Definition A cough with symptoms lasting >4 weeks is called a chronic cough.
Etiology
I. Age characteristics
Age should be fully considered in the clinical diagnosis of chronic cough in children, and the common etiology of chronic cough in children of different ages varies.
II. Specific cough
This refers to a cough accompanied by other symptoms or signs that are indicative of a specific 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 on auscultation or croup often indicates intrathoracic airway pathology such as tracheobronchitis, asthma, congenital airway developmental abnormalities (e.g. tracheobronchial softening), etc.; cough accompanied by shortness of breath, hypoxia or cyanosis indicates pulmonary inflammation; cough accompanied by growth disorders, pestle fingers (toes) often indicates severe chronic lung disease and congenital heart disease, etc.; cough accompanied by Those with pus sputum suggest pulmonary inflammation, bronchiectasis, etc.; those with hemoptysis suggest severe pulmonary infection, pulmonary vascular disease, pulmonary ferritinosis or bronchiectasis, etc.
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 “narrow chronic cough”. The causes of nonspecific cough in children are age-specific and require careful systematic evaluation, thorough history taking, and physical examination.
1. Respiratory tract infection. With postinfectious cough (respiratory infections and postinfectious cough): respiratory infections caused by many pathogenic microorganisms such as Mycobacterium pertussis, Mycobacterium tuberculosis, viruses (especially respiratory syncytial virus, parainfluenza virus, cytomegalic inclusion body virus), Mycoplasma pneumoniae, and Chlamydia are common causes of chronic cough in children It is a common cause of chronic cough in children, mostly in preschool children <5 years of age.
2. Acute respiratory infections with cough symptoms lasting more than 4 weeks can be considered as post-infectious cough. The mechanism may be disruption of airway epithelial integrity and/or squamification of ciliated 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 infection.
(2) Cough that is irritatingly dry or accompanied by a small amount of white mucous sputum.
(3) No abnormalities on chest radiographs.
(4) Normal pulmonary ventilation function.
(5) 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.
Cough variant asthma (CVA): CVA is a common cause 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 nocturnal and/or early morning onset, aggravated by exercise, exposure to cold air, and no clinical signs of infection or ineffective after prolonged antibiotic treatment.
(2) Diagnostic treatment with bronchodilators results in significant relief of cough symptoms.
(3) Normal pulmonary ventilation with bronchial excitation tests suggesting airway hyperresponsiveness.
(4) 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 (UACS): 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 drainage (flow) syndrome (PNDs). The ACPP recommends the name upper airwaycough syndrome (UACS) to replace PNDs.
The clinical features and diagnostic clues of UACS are.
(1) chronic cough with or without coughing sputum, which 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 mucus-like attachment to the posterior pharyngeal wall can be seen.
(3) Targeted treatment such as antihistamines and leukotriene receptor antagonists, and nasal glucocorticoids are effective.
(4) sinusitis, sinus x-ray or CT film can be seen in the corresponding changes.
4. gastroesophageal reflux cough (GERC): GER is a physiological phenomenon in infancy and early childhood. The incidence of GER in healthy infants is 40% to 65%, peaking at 1 to 4 months of age, and mostly resolving spontaneously 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].
5. 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. (2) Some children have epigastric or subxiphoid discomfort, retrosternal burning sensation, chest pain, and sore throat.
(3) In addition to causing coughing, the infant may also suffer from asphyxia, bradycardia, and an arched back.
(4) It can lead to stagnant or delayed growth of the affected child.
6. eosinophilic bronchitis (EB): 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].
The 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 treatment with oral or inhaled glucocorticoids.
7, congenital respiratory disorders: mainly seen in infants and children, especially within 1 year of age. Gormley’s study reported that 75% of children with tracheoesophageal cartilage (second only to congenital vascular malformation) have persistent cough, and the mechanism may be related to tracheal cartilage obstructing the discharge of secretions and inflammatory damage to the terminal bronchi. The mechanism may be related to the obstruction of secretion drainage and inflammatory damage to the terminal bronchi. This condition is often misdiagnosed as asthma.
