Asthma in pregnancy
Introduction
Introduction to pregnancy with asthma Asthma is a common reversible airway obstructive disease characterized by paroxysmal wheezing, expiratory dyspnea, chest tightness and coughing. Wheezing, especially severe asthma and persistent asthma, not only endangers the mother, but Due to severe hypoxia in the mother, it can cause intrauterine hypoxia, developmental delay, distress, and even fetal death. Therefore, the treatment of asthma attacks during pregnancy is appropriate, directly affecting the safety of mother and child. basic knowledge The proportion of illness: 0.0025% Susceptible population: pregnant women Mode of infection: non-infectious Complications: pneumothorax mediastinal emphysema acute pulmonary heart disease respiratory failure
Cause
Pregnancy with asthma
(1) Causes of the disease
The causes of asthma are complex and are generally dominated by genetic and environmental factors.
1. At present, asthma is considered to be a polygenic genetic disease with a heritability of 70% to 80%. The relevant genes for asthma are not completely clear. Studies have shown that there may be asthma specific genes, IgE regulatory genes and specific immune responses. gene.
2. Environmental factors: including specific allergens or food, infection directly damages the respiratory epithelium, causing increased respiratory responsiveness, certain drugs such as aspirin, etc., air pollution, smoke, exercise, cold air stimulation, mental stimulation and society , family, psychological and other factors can induce asthma.
(two) pathogenesis
The pathological features of bronchial asthma are bronchial smooth muscle contraction, secretion of mucus and bronchial mucosal edema, substances that cause the above changes include histamine, allergic slow acting substances, eosinophil chemotactic factors and platelet activating factors, etc. It is caused by the reaction of allergens, viral infections or nervous movements, which cause inflammatory reactions and make breathing difficult, and at the same time lead to bronchial muscle hypertrophy and increase airway obstruction. Therefore, the current treatment of bronchial asthma, while expanding the bronchus, Great emphasis on reducing inflammation.
One of the most important pathophysiological changes in asthma attacks is that the gas can only be inhaled but not air-trapping. This causes the normal alveolar to over-expand, the alveolar wall capillaries to be compressed, and the proportion of ventilated blood flow to be imbalanced. Oxygen, as the disease progresses further, the amount of functional residual gas in the lung increases, so that the assisted respiratory muscles participate in respiratory exercise. If the condition cannot be improved, eventually the respiratory muscles will be fatigued, and the body manifests as hypercapnia. If the condition is further aggravated, Pulmonary vascular resistance increases with pulmonary hypertension, resulting in a right-to-left shunt.
Hypoxia is the result of dysregulation of ventilated blood flow. PaCO2 is normal or slightly elevated during the initial stage of asthma, but PaCO2 can be increased to 5.33 kPa (40 mmHg) or more after pulmonary hypertension, which is the performance of maternal fatigue. It is suggested that mechanical ventilation should be given early to maintain normal oxygen supply. At the same time, PaO2 of pregnant women decreases when asthma attack occurs. When PaO2 drops to 8.00 kPa (60 mmHg) or below, fetal oxygen saturation may decrease. Hypoxia occurs.
Increased plasma adrenal cortex hormone concentration during pregnancy, increased histidine activity, inhibited immune mechanisms, and reduced inflammation, increased progesterone reduced bronchial tone, reduced airway resistance, plasma cyclic adenosine monophosphate (cAMP) Increased concentration can also inhibit the immune response and relax the bronchial smooth muscle. The increase of prostaglandin E (PGE) concentration in late pregnancy also has the effect of relaxing bronchial smooth muscle. All of the above are beneficial to reduce and relieve asthma attacks, and at the same time, fetal antigen, hyperventilation and The mechanical effects of uterine enlargement are all unfavorable factors that cause asthma.
Mild asthma attacks have little effect on mother and child. Acute severe asthma can be complicated by body failure, progressive hypoxemia, respiratory acidosis, atelectasis, pneumothorax, mediastinal emphysema, pulsus paradoxus, heart failure. And drug allergy, high incidence of pregnancy-induced hypertension, so that the maternal mortality rate is increased, the impact on the fetus is mainly due to hypoxemia and factor blood flow reduction, the fetal weight is low, severe fetal death, hypoxia induced The uterus contracts, so the preterm birth rate is high. In addition, the medication can cause fetal malformation, so the perinatal mortality and morbidity are high.
Prevention
Pregnancy with asthma prevention
1. It is very important to observe the changes of the condition in a timely manner. Once the patient has cough, upper respiratory tract infection, chest pain or pulmonary congestion, preventive treatment should be given to prevent asthma attacks.
