresses, foam mattresses can be used instead of ordinary mattresses. In recent years, Owen et al. used dense textiles made of Venflex material as mattresses. Hood, quilt and This combination of Venflex textiles prevents all particles from penetrating, with a single bed and cleaning measures. After 12 weeks of clinical observation, the content of dust mites per gram of dust in the bedding package using Venflex material is confirmed. It is only 1% of the normal control group, suggesting that the use of Venflex material can greatly reduce the dust mites in the dust. The mattress is also very effective with Zippered plastic. The pillow has been promoted and has good preventive effect, if it is before the package. If there is dust mites in the mattress and pillow, it should be replaced. The Zippeded plastic should be regularly inspected for damage. The above two methods are effective methods to control the density of dust mites and avoid contact. A study also confirmed that the use of electric blankets can reduce the humidity of the bed by 24%, and after 3 months of use, the dust mites in the mites can be reduced by about 30%.
Cleaning of other parts of the bedroom can be done by physical means such as regular vacuuming, which is necessary to prevent the accumulation of allergens on furniture, decorations and carpet surfaces, but it is difficult to significantly reduce the number of live animals, Woodfok et al. (1993) compared The removal effect of the nine vacuum cleaners confirmed that the HEPA vacuum cleaner has the best effect. It is not advisable to use carpet in the bedroom. In the cold winter, you can also put the dusty items such as sofas and carpets outdoors, using cold and dry. Kill the dust mites.
(2) Cleaning of other rooms: Although the bedroom is the main breeding ground for house dust mites, the carpet in the living room and the sofa should be vacuumed 1 or 2 times a week. The carpet can also be treated with acaricide. Studies have confirmed that removing carpets from bedrooms and other rooms can significantly improve the symptoms of dust mite allergic asthma and reduce airway hyperresponsiveness in patients.
(3) Control the humidity of the room: Some investigations have confirmed that reducing the humidity of the room is the main method to control dust mites. Most studies believe that when the indoor absolute humidity is >7g/kg, it can cause a large number of dust mites, a study shows that In the winter, when the indoor absolute humidity rises to 7g/Kg, the indoor dust mites concentration also increases. At this time, if the outdoor humidity is below 5g/kg, it is very effective to pay attention to indoor ventilation, but in some areas, outdoor humidity >7g/Kg, when the ventilation is invalid, the dehumidifier should be used to reduce the indoor humidity. Of course, the unreasonable design of the house is the main reason for the increase of the humidity in the living room. For example, poor indoor ventilation can make the indoor relative humidity significantly higher than the outdoor, the ground. Improper moisture barriers can cause the ground to seep and make the carpet wet. The high humidity of the micro-environment in the carpet can promote the growth of dust mites. The local heating method should reduce the amount of dust mites in the carpet by 40% to 80%. A "healthy" residential project using a good mechanical ventilation system has achieved good results in preventing indoor dust mites.
(4) Application of acaricide: Acaricide is mainly used to kill dust mites in carpets. There are many chemical acaricides available in foreign markets.
Although the killing effects of these acaricides are different, they can significantly reduce the amount of dust mites in indoor dust, carpets or mattresses. Currently, they are mainly used in the United States, Europe and other countries, but the final effect of acaricides. There is still much controversy, which may have a lot to do with the method used. Most acaricides are difficult to use for decorative furniture such as sofas, bedding, and the method of use, whether it is spray effective or solution, the powder is effective yet It is clear that the penetration of various drugs on carpets and mattresses is poorly understood. No matter which preparations and methods are used, they should be reused once every 1 to 2 months.
Clinical studies have shown that correct bedroom and bedding disposal methods, effective control of indoor humidity and proper application of acaricide can reduce indoor dust mites by more than 10 times. Research also suggests that reasonable housing design and building structure It is very important to establish corresponding building regulations to prevent indoor dust mites from being a long-term plan to control dust mites.
2. Drug-induced prevention: drug-induced prevention is an important part of the prevention and control of dust mite allergic asthma. Under the premise of ensuring no obvious side effects of drugs, prophylactic treatment by appropriate and active use of certain drugs can often avoid most dust. A sputum-induced asthma attack.
Pre-dusting allergic asthma drugs mainly include mast cell membrane stabilizers and immunotherapy. The former includes sodium cromoglycate, nidocolomi sodium and trinista, which can inhibit airway allergic inflammation induced by dust mites. In order to prevent the onset of asthma, such drugs are usually used 3 weeks in advance to obtain a satisfactory preventive effect. Immunotherapy mainly refers to the desensitization treatment of dust mite allergen infusion, which is generally prevented after 3 months of application. In addition to the above two types of drugs, anti-allergic drugs such as ketotifen can also be used for the prevention of dust mite allergic asthma, and the curative effect is ideal. It can be synergistic with drugs such as sodium cromoglycate or immunotherapy.
Complication
Dust mites allergic asthma complications Complications Pneumothorax mediastinal emphysema
Combined with pneumothorax or mediastinal emphysema, severe cases can be complicated by heart failure.
Symptom
Dust mites allergic asthma symptoms Common symptoms Wind squat sitting breathing wheezing chest tightness nasal itching nose flaps fanatic cough irritability restless breath sounds weakened
Onset or urgency, infants and young children often have symptoms of upper respiratory tract allergies 1 to 2 days before the onset of asthma, including nasal itching, sneezing, sputum, sputum, sputum, etc. and gradually appear cough, wheezing, year The onset of a child is often sudden, often starting with a cough, followed by wheezing and difficulty breathing.
