I. Atopic cough
This refers to a cough accompanied by other signs or symptoms that can suggest an atopic cause, i.e., the cough is one of the symptoms of these clearly diagnosed diseases. For example, cough accompanied by expiratory dyspnea, prolonged expiratory phase or croup on auscultation often indicates intrathoracic airway pathology such as tracheobronchitis, asthma, congenital airway developmental abnormalities (e.g. tracheobronchial softening), etc.; accompanied by shortness of breath, hypoxia or cyanosis indicates pulmonary inflammation; accompanied by growth disorders and pestle-like fingers (toes) often indicates severe chronic lung disease and congenital heart disease, etc.; accompanied by Pus sputum suggests pulmonary inflammation and bronchiectasis; hemoptysis suggests severe pulmonary infection, pulmonary vascular disease, pulmonary ferritinosis or bronchiectasis.
Non-specific cough
This refers to chronic cough in which cough is the main or only manifestation and no abnormalities are seen on chest x-ray. This is the main type of chronic cough in clinical practice, also known as “chronic cough in the narrow sense”. The causes of nonspecific cough in children are age-specific and require careful systematic evaluation, thorough history taking, and physical examination [E/A], chest radiography in these children, and pulmonary ventilation in those of appropriate age [E/B].
1. Respiratory infections and post-infectious cough: Respiratory infections caused by many pathogenic microorganisms such as Mycobacterium pertussis, Mycobacterium tuberculosis, viruses (especially respiratory syncytial virus, parainfluenza virus, cytomegalic inclusion virus), Mycoplasma pneumoniae, and Chlamydia are common causes of chronic cough in children, mostly in preschool children <5 years of age.
Acute respiratory infections with cough symptoms lasting more than 4 weeks can be considered post-infectious cough. The mechanism may be disruption of airway epithelial integrity and/or squamification of ciliated columnar epithelial cells and/or persistent airway inflammation with temporary airway hyperresponsiveness as a result of the infection. The clinical features and diagnostic clues of post-infectious cough are.
(1) A recent history of definite respiratory tract infection ;
(2) Cough that is irritatingly dry or with a small amount of white mucous sputum;
(3) No abnormalities on chest x-ray;
(4) normal pulmonary ventilation;
(5) The cough is usually self-limiting;
(6) Other causes of chronic cough are excluded. If the cough lasts longer than 8 weeks, other diagnoses should be considered.
2. Cough variant asthma: CVA is one of the common causes of chronic cough in children, especially in preschool and school-age children.
The clinical features and diagnostic clues of CVA are.
(1) Persistent cough >4 weeks, often with episodes at night and/or early in the morning, aggravated by exercise and cold air, without clinical signs of infection or after a longer period of ineffective antibiotic treatment;
(2) Diagnostic treatment with bronchodilators may result in significant relief of cough symptoms;
(3) Normal pulmonary ventilation and bronchial excitation test suggesting airway hyperresponsiveness;
(4) A history of allergic disease including drug allergy, and a positive family history of allergic disease. A positive allergen test may aid in the diagnosis;
(5) Excluding chronic cough caused by other diseases.
(3) Upper airway cough syndrome: Various rhinitis (allergic and non-allergic), sinusitis, chronic pharyngitis, chronic tonsillitis, nasal polyps, adenoid hypertrophy and other upper airway diseases can cause chronic cough, which was previously diagnosed as postnasal drip (flow) syndrome, meaning that nasal secretions flow backward through the postnasal orifice to the pharynx [cough. The ACPP suggests the name upper airway cough syndrome instead of PNDs .
The clinical features and diagnostic clues of UACS are.
(1) Chronic cough with or without sputum, the cough is worse in the early morning or when the position is changed, often accompanied by nasal congestion, runny nose, dry throat with foreign body sensation, repeated clearing of the throat, and a feeling of mucus adherence to the posterior pharyngeal wall; a few children complain of headache, dizziness, and low-grade fever;
(2) Examination of the sinus area may have pressure pain, there may be yellowish-white discharge from the sinus opening, the posterior pharyngeal wall follicles are obviously hyperplastic, cobblestone-like, and sometimes the posterior pharyngeal wall mucus-like adhesions can be seen;
(3) targeted treatment such as antihistamines and leukotriene receptor antagonists, nasal glucocorticoids are effective; (4) sinusitis caused by the sinuses, sinus x-ray plain film or CT film can be seen corresponding changes.
