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Emergency and Acute Medicine – Cough
Physiologic Basis and Clinical Overview
Cough is a sudden, forceful, spasmodic contraction of the thoracic cavity that results in the rapid expulsion of air from the lungs, typically producing a characteristic sound. The cough mechanism begins with a deep inspiration followed by closure of the glottis, contraction of expiratory muscles, and a marked rise in intrapulmonary pressure. When the glottis opens, air is expelled at high velocity, facilitating the clearance of secretions and foreign material. Vibration of the vocal cords in conjunction with the tracheobronchial walls, lung parenchyma, and airway secretions produces the audible cough.
Cough serves as a vital protective defense mechanism for clearing the airway and may occur voluntarily or involuntarily. Involuntary coughing is mediated through vagal afferent nerves, while voluntary coughing is under cortical control, allowing suppression or intentional initiation. Because of this cortical influence, placebo effects can significantly impact cough frequency and severity. The reflex arc involves activation of respiratory tissue receptors, transmission through afferent neurons to the central cough center, and efferent signaling to the respiratory muscles. Mechanical receptors located in the larynx, trachea, and carina respond to touch and displacement, whereas chemical receptors in the larynx and bronchi respond to gases, fumes, mucus, edema, pus, and thermal stimuli.
Severe or persistent coughing may result in complications including epistaxis, subconjunctival hemorrhage, syncope, pneumothorax, pneumomediastinum, emesis, hernia formation, rectal prolapse, urinary or fecal incontinence, seizures, encephalitis, intracranial hemorrhage, spinal epidural hemorrhage, digital clubbing, and pruriginous rash.
Etiology and Duration-Based Classification
Acute cough, defined as lasting less than three weeks, is most commonly caused by pneumonia, acute bronchitis, sinusitis, pertussis, tuberculosis, upper respiratory tract infections, cough-variant asthma, COPD exacerbations, bronchiectasis, pulmonary embolism, left ventricular failure, airway obstruction from food or pills, gastroesophageal reflux disease, allergies, and bronchospasm.
Subacute cough, lasting three to eight weeks, is often postinfectious in origin and may be associated with pertussis, bronchitis, bacterial sinusitis, asthma, GERD, or pulmonary embolism.
Chronic cough, persisting for more than eight weeks, is commonly due to postnasal drip, asthma, GERD, chronic bronchitis, tuberculosis, bronchiectasis, eosinophilic bronchitis, ACE inhibitor use, bronchogenic carcinoma, carcinomatosis, sarcoidosis, left ventricular failure, aspiration syndromes, or psychogenic and habitual causes.
Pediatric Considerations
In children, the most frequent causes of cough include asthma, viral respiratory illness, acute bronchitis, pneumonia, sinusitis, and GERD. Less common causes include tracheobronchomalacia, mediastinal tumors, acyanotic congenital heart disease such as ventricular septal defect or patent ductus arteriosus, pulmonary stenosis, tetralogy of Fallot, retained airway foreign bodies, chronic milk aspiration, and environmental exposures. Evaluation should incorporate neonatal history, feeding patterns, growth and developmental milestones, allergy history, eczema, and sleep disorders. Chest radiography is indicated when foreign body ingestion or aspiration is suspected.
Clinical Features
Cough may be productive or nonproductive. Frothy sputum suggests pulmonary edema, while mucopurulent sputum is often associated with bacterial pneumonia or bronchitis but may also occur in viral infections. Rust-colored sputum suggests pneumococcal pneumonia, and “currant jelly” sputum is characteristic of Klebsiella pneumoniae. Hemoptysis may occur in a variety of conditions. Post-tussive syncope or emesis and paroxysmal coughing are suggestive of pertussis. Associated symptoms include shortness of breath, chest pain, fever, chills, night sweats, and wheezing. GERD-related cough may be accompanied by heartburn, dysphagia, regurgitation, belching, or early satiety. Weight loss, poor appetite, and fatigue raise concern for malignancy.
