1.Definition of cough
(1) Cough is one of the most common symptoms of the respiratory system.
(2) Coughing is first a rapid and short inspiration, with the diaphragm falling and the vocal chambers closing rapidly, followed by rapid contraction of the respiratory and abdominal muscles, causing a rapid rise in intrapulmonary pressure; the vocal chambers then suddenly open, with high-pressure airflow ejected from the lungs, impacting on the vocal chambers cracks and resulting in a coughing action with a special sound, and the discharge of secretions or foreign bodies, etc., from the respiratory tract.
2. Pros and cons of coughing
Coughing is a protective respiratory reflex of the body. The cough reflex is effective in removing secretions or foreign bodies from the airways. However, there are also disadvantages to coughing, such as prolonged, frequent and violent coughing that interferes with work and rest, and even causes sore throat, hoarseness and respiratory muscle pain, and violent coughing can lead to respiratory bleeding.
3. Causes of cough
(1) Inhalants: Inhalants are divided into two types: specific and non-specific. The former, such as dust mites, pollen, fungi, animal hair, etc.; non-specific inhalants such as sulfuric acid, sulfur dioxide, chlorine ammonia, etc. The specific inhalants for occupational cough are such as toluene diisocyanate, phthalic anhydride, ethylenediamine, penicillin, protease, amylase, silk, animal dander or excrement, etc. In addition, non-specific ones include formaldehyde and formic acid, etc.
(2) Infection: The formation and onset of cough is associated with recurrent respiratory infections. In patients with cough, specific IgE of bacteria, viruses, mycoplasma, etc. can be present, which can stimulate coughing if the corresponding anti-principles are inhaled. After viral infections, direct damage to the respiratory epithelium can occur, resulting in increased respiratory reactivity. It has been suggested that histamine release from basophils is increased by interferon and IL-1 produced by viral infections. Coughs due to parasites such as roundworms and hookworms can still be seen in rural areas.
(3) Food: Cough attacks due to dietary relations are often seen in cough patients, especially in infants and children who are prone to food allergies, but they gradually decrease with age. The most common foods that cause allergies are fish, shrimp and crabs, eggs, milk, etc.
(4) Climate change: Cough can be triggered when the temperature, humidity, air pressure and/or ions in the air change, so it is more frequent in the cold season or during the autumn and winter climate change.
(5) Mental factors: The patient’s emotions, nervousness, and anger can prompt a cough attack, which is generally believed to be caused by the cerebral cortex and vagal reflexes or hyperventilation.
(6) Exercise: About 70% to 80% of patients with cough induce cough after strenuous exercise, which is called exercise-induced cough, or exercise cough. Clinical manifestations include cough, chest tightness, shortness of breath, and wheezing, and croup can be heard on auscultation. In some patients, although there is no typical asthma manifestation after exercise, bronchospasm can be detected by pulmonary function measurements before and after exercise.
(7) Cough and drugs: Some drugs can cause coughing attacks, such as the ACEI class drug captopril.
4. Classification of cough
(1) Acute cough (<3 weeks).
(2) Subacute cough (3-8 weeks).
(3) Chronic cough (>8 weeks).
5. Diagnosis and differential diagnosis of cough
Since cough is a non-specific symptom of many diseases, clinical diagnosis must be confirmed by detailed medical history, comprehensive physical examination, chest X-ray or CT, airway reactivity measurement, pulmonary function, electrocardiogram, fiberoptic bronchoscopy and some special examinations to exclude other diseases that can cause chronic and persistent cough for diagnosis and differential diagnosis.
6. Principles of cough treatment
(1) Treat the cause.
(2) Symptomatic treatment.
7.Definition of chronic cough
Chronic cough: a cough that lasts for more than 8 weeks and can last for several years or even decades.
8. Etiology of chronic cough
The causes of chronic cough are more complex and commonly include
(1) cough variant asthma (allergic bronchitis)
(2) posterior nasal drip syndrome.