8. 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 characteristics are only suggestive of psychogenic cough, not diagnostic [E/B].
The clinical features and diagnostic clues of psychogenic cough are.
(1) prevalence in older children.
(2) A predominantly daytime cough that disappears when focused on an event or at rest at night.
(3) It is often accompanied by symptoms of anxiety.
(4) No organic disease and other causes of chronic cough are excluded.
9. Other etiologies.
(1) Foreign body aspiration (foreign bodya spiration): cough is the most common symptom after aspiration of foreign bodies from the airway, and foreign body aspiration is an important cause of chronic cough in children, especially those aged 1-3 years. Studies have found that 70% of patients with foreign body aspiration present with cough, and other symptoms include decreased breath sounds, wheezing, and a history of asphyxia. Once the foreign body enters the area below the small bronchus, there can be no cough, which is called the “silent zone”.
(2) Drug-inducedcough: 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 ACEI 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 after 3-7 d of drug withdrawal.
(3) Otogenic cough: 2%-4% of the population has the vagus nerve branch (arnold nerve). In this group, when the middle ear is diseased, the vagus nerve becomes irritated and causes a chronic cough. Otogenic cough is a rare cause of chronic cough in children.
Diagnosis of chronic cough in children and its process
Diagnostic tools
1. History and physical examination: Take a detailed history to find out the cause of chronic cough, including physical, chemical and biological causes, which is important for the diagnosis of the cause. Pay attention to the nature of the cough, such as barking, goose, intermittent or paroxysmal, and the aggravating factors of the cough and its accompanying symptoms. In chronic cough with sputum, attention should be paid to the presence of bronchiectasis and underlying diseases such as cystic fibrosis and immunodeficiency disease. Physical examination of the lungs and heart, the presence of nail bed cyanosis,
pestle finger, etc. Pay attention to the assessment of the child’s growth and development, respiratory rate, and the presence of thoracic deformities.
2.Auxiliary examinations.
(1) Radiological examination: routine chest X-ray should be performed in children with chronic cough, and the next diagnostic treatment or examination should be decided based on whether the chest X-ray is normal or not. A cavitation is taken when sinusitis is suspected or further consultation at the Department of Otolaryngology is recommended. CT of the chest helps to detect small and medium-sized lesions in the mediastinum, hilar lymph nodes and lung fields, while high-resolution CT helps to diagnose atypical bronchiectasis, pulmonary interrogative disease, etc. CT sinus films showing thickening of the nasal mucosa >4mm or air-fluid flat or fuzzy opacities in the sinus cavity are characteristic changes of raised sinusitis. CT and MRI of the sinus region is one of the indispensable diagnostic tools, but it should not be included as a routine test and can be performed at the discretion of the doctor depending on the condition. The interpretation of the results also needs to be cautious in children, especially in children under 1 year of age, because the sinuses are not well developed (maxillary sinus and septal sinus exist at birth but are small, while frontal sinus and pterygoid sinus appear only at the age of 5-6 years) and the structure is not clear, so imaging alone can easily lead to overdiagnosis of “sinusitis”.
(2) Pulmonary function: Pulmonary ventilation function tests should be routinely performed in children over 5 years of age. If necessary, further bronchodilatation tests or bronchial excitation tests can be performed according to the force expiratory volume in one second (FEVl) to assist in the diagnosis of asthma (including CVA) and the differentiation from EB.
(3) Bronchoscopy (fiberoptic bronchoscopy, rigid bronchoscopy, etc.): bronchoscopy is feasible for chronic cough caused by suspected airway developmental malformations, foreign bodies (including airway endogenous foreign bodies and sputum plugs), and when anti-pollution pathogenic microbial examination is required.
(4) Induced sputum or bronchoalveolar lavage fluid cytology and isolated culture of pathogenic microorganisms: can clarify or suggest the pathogen of respiratory tract infection, and if eosinophils are elevated, it is the main indicator for the diagnosis of allergic inflammatory diseases such as EB.
