Acute tracheobronchitis is an acute inflammation of the tracheobronchial mucosa caused by infection, physical or chemical irritation or allergic reaction. It is often caused by viral and bacterial invasion of the lower respiratory tract, but can also arise from acute upper respiratory tract infections. It occurs in the cold season or during sudden changes in climate and is mainly characterized by cough and sputum. The common causes are ① viral or bacterial infections: common pathogenic bacteria such as Haemophilus influenzae, pneumococcus, streptococcus, staphylococcus and Nocardia; ② physical and chemical factors: acute irritation of tracheobronchial mucosa by cold air, dust, irritant gases or fumes (such as carbon dioxide, nitrogen dioxide, ammonia, chlorine, etc.); ③ allergic reactions: inhalation of pollen, organic dust, fungal spores, etc. (3) Allergic reactions: inhalation of pollen, organic dust, fungal spores, larvae of hookworms or roundworms in the lungs, allergy to bacterial proteins, etc. cause allergic inflammatory reactions in the trachea and bronchi. Clinical manifestations Usually the onset of the disease is acute, manifested as cough and sputum, first dry cough or a small amount of mucus sputum, later may turn into mucopurulent, sputum volume increases, cough intensifies, and occasionally sputum with blood. If bronchial spasm occurs, shortness of breath, paroxysmal cough or tightness in the chest may occur in varying degrees. The cough and sputum may last for 2 to 3 weeks before disappearing, and may evolve into chronic bronchitis if it does not resolve. Systemic symptoms are usually mild and may include fever of about 38°C, which mostly decreases to normal in 3 to 5 days. Physical examination of the lungs can be normal breath sounds in both lungs on auscultation, but also scattered dry and wet rales, the site of the rales are often not fixed, and can be reduced or disappear after coughing. Routine blood tests: white blood cell count and classification do not change significantly. In bacterial infections, the total white blood cell count and neutrophil count may be increased. The sputum smear or culture can detect pathogenic bacteria. Treatment The principles of treatment are infection control, expectoration, cough suppression, wheezing, antipyretic and analgesic and supportive treatment. (1) General treatment: light diet, drinking more water, proper rest, avoiding triggering factors and inhalation of allergens. Keep indoor air circulation and fresh air, prevent cold and flu, exercise, and enhance the body’s resistance to disease. (2) Antibacterial drugs: select antibacterial drugs according to pathogens and drug sensitivity tests. Generally start treatment with lack of pathogenic bacteria results, macrolides, penicillins, cephalosporins, fluoroquinolones, etc. can be used. The route of medication depends on the condition, the milder cases can be taken orally, the severe cases can be given intramuscularly or intravenously. (3) Symptomatic treatment: antipyretic and analgesic drugs such as compound aspirin can be applied in case of fever and headache; expectorants such as ammonium chloride combination, bromhexine and aminobromine hydrochloride can be used in case of cough with sputum and not easy to cough up; dextromethorphan, pentoxifylline (coughing) and codeine can be used in case of severe cough without sputum; wheezing drugs such as theophylline and β2-adrenergic agonists can be used in case of bronchospasm.