17-74% of patients with chronic obstructive pulmonary disease have chronic bronchitis, the typical symptom of which is chronic cough, sputum production. What bothers many COPD patients is "difficulty in excreting sputum", and sputum is not discharged in time, which will block the airway, causing hypoxia and breathing difficulties in the body, which will aggravate the condition.
Why do PEOPLE WITH COPD "cough up sputum"?
Dr. Lu Jinghui of the Beijing Anzhen Community Health Service Center elaborated on the causes of SPutum production in PATIENTS: superficial epidermal metaplasia and submucosal gland dilation, as well as cilia dysfunction.
Figure 1 Ciliary motion from the network
Our normal human airway presence ciliate cleaning system depends on a layer of mucus with proper flow, a layer around cilia of appropriate depth, and an effective ciliate jump swing. When these components interact optimally, particles and pathogens suspended in the 10,000 liters of air inhaled per day are cleared from the lungs with minimal effect on epithelial cells (Figure 2). However, the failure of any of these components can lead to dysfunction, which leads to symptoms and leads to the onset of disease.
Figure 2: The presence of a mucus circulation system in the airway ensures a clean airway and a normal immune barrier. A normal airway produces mucus, the swaying cilia move the mucus from the distal end of the airway to the mouth, and the mucus with dust and germs is swallowed by the mouth into the esophagus. B Light blue is the flowing mucus layer, and dark blue is the layer around the dense cilia.
Due to the pathophysiological basis of COPD, the airway epithelial cells produce mucus, which in turn produces a series of respiratory reactions (Figure 3). When mucus secretes too much, it can cause cilia dysfunction of the airway, causing ineffective oscillation, thereby blocking the airway, resulting in poor sputum drainage, affecting effective ventilation. Excess mucus can also become a medium for pathogenic bacteria, causing the occurrence and aggravation of infection, thus affecting the outcome of the disease. These excess mucus, along with components such as pathogenic microorganisms, inflammatory cells, and necrotic hepatocytes (such as mucosal epithelial cells), make up sputum.
Figure 3: Inflammatory cells on the right, oxidative stress, viral and bacterial infections stimulate increased mucus secretion. Excessive secretion of the mucus airways results in decreased self-cleaning, airway blockage, decreased peak flow rate, and weakened respiratory muscle function.
How do PEOPLE WITH COPD choose "expectorant drugs"?
Therefore, effective expectorants are important auxiliary measures for the treatment of such diseases, and the mechanism of action of expectorants can be roughly divided into:
1. Improve the physicochemical properties of sputum and reduce sputum viscosity;
2. Restore the normal structure of the mucus layer of the epithelium of the airway and promote the removal function of cilia;
3. Inhibit the production and secretion of mucin, destroy the mucus structure in sputum;
4. Anti-inflammatory damage, or enhance antibacterial effect.
Dr. Lu Jinghui introduced in detail the common sputum drugs commonly used in the clinical treatment of chronic bronchitis and COPD:
1. Mucus dissolving agent
Mainly including: acid glycoprotein dissolvers, disulfide bond cleavants, proteolytic enzymes (not commonly used).
1. Acid glycoprotein dissolving agent: can break the acidic protein fiber in sputum, thereby reducing the viscosity of sputum. Common drugs: ambroxol and bromine have been renewed and can be used for COPD.
2. Disulfide bond cleaver: containing thiol amino acids, through the exchange of thiol groups and mucin disulfide bonds to cleave the mucin molecules, while also has a certain lysis effect on DNA fibers, thereby reducing sputum viscosity. Common drugs: acetylcysteine, carboxylsteine and erdostam, can be used for COPD, in which erdostam improves COPD prognosis.
2. Disgusting expectorant
After oral administration, it will stimulate the afferent fibers of the gastric mucosal vagus nerve, causing mild nausea, reflex excitation innervates the vagus nerve efferent branch of the trachea-bronchial mucosal gland, promotes glandular secretion, dilutes sputum, and improves the clearance function of mucus.
Common drugs: guaiacyl ether, compound fresh bamboo drain.
3. Vegetable oil
Mechanism of action:1. 2. Regulate airway secretion, increase the proportion of serous fluid, and improve mucus removal function; 2. Adjust the pH of the mucus to reduce the viscosity; 4. Promote ciliary movement and speed up mucus transport; Has a certain anti-inflammatory and bactericidal use.
Representative drugs: Myrtle oil, eucalyptus capsules are also such drugs, which are commonly used drugs for COPD.
In addition to the above-mentioned expectorant drugs in the traditional sense, β2-receptor agonists, anticholinergic drugs and glucocorticoids can also exert expectorant effects.
Dr. Lu Jinghui said that the fourth type of bronchodilators and glucocorticoids are the basic treatment drugs for COPD, on this basis, the first three types of drugs can be selected, the first three types are drugs that change the nature of sputum, COPD patients can choose 1 or several types of combined application, but the same kind of drugs are generally not combined.
Expert Profile Lu Jinghui
Attending Physician; Anzhen Community Health Service Center. Graduated from Peking University School of Medicine, Ph.D. After graduation, he engaged in respiratory critical care, stayed in the United States in 2018, studied at Harvard Medical School, engaged in postdoctoral research, published a number of academic papers, and devoted himself to clinical and research work in general medicine after returning to China at the end of 2019.
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