Overview
Cough is an important defense mechanism that can also occur in normal individuals, clearing secretions and foreign bodies from the airways and stopping the spread of respiratory infections. However, cough is also a common clinical symptom of respiratory diseases and is the most common complaint of illness. Approximately 30% of patients in respiratory clinics are seen for chronic cough of unknown origin. Frequent and severe cough can seriously affect the child’s school and life, and may cause complications in several organ systems, so the management of cough, especially chronic cough, is receiving increasingly high attention.
Coughs can be divided into two categories based on their symptoms and duration characteristics.
Chronic cough in children
The 2006 US chronic cough guidelines: Chronic cough in children lasting >4 weeks Chronic cough in children with persistent or recurrent cough for >4 weeks with no obvious concomitant symptoms No pulmonary signs No abnormalities on chest x-ray Poor outcome of appropriate treatment
Physiology of the cough reflexPhysiological significance of the cough reflex: The coughing action is a very important protective behavior of the human respiratory tract. The respiratory tract is an open organ that expels foreign bodies and secretions from the airways (including above the terminal bronchi) in three ways. These are the clearance function of the ciliated epithelial cells, the peristalsis of the fine bronchi and the cough reflex. When coughing is weak (e.g., coma, neuromuscular disease, etc.) airway secretions cannot be removed by coughing, which can lead to pulmonary atelectasis, etc. The physiological significance of coughing prevents foreign bodies, pathogens, etc. from entering the lower airway Clears foreign bodies and excessive secretions that have already entered the airway Clears respiratory irritants to prevent the spread of infection
Diagnosis and treatment of chronic cough according to the anatomical mechanism of the cough reflex
1. History and physical examination: Focus on the anatomical sites of the cough reflex receptors and efferent branches. Special consideration should be given to the common causes of chronic cough, such as bronchial asthma and cough variant asthma, which are most commonly located in the upper respiratory tract; gastroesophageal reflux and eosinophilic bronchitis should be considered as common causes of extrapulmonary factors
2. Chest X-ray: X-ray examination of all patients with chronic cough is helpful in making a preliminary differential diagnosis. If there is no abnormality in the chest X-ray, postnasal drip syndrome, asthma or cough variant asthma, gastroesophageal reflux, and eosinophilic bronchitis should be considered first.
3. Related tests: Based on the results of the above initial evaluation, the following related tests can be considered. 1) sinus CT radiography; 2) allergen skin test; 3) peak expiratory flow rate (PEF) morning and evening monitoring; 4) induced sputum flow cytology, cytokine and microbiological examination; 5) bronchial diastolic test or excitation test; 6) fiberoptic bronchoscopy (bronchoalveolar lavage, mucosal biopsy); 7) ) esophageal iodine oil or barium angiography; 8) 24-hour pH measurement of the lower esophagus.
4. Diagnostic treatment The etiology of chronic cough is determined by targeting common etiologies or assessing possible pathophysiological mechanisms for specific treatment. For example, when cough variant asthma is suspected diagnostic treatment with bronchodilators (β2 agonists) is available, and if nocturnal or morning cough is significantly better, the diagnosis is basically clear through treatment. Chronic cough in children is classified according to its mechanism of occurrence as respiratory tract infections allergic diseases foreign bodies or other stimuli respiratory tract pressure precursor weather tract malformations cardiovascular system neuropsychiatric factors other
Diagnostic ideas of pediatric chronic cough
Etiology of chronic cough
Infancy and early childhood
Infectious diseases.
1. acute onset and severe toxic symptoms of Staphylococcus aureus, adenovirus pneumonia, etc., with a longer duration of illness and cough.
2. pneumonia caused by atypical microorganisms, mainly Chlamydia and Mycoplasma, often with frequent paroxysmal dry coughs, heavy at night, while the signs are often not obvious and the duration of the disease is generally long.
3. endobronchial tuberculosis, in which enlarged lymph nodes compress the trachea, causing an irritating dry cough, but mostly with symptoms of tuberculosis toxicity, and a clear diagnosis can be made with relevant tests.
4. Infants and children with poor respiratory defenses and repeated respiratory infections are also causes of chronic cough.
Digestive tract diseases
1. gastroesophageal reflux.