History should focus on cough duration to classify it as acute, subacute, or chronic, sputum characteristics including hemoptysis, and the presence of post-tussive emesis or syncope. Gastrointestinal symptoms may suggest GERD, while weight loss and night sweats in chronic cough raise suspicion for tuberculosis.
Physical Examination
Vital signs should be carefully assessed. Lung examination may reveal absent or decreased breath sounds suggesting reduced airflow or hyperinflation, crackles indicating alveolar opening, rhonchi from large airway obstruction, wheezes from narrowed airways, or stridor indicating upper airway obstruction. Signs of respiratory distress include use of accessory muscles and abdominal breathing.
Essential Diagnostic Approach
A comprehensive medical history should include cough duration, associated symptoms, exposure to sick contacts, smoking history, ACE inhibitor use, immunocompromised status including HIV, and potential tuberculosis exposure. Electrocardiography is indicated in patients with cardiac disease, chest pain, abnormal vital signs, or absence of infectious symptoms.
Laboratory studies should be guided by clinical presentation and may include a complete blood count with differential, sputum Gram stain and culture, acid-fast bacilli testing, CD4 count, pertussis serology, D-dimer testing, and influenza testing in high-risk or hospitalized patients.
Chest radiography is indicated for immunocompromised patients and in otherwise healthy patients with acute cough and sputum production when accompanied by tachycardia, tachypnea, fever above 38°C, focal lung findings, ill appearance, change in chronic cough pattern, or persistence of cough after discontinuation of an ACE inhibitor. Chest CT is reserved for abnormal radiographs or evaluation for pulmonary embolism. Peak flow testing may assist in asthma evaluation, while bronchoscopy is indicated for unexplained masses on imaging, hemoptysis, or suspected malignancy.
Differential Diagnosis
The differential diagnosis mirrors the etiologic categories described above and should be guided by duration, associated symptoms, and patient risk factors.
Emergency Department Management
Initial evaluation requires assessment of airway, breathing, and circulation. Treatment is directed at the underlying cause. Respiratory infections may require antibiotics, antivirals for influenza, decongestants, or antitussives. Asthma exacerbations are treated with inhaled beta-agonists and corticosteroids. GERD-related cough is managed with H2 blockers, proton pump inhibitors, and antacids. Suspected pertussis requires macrolide therapy and five days of isolation. Exacerbations of chronic bronchitis are treated with inhaled beta-agonists and steroids. Malignancy-related cough is managed with supportive care.
Pharmacologic Therapy
Antibiotic selection should target the suspected pathogen. Antiviral therapy includes oseltamivir at standard adult and pediatric dosing. Antitussives such as codeine, dextromethorphan, and hydrocodone may be used judiciously. Bronchodilators include inhaled albuterol and ipratropium. Decongestants such as chlorpheniramine and phenylpropanolamine may be used when indicated. Mucolytics such as guaifenesin aid secretion clearance. Corticosteroids may include intranasal dexamethasone or systemic methylprednisolone or prednisone, depending on severity and etiology.
Disposition and Follow-Up
Hospital admission is warranted for patients with hypoxemia, critical illness, suspected tuberculosis with radiographic findings, immunocompromised patients with fever, or those at risk for sepsis or bacteremia. Patients may be discharged if oxygenation is at baseline, oral medications are tolerated, and a safe home environment is assured. Close outpatient follow-up with a primary care physician is recommended.
Patient Guidance and Preventive Measures
Patients should be advised to stop smoking and avoid exposure to tobacco smoke, asbestos, and other respiratory irritants. Dietary modifications for GERD include avoiding caffeine-containing beverages, refraining from eating at least four hours before bedtime, and elevating the head during sleep. Immediate medical attention is required for chest pain, hemoptysis, shortness of breath, or syncope.
Key Clinical Insights and Common Errors
For patients whose clinical presentation is consistent with GERD-related cough, empiric treatment is recommended before pursuing diagnostic testing. In cases of presumed acute bronchitis, routine antibiotic therapy is not supported by evidence and should be avoided.