(3) gastroesophageal reflux.
(4) eosinophilic bronchitis.
(5) chronic bronchitis.
(6) Cardiogenic cough.
(7) Drug-induced.
9.Auxiliary examination
(1) Induced sputum examination: It was first used for the diagnosis of bronchial lung cancer, and the positive rate of cancer cell examination can be significantly increased by induced sputum cytology examination, which is even the only diagnostic method for some early lung cancers. Increased eosinophils in cytology examination is the main indicator for the diagnosis of EB.
(2) Imaging X-ray chest radiographs can determine the location, extent and morphology of lung lesions, and even their nature, leading to a preliminary diagnosis and guiding empirical treatment and correlative examinations. X-ray chest radiographs are recommended as a routine examination for chronic cough, and if organic lesions are found, the relevant tests are selected according to the lesion characteristics. x-ray chest radiographs without obvious lesions are examined according to the chronic cough diagnostic procedure (see Chronic Cough Diagnostic Procedure). CT chest examination helps to detect anterior and posterior mediastinal lung lesions, small intrapulmonary nodules, enlarged mediastinal lymph nodes and smaller masses within the marginal lung fields. High-resolution CT is helpful in diagnosing early interstitial lung disease and atypical bronchiectasis
(3) Pulmonary function tests: Ventilation function and bronchodilation tests can help diagnose and identify airway obstructive diseases such as asthma, chronic bronchitis and large airway tumors. Routine lung function is normal, and CVA can be diagnosed by excitation test.
(4) Fiberoptic bronchoscopy (referred to as fiberoptic bronchoscopy): it can effectively diagnose lesions in the tracheal lumen, such as bronchopulmonary cancer, foreign bodies, and endothelia tuberculosis.
(5) Esophageal 24h pH monitoring: It can determine the presence of gastroesophageal reflux (GER), and is the most effective method to diagnose GERC. By dynamically monitoring the change of esophageal pH, six parameters such as the number of times of 24h esophageal pH <4, the longest reflux time, and the percentage of ph <4 to the monitoring time are obtained, and finally the degree of reflux is expressed by demeester score.
(6) Cough sensitivity test: The cough is induced by stimulating the corresponding cough receptors by nebulizing the subject with a certain amount of aerosolized irritant particles, and the number of coughs is used as an indicator of cough sensitivity. Capsaicin inhalation is commonly used for cough provocation tests. Increased cough sensitivity is commonly seen in AC, EB, and GERC.
(7) Other tests: Increased eosinophils in peripheral blood tests suggest parasitic infections, allergic diseases. Allergen skin test (SPT) and serum specific IgE assay can help diagnose allergic diseases and determine the type of allergens.
10.Cough variant asthma (allergic bronchitis)
Cough variant asthma (CVA), also known as cough type asthma, used to be called “allergic bronchitis” or “allergic cough” or “cryptogenic asthma”. CVA, also known as Cough Type Asthma, used to be called “allergic bronchitis” or “allergic cough” or “occult asthma”. The disease was first reported by Gluser in 1972 and named variant asthma. Cough variant asthma is a specific type of asthma in which chronic cough is the main or only clinical manifestation. In the early stages of asthma onset, about 5-6% of cases are characterized by a persistent cough, mostly occurring at night or in the early hours of the morning, often irritating, when it is often misdiagnosed as bronchitis. It has the same pathophysiological changes as asthma and is characterized by a persistent airway inflammatory response with airway hyperresponsiveness.
Reference criteria for the diagnosis of cough variant asthma
(1) Recurrent cough attacks lasting more than 1 month, with a predominantly dry cough; often exacerbated by night and/or early morning attacks or after exercise.
(2) Cough mostly associated with exposure to irritating odors, cold air, exposure to allergens, or excessive exercise.
(3) There may be a history or family history of allergic rhinitis or other allergic diseases, a positive allergen test or increased IgE levels.