2. esophagotracheal fistula Choking and coughing with respiratory distress and asphyxia at each feeding after birth, and the insertion of a gastric tube often folded back due to obstruction, requiring surgical correction.
3. congenital diaphragmatic hernia may have recurrent coughing, prone to respiratory distress, diagnosed by chest X-ray or CT examination, requiring surgery. Congenital malformations Congenital bronchial or pulmonary dysplasia, unilateral pulmonary dysplasia, pulmonary isolation, ciliary dysplasia, and alveolar cystic degeneration are all causes of chronic cough, and chest radiographs, CT, and cilia for dimensional bronchoscopy are helpful for diagnosis.
Preschool and school-age children
Infectious diseases
Chronic pharyngitis Viruses, bacteria, and atypical microorganisms can cause throat infections, and secretion irritation can cause cough and foreign body sensation in the pharynx, which is worse at night and can be accompanied by fever and hoarseness.
In chronic sinusitis, the child has postnasal secretions flowing into the posterior nasal orifice, and the secretions irritate the pharynx and cause a persistent cough. Generally children have chronic runny nose, headache, nasal congestion, open mouth breathing, etc. They may also have low fever, pressure pain in the paranasal sinus area, swelling of the turbinate mucosa, and often accompanied by enlarged tonsils and proliferators.
Rhinitis sinusitis bronchitis disorders can be bacterial infections, viral infections and allergic disorders, mainly rhinitis, sinusitis and bronchitis coexist. The manifestations are nasal congestion, runny nose, (clear or pus), headache, localized pressure, cough, sputum and wheezing.
Tuberculosis chronic cough as the only clinical manifestation pulmonary signs are not obvious may be accompanied by chronic tuberculosis toxicity X-rays without obvious abnormal changes CT: high resolution and enhancement, showing diagnostic sputum, gastric fluid, fibrinoscopy, lavage fluid smear finding antacid bacilli or culture positive for Mycobacterium tuberculosis Primary pulmonary ferritinosis The etiology of this disease is unknown, characterized by recurrent or chronic cough, blood in the sputum or hemoptysis, dyspnea, with significant small The disease is characterized by recurrent or chronic cough, blood in sputum or hemoptysis, dyspnea, and marked microcytic hypochromic anemia, with severe hepatosplenic lymphadenopathy. The diagnosis is supported by the presence of iron-containing hemoglobin particles in sputum and gastric juice, and by the presence of extensive small, dense dot-shaped images in both lungs on chest radiographs.
Bronchiectasis Bronchiectasis is congenital or acquired, manifested by recurrent cough, sputum, hemoptysis, dyspnea, etc. The amount of sputum is related to the position, and pestle finger, different degrees of anemia, malnutrition, etc. can be seen in long-standing cases, and chest X-ray and CT examination can assist in the diagnosis. Multiple twitching is called twitching-obscene syndrome, which mainly manifests as local twitching such as eyebrow squeezing, teeth baring, neck and limb twitching, along with abnormal vocalizations such as dry cough, light cough, cursing obscenities, etc. The symptoms usually disappear during sleep. Mediastinal occupational lesions can compress the trachea and cause chronic coughing, which is aggravated when the position is changed, often accompanied by fever, dyspnea, hepatosplenomegaly, and difficulty in swallowing. Chest x-ray and CT examination can help in the diagnosis.
Less common diseases
Infectious diseases
1. Pertussis and pertussis-like syndrome: cough is prolonged, atypical in small infants and newborns, and may manifest as paroxysmal cyanosis or asphyxia.
2. Parasitic infections Many parasites can cause coughing and wheezing depending on their invasion sites, and in severe cases, asthma-like attacks, and parasites can be found in feces and sputum. Some have increased eosinophilia or anemia, etc.
3, mycobacterial infections Less common, occurring on the basis of systemic diseases, or after long-term use of immunosuppressants, broad-spectrum antibiotics. The most common is Candida albicans, with cough in addition to low-grade fever, shortness of breath, cyanosis, depression, irritability, signs of pneumonia in the lungs, sputum smear or culture can be seen mycobacterial spores and mycelium.