Physiologic Basis and Clinical Overview
Cough is a sudden, forceful, spasmodic contraction of the thoracic cavity that results in the rapid expulsion of air from the lungs, typically producing a characteristic sound. The cough mechanism begins with a deep inspiration followed by closure of the glottis, contraction of expiratory muscles, and a marked rise in intrapulmonary pressure. When the glottis opens, air is expelled at high velocity, facilitating the clearance of secretions and foreign material. Vibration of the vocal cords in conjunction with the tracheobronchial walls, lung parenchyma, and airway secretions produces the audible cough.
Cough serves as a vital protective defense mechanism for clearing the airway and may occur voluntarily or involuntarily. Involuntary coughing is mediated through vagal afferent nerves, while voluntary coughing is under cortical control, allowing suppression or intentional initiation. Because of this cortical influence, placebo effects can significantly impact cough frequency and severity. The reflex arc involves activation of respiratory tissue receptors, transmission through afferent neurons to the central cough center, and efferent signaling to the respiratory muscles. Mechanical receptors located in the larynx, trachea, and carina respond to touch and displacement, whereas chemical receptors in the larynx and bronchi respond to gases, fumes, mucus, edema, pus, and thermal stimuli.
Severe or persistent coughing may result in complications including epistaxis, subconjunctival hemorrhage, syncope, pneumothorax, pneumomediastinum, emesis, hernia formation, rectal prolapse, urinary or fecal incontinence, seizures, encephalitis, intracranial hemorrhage, spinal epidural hemorrhage, digital clubbing, and pruriginous rash.
Etiology and Duration-Based Classification
Acute cough, defined as lasting less than three weeks, is most commonly caused by pneumonia, acute bronchitis, sinusitis, pertussis, tuberculosis, upper respiratory tract infections, cough-variant asthma, COPD exacerbations, bronchiectasis, pulmonary embolism, left ventricular failure, airway obstruction from food or pills, gastroesophageal reflux disease, allergies, and bronchospasm.
Subacute cough, lasting three to eight weeks, is often postinfectious in origin and may be associated with pertussis, bronchitis, bacterial sinusitis, asthma, GERD, or pulmonary embolism.
Chronic cough, persisting for more than eight weeks, is commonly due to postnasal drip, asthma, GERD, chronic bronchitis, tuberculosis, bronchiectasis, eosinophilic bronchitis, ACE inhibitor use, bronchogenic carcinoma, carcinomatosis, sarcoidosis, left ventricular failure, aspiration syndromes, or psychogenic and habitual causes.
Pediatric Considerations
In children, the most frequent causes of cough include asthma, viral respiratory illness, acute bronchitis, pneumonia, sinusitis, and GERD. Less common causes include tracheobronchomalacia, mediastinal tumors, acyanotic congenital heart disease such as ventricular septal defect or patent ductus arteriosus, pulmonary stenosis, tetralogy of Fallot, retained airway foreign bodies, chronic milk aspiration, and environmental exposures. Evaluation should incorporate neonatal history, feeding patterns, growth and developmental milestones, allergy history, eczema, and sleep disorders. Chest radiography is indicated when foreign body ingestion or aspiration is suspected.
Clinical Features
Cough may be productive or nonproductive. Frothy sputum suggests pulmonary edema, while mucopurulent sputum is often associated with bacterial pneumonia or bronchitis but may also occur in viral infections. Rust-colored sputum suggests pneumococcal pneumonia, and “currant jelly” sputum is characteristic of Klebsiella pneumoniae. Hemoptysis may occur in a variety of conditions. Post-tussive syncope or emesis and paroxysmal coughing are suggestive of pertussis. Associated symptoms include shortness of breath, chest pain, fever, chills, night sweats, and wheezing. GERD-related cough may be accompanied by heartburn, dysphagia, regurgitation, belching, or early satiety. Weight loss, poor appetite, and fatigue raise concern for malignancy.