4, gastroesophageal reflux cough: gastroesophageal reflux (GER) is a physiological phenomenon in infancy and early childhood. The incidence of GER in healthy infants is 40% to 65%, with a peak at 1 to 4 months and more natural relief at 1 year of age. GERD becomes a disease when it causes symptoms and/or is accompanied by gastroesophageal dysfunction, and the prevalence of GER in children is about 15%. The latest study found only 4 cases of GER in 49 children with chronic cough (8,2%), and the results of the study by Zhao Shunying et al. showed that only 1 out of 50 cases of chronic cough was GER, so there is no definite evidence that GER is a common cause of chronic cough in children in China [E/B].
The clinical features and diagnostic clues of GERC are.
(1) Paroxysmal cough with severe cough on the right, mostly occurring at night ;
(2) Symptoms mostly appear after eating and drinking, and feeding is difficult. Some children have epigastric or subxiphoid discomfort, retrosternal burning sensation, chest pain, and sore throat;
(3) In addition to coughing, it can also cause choking, bradycardia and a bowed back in infants;
(4) It can lead to stagnant or delayed growth of the affected children.
5. Eosinophilic bronchitis: EB was first reported by Gibso in 1989, and a recent prospective study revealed that EB accounts for 13,5% of patients with chronic cough in adults. EB is considered to be an important cause of chronic cough in adults, but its incidence in children is unclear [E/B].
Clinical features and diagnostic clues of EB are.
(1) Chronic irritant cough ;
(2) Normal chest radiographs;
(3) Normal pulmonary ventilation without airway hyperresponsiveness;
(4) relative percentage of eosinophils in sputum > 3%; (5) effective oral or inhaled glucocorticoid therapy.
6, congenital respiratory disease: mainly seen in infants and children, especially within 1 year of age. Gormley’s study reported that 75% of children with tracheal softening (second only to congenital vascular malformation) have persistent cough, and the mechanism may be related to tracheal softening obstructing the discharge of secretions and inflammatory damage to the terminal bronchi. The mechanism may be related to the obstruction of secretion drainage by softened airways and inflammatory damage to the terminal bronchi. This condition is often misdiagnosed as asthma.
7. Psychogenic cough: ACCP recommends that psychogenic cough in children should be diagnosed only if tic disorders are excluded and the cough improves after behavioral interventions or psychotherapy; cough features are only suggestive of psychogenic cough, not diagnostic [E/B].
The clinical features and diagnostic clues of psychogenic cough are: (1) it is more common in older children; (2) the cough is predominantly daytime and disappears when focusing on an event or resting at night; (3) it is often accompanied by anxiety symptoms; and (4) it is not accompanied by organic disease and other causes of chronic cough are excluded.
8. Other etiologies.
(1) Foreign body aspiration: coughing is the most common symptom after aspiration of foreign bodies in the airway, and foreign body aspiration is an important cause of chronic cough in children, especially those 1-3 years old. Studies have found that 70% of patients with airway foreign body aspiration present with cough, and other symptoms include decreased breath sounds, wheezing, and history of asphyxia. Once the foreign body enters the area below the small bronchus, there can be no cough, i.e. the so-called “silent zone”.
(2) Drug-induced cough: Angiotensin-converting enzyme inhibitors (ACEl) are less commonly used in children, and some children with renal hypertension may have cough induced by the use of ACEIs such as captopril. The mechanism may be related to the secretion of bradykinin, prostaglandins, and substance P. ACEI-induced cough usually manifests as a chronic persistent dry cough that is aggravated at night or when lying down, and can be significantly reduced or even disappeared by stopping the drug for 3 to 7 d. B-adrenergic receptor blockers such as tretinoin can cause bronchial hyperresponsiveness, so they may also lead to drug-induced cough.
(3) Otogenic cough: 2-4% of the population has an auricular branch of the vagus nerve (arnold nerve). In this group, chronic cough is caused by stimulation of the vagus nerve when the middle ear becomes diseased. Otogenic cough is a rare cause of chronic cough in children.