4, eosinophilic pneumonia Metabolic reaction syndrome with pulmonary infiltrates accompanied by increased peripheral blood eosinophils is characteristic. Allergens include parasites, fungi, pollen, food, etc. Low fever, light cough, fatigue, etc. in mild cases, high fever, paroxysmal cough, asthma, etc. in severe cases. Dry wet rales in the lungs and hormone therapy are effective.
Common diseases of chronic cough and specific treatment
1. Postnasal drip sysdrom (PNDs) refers to cough, wheezing and dyspnea caused by nasal secretions dripping to the back of the nose and reaching the throat. It is the second most common cause of chronic cough in children. It is due to stimulation of the afferent nerve branch-receptors located in the upper respiratory tract. Irritants include allergic, non-allergic, post-infectious, environmental, drug-induced, vasomotor rhinitis and sinusitis. Patients often feel “something” flowing backward into the throat and make frequent “clear throat sounds”. In postnasal drip syndrome, mucus or purulent secretions are seen dripping down from the posterior nasal cavity into the pharynx on oropharyngeal examination. When the postnasal drip is cleared, the blockage of the upper airway improves, the cough is relieved, and breathing is facilitated. Treatment with nasal inhaled glucocorticoids in combination with antihistamines and a combination preparation that inhibits nasal mucosal congestion is applied. Exposure to environmental triggers should also be avoided. In vasomotor rhinitis, topical ipratropium may be applied if the above treatment is ineffective. In case of sinusitis, a combination of antimicrobials and antihistamines should be administered for at least 4 weeks.
Postnasal drip syndrome (PNDS) ① With rhinitis, sinusitis and other underlying nasal diseases ② Postnasal drip and/or feeling of mucus attachment in the posterior pharynx, frequent throat clearing ③ Mucus attachment in the posterior wall of the nasopharynx on examination, cobblestone-like view ④ Purulent discharge from the sinus orifice visible on nasopharyngoscopy ⑤ Thickened sinus mucosa, indistinct sinus cavity or dark areas of fluid ⑥ Significant reduction of cough after treatment
2. Cough Variant Asthma (CVA) is the first cause of chronic cough in children. Asthma with chronic cough as its main manifestation, in which cough is the only symptom, without wheezing and without croup, differs from typical asthma with the following characteristics.
1) Persistent or recurrent cough attacks greater than one month, often at night and/or early in the morning, aggravated by exercise, dry cough without or with little sputum, no clinical signs of infection, and ineffective antibiotic therapy.
2） Bronchodilators can relieve coughing episodes (basic diagnostic condition)
3） A personal history of allergy or family history of allergy, and a positive allergen skin test can be used as an auxiliary diagnosis.
4） The airway is hyperreactive and a positive bronchial excitation test can be used as an auxiliary diagnosis
5） No obvious organic changes on X-ray chest examination. Cough variant asthma is essentially an atypical form of bronchial asthma or an early manifestation of asthma. Eventually it can develop into typical bronchial asthma. Treatment of cough variant asthma is in principle the same as anti-asthma treatment. Inhaled or oral β2 agonists or theophylline can provide rapid symptomatic relief. Long-term, continuous and regulated inhaled glucocorticoids can effectively control symptoms and prevent their later development into typical bronchial asthma.
3. Gastroesophageal reflux is one of the common causes of chronic cough. Gastroesophageal reflux leading to cough or even asthma may be due to the following two reasons
1) Chemical airway inflammation: chemical irritation triggering cough or asthma due to aspiration of small or large amounts of gastric contents into the airway.