2. Avoid contact with known allergens and factors that may promote asthma attacks, such as dust, spices, cut tobacco, cold air, etc., aspirin, food preservatives, bisulfite can induce asthma, should avoid contact, reflux esophagitis can Inducing bronchospasm, so give appropriate antacids before sleep to reduce acid reflux, while improving bedside, reducing caffeine intake, avoiding fatigue and mental stress, and preventing respiratory infections.
3. Immunotherapy can be performed after 3 months of pregnancy, and it is better to treat chronic asthma with influenza vaccine.
Complication
Pregnancy with asthma complications Complications, pneumothorax, mediastinal emphysema, acute pulmonary heart disease, respiratory failure
Acute severe asthma can also occur in pneumothorax, mediastinal emphysema, acute pulmonary heart disease, and even respiratory failure, and death.
Symptom
Pregnancy with asthma symptoms Common symptoms Chest tightness, wheezing, difficulty breathing, wheezing, chest tightness, or belt sensation, pregnancy test positive
Asthma is different in severity. At the beginning of the attack, there may be only a simple cough, which is often missed. There is obvious difficulty in breathing, coughing and wheezing. Due to airway obstruction caused by acute bronchospasm, the patient often has chest tightness and wheezing. Severe hypoxia can occur, physical examination: the patient has hypoxic performance, assisted respiratory muscle movement, exhalation is more obvious than inhalation, auscultation can hear diffuse wheezing, chest over-inflated performance - before and after chest The diameter is increased, the diaphragm is lowered, and the wheezing sound is not proportional to the severity of the disease. When the condition is serious, there is no wheezing due to insufficient airflow.
Examine
Pregnancy with asthma check
In severe cases, arterial blood should be taken for blood gas analysis. The PaO2 of normal pregnant women is similar to that of non-pregnant women, while PaCO2 is reduced from 5.32 kPa (40 mmHg) to 4.1-4.3 kPa (30-32 mmHg) during non-pregnancy due to excessive ventilation. If hypoxemia occurs at the same time as hypercapnia, suggesting that the condition is critical, the normal late pregnancy pH should be 7.42, higher than non-pregnant women 7.35, the identification of respiratory and metabolic properties in the presence of acidosis.
Exogenous asthma patients with elevated blood eosinophils and serum total IgE, sputum contains Charcot-Leyden crystals and mucus plugs composed of eosinophil membrane proteins, neutrophils in the sputum suggest bacterial infection.
Pulmonary function test
The peak expiratory flow rate (PEFR) is measured every morning, evening and before going to bed. If the change of 3 measurements is >20%, or the PEFR value increases by 15%-20% after inhalation of antispasmodic drugs, it is suggested. Bronchial asthma, flow rate <100L/min is severe obstruction.
2. X-ray inspection
In the acute exacerbation of asthma, the lungs are over-inflated and the transparency is increased, and the common lung texture is increased.
Diagnosis
Diagnosis of pregnancy with asthma
diagnosis
According to the history of asthma attacks, physical examination, laboratory tests can make a diagnosis.
Diagnostic criteria:
1. Repeated onset of wheezing, difficulty breathing, chest tightness or cough, and more related to contact with allergens, viral infections, exercise or certain stimuli.
2. At the time of attack, both lungs can smell and diffuse or diffuse wheezing sounds based on the expiratory phase.
3. The above symptoms can be relieved or relieved by treatment.
4. Exclude other diseases that may cause wheezing or difficulty breathing, such as tumor obstruction or compression of the airway, laryngeal edema, endobronchial foreign body, tumor pulmonary embolism, heart failure, etc.
5. For those with atypical symptoms (such as no obvious wheezing or signs), at least one of the following tests should be positive:
(1) If the base FEV1 (or PEF) is <80% normal, the increase is >15% after inhalation of the 2 receptor agonist.
(2) PEF mutation rate (measured by the respiratory peak flow meter, 1 time in the morning and at night) > 20%.
(3) The bronchial provocation test (or exercise challenge test) is positive.
Differential diagnosis
Acute exacerbation of bronchial asthma during pregnancy should be differentiated from cardiogenic heart failure. Left heart failure caused by mitral stenosis is more than dyspnea at night, sitting breathing, coughing, coughing, cyanosis, cyanosis, etc. The lungs can smell wet voices and asthma sounds, the heart expands, the heart rate is fast, and the apex can be heard. According to the corresponding medical history, predisposing factors, the nature of the sputum, the physical examination and the response to the antispasmodic drugs are not difficult to identify.
