I. Definition of chronic cough in children
Cough is the main or only clinical manifestation, with a duration of >4 weeks and no obvious abnormalities on chest x-ray.
B. Etiology of chronic cough in children
(A) Age characteristics should be fully considered in the clinical diagnosis of chronic cough in children, which is an important feature that distinguishes children from adults.
(B) Common causes of chronic cough in children Deng Jianhong, Department of Otolaryngology, Affiliated Hospital of Chengdu University of Traditional Chinese Medicine. Upper airway cough syndrome (UACS): UACS is the first major cause of chronic cough in children, especially in preschool and school-age children. Until 2006, the diagnostic name for UACS was postnasal drainage syndrome (PNDs).
Clinical features and diagnostic clues.
(1) Persistent cough >4 weeks with white foamy sputum (allergic rhinitis) or yellow-green pus sputum (sinusitis), cough worse in the morning or with change of position, accompanied by nasal congestion, runny nose, dry throat with foreign body sensation and repeated clearing of the throat.
(2) marked hyperplasia of follicles in the posterior pharyngeal wall, sometimes with cobblestone-like changes, or with mucus-like or purulent secretions attached.
(3) Antihistamines, leukotriene receptor antagonists and nasal glucocorticoids are effective for chronic cough caused by allergic rhinitis, and chronic cough caused by purulent sinusitis requires antibacterial medication for 2-4 weeks.
(4) Nasopharyngoscopy or lateral head and neck films, sinus x-rays or CT films may be helpful for diagnosis.
III. Etiology of atopic cough requiring differential diagnosis
1. Congenital respiratory diseases.
It is mainly seen in infants and young children, especially within 1 year of age. These include congenital esophageal-tracheal fistula, congenital vascular malformation compressing the airway, laryngeal-tracheal-bronchial softening and/or stenosis, bronchial-pulmonary cyst, primary ciliary dyskinesia, and embryonic-derived mediastinal tumors. Once it is clear that these disorders cause chronic cough, it is classified as atopic cough.
2. Foreign body aspiration.
Cough is the most common symptom of foreign body aspiration in the airway, and a clear diagnosis should be classified as an atopic cough. Foreign body inhalation is an important cause of chronic cough in children, especially those aged 1-5 years. Studies have found that 70% of patients with foreign body aspiration present with a cough and other symptoms such as decreased breath sounds and wheezing, and there may be a history of asphyxia. The cough usually appears as a paroxysmal violent choking cough, or it may only appear as a chronic cough with obstructive emphysema or atelectasis, and once the foreign body enters below the small bronchus, there can be no cough, which is also known as entering the “silent zone”.
3. Respiratory tract infections caused by specific pathogens.
Respiratory infections caused by a variety of pathogenic microorganisms such as Mycobacterium pertussis, Mycobacterium tuberculosis, viruses, Mycoplasma pneumoniae and Chlamydia can also cause chronic cough in children, and once a clear diagnosis is made, it is classified as an atopic cough. In our country, pertussis is a severely underestimated d,JL acute respiratory infection, especially in infants under 3 months of age who have not yet received the DPT vaccine and in those for whom the level of antibodies produced by the DPT vaccine is no longer sufficient for effective protection (school-age children).
4. Prolonged bacterial bronchitis (protract/, PBB).
PBB is one of the causes of atopic chronic cough in infantile and preschool-aged children and requires the attention of pediatric clinicians. It has been referred to as purulent bronchitis, migratory bronchitis, and pre-bronchodilatation, among others, and refers to a persistent infection of the bronchial lining caused by bacteria. The causative agents of PBB are mainly Haemophilus influenzae (especially Haemophilus influenzae untyped) and Streptococcus pneumoniae, etc., and rarely caused by gram-negative bacilli.
Clinical features and diagnostic clues.
(1) wet (sputum-bearing) cough lasting >4 weeks.
(2) Bronchial wall thickening and suspected bronchiectasis, but rarely pulmonary hyperinflation, as seen on high-resolution CT films of the chest, which are distinct from asthma and fine bronchiectasis.
(3) Cough improves significantly with antimicrobial therapy for more than 2 weeks.
(4) elevated neutrophils and/or positive bacterial culture on bronchoalveolar lavage fluid examination; (5) chronic cough from other causes excluded.