1. Symptoms and signs during acute attacks: The main symptoms of acute asthma attack are cough, cough or snoring, wheezing, difficulty breathing, chest tightness, etc. The typical manifestation is episodes of expiratory breathing with wheezing. Most cases with episodes of cough and chest tightness are mild manifestations. The children are irritated and restless during severe attacks. They sit and breathe, shrug their shoulders, wheezing, pale, nose flapping, lips and nails bruising, sweating all over the body, words when speaking. Can not be continuous, "three concave sign" is obvious, abnormal chest and abdomen movement, thoracic bulging, percussion has been unvoiced, exhalation prolonged, most have a wide range of expiratory wheezing sounds, such as severe airway obstruction, breath sounds can Significantly weakened, wheezing sounds weakened or even disappeared, heart rate increased, there may be signs of jugular vein engorgement, odd pulse and other signs, severe cases may be complicated by heart failure, resulting in extensive lung base, small blisters, liver enlargement and edema, etc. Acute asthma symptoms can be relieved or relieved by treatment with bronchodilators over a period of hours to days.
2. Symptoms and signs of intermittent seizures: Most of the symptoms and signs disappeared in the intermittent period. Some patients had conscious chest discomfort and discomfort. The lungs auscultated breathing sounds weakened, but there was often no wheezing.
Examine
Dust mites allergic asthma examination
1. Serum specificity: IgE>40U/ml (or >4ng/ml) can be judged as a positive reaction, when >200U/ml (or >20ng/ml) can be judged as a strong positive reaction.
2. Serum dust mite specificity: IgG, IgA determination Determination of dust mite-specific IgG also has important reference value for the diagnosis of dust mite allergic asthma.
3. Skin prick test: It is more commonly used. It is generally considered to be tested with a dust mite infusion preparation containing 20 to 70 days er PI/ml. When the diameter of the wind group is above 5 mm, it can be judged as a positive reaction.
4. Bronchial provocation test: Inhalation of dust mite allergen can simulate the onset of dust mite allergic asthma, and is a more reliable means of detecting this disease.
Diagnosis
Diagnosis and identification of dust mite allergic asthma
Diagnostic criteria
The onset characteristics of asthma include: 1 seizure: sudden onset or exacerbation when encountering predisposing factors; 2 time rhythm: often occurring or aggravating at night and in the morning; 3 seasonality: often occurring or aggravating in autumn and winter; 4 reversibility: antiasthmatic drugs usually relieve symptoms, can have a significant remission period, recognize these characteristics, is conducive to the diagnosis and differential diagnosis of asthma.
The specific immunodiagnostic test not only has important reference value for the diagnosis of dust mite allergic asthma, but also can guide the prevention, immunotherapy and efficacy evaluation of dust mite allergic asthma. The main test methods are as follows.
1. Skin test: Injecting dust mite allergen infusion preparation into the diagnosis and epidemiological investigation of dust mite allergic asthma by skin prick test or intradermal injection test, the method is simple, the price is low, and the safety is large, but The positive standard has not been completely unified. The skin prick test is more commonly used. It is generally considered to be tested with a dust mite infusion preparation containing 20 to 70 days er PI/ml. When the diameter of the wind group is above 5 mm, it can be judged as a positive reaction. Dust mites-specific IgE antibodies are often detected in the serum of the subjects, and the repeatability is high. Currently, the commonly used dust mite allergen preparations determined by w/v method, total nitrogen measurement method and protein nitrogen unit measurement method are commonly used in China. Due to poor accuracy and lack of standardization, it is often not accurate enough for skin tests or other specific tests.
2. Dust mites inhalation bronchus stimulation test: Inhalation of dust mite allergen can simulate the onset of dust mite allergic asthma, is a more reliable means of diagnosis of this disease, in addition to bronchial provocation test, environmental stimulation test is also more common, The environmental challenge test is more reliable. It is compared with the test method using the dust mite allergen infusion preparation by the method of natural contact with dust mites, regardless of the way of contacting the allergen, the quantity, or the form of the antigen. The environmental excitation test is more in line with the natural state, thus greatly improving the credibility of the test. However, it is difficult to standardize the environmental excitation test, and the requirements for environmental specific conditions are strict, which is difficult to be used in routine diagnosis and epidemiological investigation. use.
3. Serological examination:
(1) Determination of serum dust mite-specific IgE: At present, radioimmunoassay (RAST) and enzyme-linked immunosorbent assay (ELISA) are used for detection. For example, Pharmacia & Upjohn's CAP detection system is based on the principle of ELISA. High sensitivity, reproducibility, automatic operation, etc., is a common method for the diagnosis of dust mite allergic asthma. The dust mite antigen used in the determination should be internationally standardized dust mite allergen infusion preparation. Most authors believe that serum specific A positive IgE > 40 U / ml (or > 4 ng / ml) can be judged as a positive reaction, when > 200 U / ml (or > 20 ng / ml) can be judged as a strong positive reaction.
(2) Serum dust mite-specific IgG, IgA determination: Determination of dust mite-specific IgG, IgA also has important reference value for the diagnosis of dust mite allergic asthma, but the positive rate is usually lower than dust mite-specific IgE, so most The author believes that it is not suitable for routine diagnosis, and is currently used in clinical research.
(3) Dust-specific T-lymphocyte detection: At the second International Conference on Dust Mites Allergy and Asthma, five authors reported that dust mite-specific T lymphocytes are similar to murine Th2 cells, whereas T lymphocytes from non-allergic patients are similar to "Th1" cells. These data provide the best evidence of "Th1" and "Th2" cells in the human body. The current detection of dust mite-specific T lymphocytes is still in the foundation. Research phase.