2) Vagal nerve-mediated bronchoconstriction: the prolonged removal of food from the esophagus due to reflux causes inflammation of the esophageal mucosa, mucosal epithelial erosion and detachment, and exposure of the vagal nerve fibers, which increases the sensitivity of the receptors in the esophagus to the reflux, and the receptors in the esophageal mucosal epithelium are stimulated and send out impulses that cause contraction of the airway smooth muscle through vagal nerve mediation, resulting in cough and/or asthma symptoms. Typical symptoms of gastroesophageal reflux-induced cough and/or asthma: a recurrent burning sensation in the chest in older children, aggravated by lying down or bending over, often with sensations such as sour swallowing or pain on swallowing, which may be relieved by drinking water. Younger children may not clearly express the above primary description, but cough or asthma attacks often occur at night. 24-hour lower esophageal pH monitoring may be performed. A positive result is a pH less than 4 greater than 4% of the time in a 24-hour period and is the gold standard for the diagnosis of gastroesophageal reflux. Treatment of cough and/or asthma due to gastroesophageal reflux. H2-blockers, proton pump inhibitors and gastroprokinetic agents should be used in combination. It is important to emphasize that these combinations only improve the symptoms of reflux itself and do not relieve cough and/or asthma, so inhalation therapy with glucocorticoids and bronchodilators is required. Inhalation of vagal blockers such as ipratropium bromide can also improve symptoms. If inhalation of severe reflux is ineffective with the above medical treatment measures, surgical treatment is required to improve the function of the lower esophagus, including the sphincter, so that reflux does not occur again.
4. Eosinophilic Bronchitis (EB ) The number of eosinophils in the sputum of normal people does not exceed 2.5%. Eosinophilic bronchitis can be diagnosed when the number of eosinophils in sputum is greater than 2.5%. Its incidence is about 13% and it is another major cause of chronic cough. It is due to infiltration of eosinophils, resulting in air conduction inflammation with insignificant airflow obstruction, normal pulmonary function PEF, and no airway hyperemesis. Inhaled glucocorticoid therapy is effective.
Diagnostic criteria for EB
(1) Chronic cough, mostly irritating dry cough, or with a small amount of mucous sputum.
(2) Normal X-ray chest film.
(3) Normal pulmonary ventilation function, negative airway hyperresponsiveness test, and normal PEF inter-day variability rate.
(4) Sputum cytology with eosinophil ratio ≥0.03.
(5) Exclude other eosinophilic diseases. Oral or inhaled glucocorticoids are effective.
Treatment: EB responds well to glucocorticoid therapy and the cough disappears or is significantly reduced after treatment. Bronchodilator therapy is not effective. Treatment is usually with inhaled glucocorticosteroids, beclomethasone dipropionate (250-500 μg per dose) or equivalent doses of other glucocorticosteroids, twice daily for more than 4 weeks. Dry powder inhalers are recommended. Initial treatment can be combined with prednisone orally at 10-20 mg per day for 3-7 d.
The relationship and similarities with atopic cough, EB, and post-cold cough need to be further clarified.
2) Clinical manifestations: irritating dry cough, mostly paroxysmal, daytime or nighttime, easily induced by fumes, dust, cold air, speech, etc., often accompanied by itching of the throat. Ventilation is normal, and the percentage of eosinophils in induced sputum cytology is not high.
3) Diagnostic criteria: There are no universally accepted criteria, but the following criteria are for reference.
Allergic cough (atopic cough)
(1) Chronic cough.
(2) Normal pulmonary ventilation and negative airway hyperresponsiveness test.
(3) One of the following indications: (i) history of exposure to allergic substances; (ii) positive SPT; (iii) increased serum total IgE or specific IgE; (iv) increased cough sensitivity.
(4) Exclude other causes of chronic cough such as CVA, EB, and PNDs.
(5) Antihistamine and/or glucocorticoid therapy is effective.
Treatment:Antihistamine medication is effective, and inhaled or short-term (3~7d) oral glucocorticoids are added if necessary.
6. Chronic cough after upper sensation: Most often seen in 5-year-old, bright and articulate children, often accompanied by other symptoms in the somatic area. Classmates, teachers, parents, etc. are disturbed by their frequent coughs, and parents in particular often go to many hospitals to seek medical attention for their coughs, which in turn aggravate their coughs and form a vicious circle.
8. Other In identifying the cause of chronic cough, attention should also be paid to excluding chronic bronchitis, whooping cough, pulmonary tuberculosis, bronchiectasis, etc.
In conclusion, chronic cough is one of the most common problems faced by clinicians. Its clinical diagnosis relies mainly on the history, symptoms, signs and positive findings of ancillary tests. The etiologic diagnosis can only be made after specific examination and treatment for a particular etiology and disappearance or significant reduction of cough symptoms, as the expected positive value of various symptoms in adults is only about 55%.