History should focus on cough duration to classify it as acute, subacute, or chronic, sputum characteristics including hemoptysis, and the presence of post-tussive emesis or syncope. Gastrointestinal symptoms may suggest GERD, while weight loss and night sweats in chronic cough raise suspicion for tuberculosis.
Physical Examination
Vital signs should be carefully assessed. Lung examination may reveal absent or decreased breath sounds suggesting reduced airflow or hyperinflation, crackles indicating alveolar opening, rhonchi from large airway obstruction, wheezes from narrowed airways, or stridor indicating upper airway obstruction. Signs of respiratory distress include use of accessory muscles and abdominal breathing.
Essential Diagnostic Approach
A comprehensive medical history should include cough duration, associated symptoms, exposure to sick contacts, smoking history, ACE inhibitor use, immunocompromised status including HIV, and potential tuberculosis exposure. Electrocardiography is indicated in patients with cardiac disease, chest pain, abnormal vital signs, or absence of infectious symptoms.
Laboratory studies should be guided by clinical presentation and may include a complete blood count with differential, sputum Gram stain and culture, acid-fast bacilli testing, CD4 count, pertussis serology, D-dimer testing, and influenza testing in high-risk or hospitalized patients.
Chest radiography is indicated for immunocompromised patients and in otherwise healthy patients with acute cough and sputum production when accompanied by tachycardia, tachypnea, fever above 38°C, focal lung findings, ill appearance, change in chronic cough pattern, or persistence of cough after discontinuation of an ACE inhibitor. Chest CT is reserved for abnormal radiographs or evaluation for pulmonary embolism. Peak flow testing may assist in asthma evaluation, while bronchoscopy is indicated for unexplained masses on imaging, hemoptysis, or suspected malignancy.
Differential Diagnosis
The differential diagnosis mirrors the etiologic categories described above and should be guided by duration, associated symptoms, and patient risk factors.
Emergency Department Management
Initial evaluation requires assessment of airway, breathing, and circulation. Treatment is directed at the underlying cause. Respiratory infections may require antibiotics, antivirals for influenza, decongestants, or antitussives. Asthma exacerbations are treated with inhaled beta-agonists and corticosteroids. GERD-related cough is managed with H2 blockers, proton pump inhibitors, and antacids. Suspected pertussis requires macrolide therapy and five days of isolation. Exacerbations of chronic bronchitis are treated with inhaled beta-agonists and steroids. Malignancy-related cough is managed with supportive care.
Pharmacologic Therapy
Antibiotic selection should target the suspected pathogen. Antiviral therapy includes oseltamivir at standard adult and pediatric dosing. Antitussives such as codeine, dextromethorphan, and hydrocodone may be used judiciously. Bronchodilators include inhaled albuterol and ipratropium. Decongestants such as chlorpheniramine and phenylpropanolamine may be used when indicated. Mucolytics such as guaifenesin aid secretion clearance. Corticosteroids may include intranasal dexamethasone or systemic methylprednisolone or prednisone, depending on severity and etiology.
Disposition and Follow-Up
Hospital admission is warranted for patients with hypoxemia, critical illness, suspected tuberculosis with radiographic findings, immunocompromised patients with fever, or those at risk for sepsis or bacteremia. Patients may be discharged if oxygenation is at baseline, oral medications are tolerated, and a safe home environment is assured. Close outpatient follow-up with a primary care physician is recommended.
Patient Guidance and Preventive Measures
Patients should be advised to stop smoking and avoid exposure to tobacco smoke, asbestos, and other respiratory irritants. Dietary modifications for GERD include avoiding caffeine-containing beverages, refraining from eating at least four hours before bedtime, and elevating the head during sleep. Immediate medical attention is required for chest pain, hemoptysis, shortness of breath, or syncope.
Key Clinical Insights and Common Errors
For patients whose clinical presentation is consistent with GERD-related cough, empiric treatment is recommended before pursuing diagnostic testing. In cases of presumed acute bronchitis, routine antibiotic therapy is not supported by evidence and should be avoided.
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