(4) Increased airway reactivity.
(5) Antibiotic or allopathic treatment has been ineffective for more than 2 weeks, while anti-allergy treatment or bronchodilators are effective.
(6) Exclusion of chronic cough caused by other chronic respiratory diseases.
11. Auxiliary diagnostic measures
On the basis of detailed medical history, careful physical examination and summary of clinical features, the diagnosis can be confirmed by combining the following methods.
(1) Pulmonary function measurement, if the patient’s FEV1 (ratio of exertional expiratory volume in 1 second to exertional lung volume) or PEFR (peak expiratory flow rate) measured at the time of consultation is lower than 70% of the normal value, the patient can be made to inhale a bronchodilator, such as 2% albuterol 200 μg, and the above indexes are retested 15 minutes later, and if the improvement rate of FEV1 and PEFR is ≥ 15%, the diagnosis of the disease can be confirmed.
(2) If the FEV1 and PEFR are ≥ 70% of the normal expected value at the time of the patient’s visit, a bronchial excitation test may be performed with caution.
(3) Measurement of diurnal variation of PEFR over 24 hours for three consecutive days is a simple and effective screening method to diagnose this type of bronchial asthma, and if the variability of PEFR is ≥20%, the diagnosis of this disease can be confirmed.
Although the measurement of pulmonary function indices is an effective means of early detection of this type of asthma, some studies have found that the frequency of diurnal cough does not correlate with the degree of pulmonary function impairment.
(4) Diagnostic treatment: For patients with clinical suspicion of cough variant asthma, bronchodilators, including inhaled or oral β2-receptor stimulants and theophyllines, can be tried. If the cough is significantly reduced or disappears, the diagnosis of cough variant asthma is supported; if the efficacy is not significant, inhaled glucocorticoids or oral prednisone (30-40 mg/day) can be switched to cough variant asthma, and most cough variant asthma can be Most cough variant asthma can be significantly relieved within one week, and a few patients need to be treated for two weeks before the effect is seen.
12. Treatment
Although cough variant asthma is usually not life-threatening, it should be diagnosed early and treated aggressively because it can develop into classic asthma and because it can seriously affect sleep, work and school.
Once cough variant asthma is diagnosed, antibiotics or antiviral drugs should be stopped and care should be taken to avoid exposure to allergens.
The principles of cough variant asthma treatment are the same as those for typical asthma.
(1) Inhaled glucocorticoids for anti-inflammatory treatment should be the mainstay, and the duration of inhaled glucocorticoids should last for at least 3 months to avoid relapse.
(2) If the cough is severe, the application of bronchodilators such as inhaled or oral β2 receptor stimulants or/and oral theophylline drugs can temporarily relieve the cough symptoms if necessary.
(3) Anti-allergic drugs such as levocetirizine, desloratadine and mast cell stabilizers such as Nedocromil and sodium cromoglycate can also be effective, but often require continuous application for more than 2 weeks.
For patients who have recurrent attacks after stopping medication, allergens should be promptly identified, effective preventive measures should be taken, and allergen vaccine treatment should be given if necessary.
13.Commonly used drugs for cough and phlegm
(1) Drugs acting on the central nervous system, such as morphine (opioid) and codeine.
(2) Drugs acting on the peripheral (terminal) are
(1) Phenylpiperine: non-narcotic cough suppressant, two to four times as effective as codeine. It can inhibit peripheral afferent nerves and also inhibit the cough center. It is taken orally 20-40 mg each time, 3 times a day.
(2) Morgestan: non-narcotic cough suppressant with strong effects. Take 100mg orally 3 times a day.
(3) Narcotine: an isovaline alkaloid contained in opioids, with effects comparable to codeine. Take orally 15~30mg each time, 3~4 times a day. Various kinds of fluid infusion, syrup, etc.
(4) Commonly used phlegmolytic drugs include Bixupine, Ambroxol, Carboxymesterol.