(5) Others: PPD skin test, serum total IgE and specific IgE determination, skin prick test (SPT), 24-hour esophageal pH monitoring, esophageal intraluminal impedance test, etc. While the diagnostic value of exhaled breath nitric oxide assay, tracheobronchial biopsy, and cough receptor sensitivity testing for chronic cough in children
The value of these tests is uncertain.
Diagnostic procedures
Pediatricians should be aware that chronic cough is only a symptom and that the clinical cause of chronic cough should be clarified as much as possible. The diagnostic procedure should range from simple to complex, from common to rare diseases. Diagnostic treatment contributes to the diagnosis of chronic cough in children and is based on the principle that in the absence of a clear indication of the cause, diagnostic treatment should be performed in the order of UACS, CVA, and GERC [E/B].
Treatment
The principle of management of chronic cough in children is to identify the cause and treat it for that cause [E/A]. If the etiology is unknown, empirical symptomatic treatment may be administered with a view to achieving effective control; if cough symptoms do not resolve after treatment, they should be reassessed. ACCP recommends that the expectations of parents should be taken into account in the management of non-specific chronic cough in children [E/B] and emphasizes the importance of post-treatment follow-up and re-evaluation, i.e. watch, wait and review.
I. Drug therapy
1. Expectorant drugs: If chronic cough is accompanied by sputum, the principle of expectorant should be adopted, and the cough should not be stopped simply to avoid aggravating or causing airway obstruction.
2, antihistamines: H1 receptor antagonists such as chlorpheniramine, loratadine, cetirizine, etc. can be used to treat UACS.
3, antibacterial drugs: antibacterial drugs can be considered for chronic cough with clear bacterial or Mycoplasma pneumoniae or Chlamydia pathogenic infections. Macrolide antibiotics, including erythromycin, azithromycin, and clarithromycin, may be chosen for Mycoplasma pneumoniae or Chlamydia infections. After initial experience with other pathogenic infections, if antibiotics need to be adjusted, they should be selected according to the results of drug sensitivity tests.
4. Asthma and anti-inflammatory drugs: including glucocorticoids, β2 agonists, M-blockers, leukotriene receptor antagonists, theophylline and other drugs. Mainly used for the targeted treatment of CVA, EB, allergic rhinitis, etc. Glucocorticoid therapy should be re-evaluated after 2 to 4 weeks [ B]. Post-infection cough can generally resolve on its own, and short-term use of inhaled or oral glucocorticoids, leukotriene receptor antagonists or M receptor blockers can be considered for those with severe symptoms.
5. Digestive system drugs: H2 receptor antagonists such as cimetidine and pro-gastric motility drugs such as domperidone are advocated [E/B]. Lack of experience with proton pump inhibitors in children.
6. Cough suppressants: The use of cough suppressants is not advocated for chronic cough especially before the cause is clear, and the use of such drugs is associated with morbidity and mortality from a number of diseases, and the American Academy of Pediatrics warns that codeine is contraindicated for the treatment of all types of cough [A]. The sedative effect of promethazine (finasteride) has the potential to mislead parents to apply the drug to reduce their child’s fussiness while ignoring the adverse effects of the drug, including irritability, hallucinations, abnormal muscle tone, and even apnea and sudden infant death. Adverse effects were evident in infants, leading the WHO to warn that promethazine is contraindicated in children under 2 years of age and is prohibited as a cough suppressant [A]. The Cochrane review of symptomatic treatment of pertussis also noted no significant benefit from the use of diphenhydramine [E/A].
II. Non-pharmacological treatment
Pay attention to the removal or avoidance of factors that trigger or aggravate cough.
1. Avoid exposure to allergens, exposure to cold, and smoky environments [ B].
2. nasal irrigation and selection of decongestants for sinusitis.
3. changes in body position, changes in food properties, and small and frequent meals are effective for GERC
4, for foreign bodies in the airway should be promptly removed foreign bodies.
5. the best treatment for drug-induced, cough is to stop the drug.
6. psychotherapy can be given for psychogenic cough.
7. Timely vaccination to prevent respiratory infections and respiratory tract infections.