Acute Bronchitis: Understanding, Diagnosis, and Management
Introduction
Acute bronchitis is a common clinical condition characterized by inflammation of the trachea and large airways, resulting in a persistent cough. It primarily affects adults and has significant implications for healthcare systems, especially due to the frequent but often inappropriate prescription of antibiotics.
Etiology and Pathogenesis
The majority of acute bronchitis cases are viral in origin. The most commonly implicated viruses include:
• Influenza A and B
• Parainfluenza
• Respiratory syncytial virus (RSV)
• Coronavirus
• Adenovirus
• Rhinovirus
In some instances, bacteria such as Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Bordetella pertussis may be responsible, particularly in prolonged cases of cough.
Clinical Presentation and Special Symptoms
Acute bronchitis is primarily characterized by a persistent cough, typically lasting about two to three weeks. The following symptoms are commonly observed:
1. Cough:
• Primary Symptom: Persistent cough, which may be dry or productive of sputum. Severe enough to cause chest wall pain.
• Duration: Typically lasts for two to three weeks, with a pooled estimate of 18 days in one systematic review.
2. Sputum Production:
• Characteristics: Sputum may be clear, white, yellow, or green. Color does not correlate well with bacterial infection.
3. Wheezing:
• Occurrence: Particularly in patients with preexisting reactive airway disease. Results from bronchial hyperreactivity and inflammation.
4. Dyspnea:
• Description: Mild shortness of breath, especially during exertion. Should be evaluated to rule out serious conditions such as pneumonia or heart failure.
5. Fever:
• Prevalence: Low-grade fever may be present initially but is not predominant. High fever (over 100°F or 37.8°C) suggests influenza or pneumonia.
6. Other Symptoms:
• Nasal Congestion and Headache: Early-stage symptoms mimicking the common cold.
• Fatigue and Malaise: General feeling of being unwell.
Symptom Duration and Course
• Early Symptoms: The initial days of an acute bronchitis infection may be indistinguishable from the common cold.
• Cough Duration: Patients often underestimate the duration of acute bronchitis-related cough, which can lead to frustration and the unnecessary use of antibiotics.
• Other Symptoms: Besides cough, other signs and symptoms of acute bronchitis include sputum production, dyspnea, nasal congestion, headache, and fever. Patients may have substernal or chest wall pain when coughing.
Differential Diagnosis
Distinguishing acute bronchitis from other respiratory conditions is critical:
1. Pneumonia: High fever, chills, tachypnea, tachycardia, and localized chest pain. Chest radiography often required.
2. Asthma: Recurrent wheezing, shortness of breath, and cough, especially at night or early morning. Pulmonary function tests may reveal reversible airflow obstruction.
3. Chronic Obstructive Pulmonary Disease (COPD): Chronic cough, sputum production, and dyspnea on exertion. Spirometry showing persistent airflow limitation.
4. Pertussis (Whooping Cough): Prolonged cough, paroxysmal cough, whooping sound, and post-tussive vomiting. PCR testing or culture for Bordetella pertussis.
5. Upper Respiratory Tract Infections (URTI): Nasal congestion, sore throat, and mild cough. Typically self-limiting and distinguished based on clinical presentation and shorter duration of symptoms compared to acute bronchitis.
Physical Examination
A thorough physical examination is essential for diagnosing acute bronchitis and ruling out other serious conditions. The examination should include:
1. General Appearance: Assess the patient for signs of distress, fatigue, and overall appearance.
2. Vital Signs: Measure temperature, pulse, respiratory rate, and blood pressure. Fever, tachycardia, and tachypnea may suggest pneumonia rather than bronchitis.
3. Lung Examination: Auscultation may reveal wheezes or rhonchi that typically clear with coughing. The absence of signs of consolidation (e.g., decreased breath sounds, crackles, egophony) can help rule out pneumonia.
4. Chest Wall Tenderness: Palpate the chest wall for tenderness, which can result from severe coughing.
Indications for Chest Radiography
Chest radiography is not routinely required for the diagnosis of acute bronchitis but is indicated under certain circumstances to rule out pneumonia or other serious conditions:
1. Presence of Abnormal Vital Signs:
• Tachycardia: Pulse rate > 100 beats per minute.
• Tachypnea: Respiratory rate > 24 breaths per minute.
• Fever: Oral temperature > 100°F (37.8°C).
2. Suspicious Physical Examination Findings:
• Signs of Lung Consolidation: Decreased breath sounds, bronchial breath sounds, crackles, egophony, and increased tactile fremitus.
• Hypoxia: Low oxygen saturation levels.
3. Patient Risk Factors:
• Age: Elderly patients, particularly those over 75 years, who may present with atypical symptoms.
• Immunocompromised Status: Patients with weakened immune systems or chronic health conditions.
Management
Supportive Care and Symptom Management
Supportive care and symptom management are the mainstays of treatment for acute bronchitis. The role of antibiotics is limited, as emphasized by guidelines from the American College of Chest Physicians and the American Academy of Pediatrics, which recommend against their use unless there is a known pertussis infection.
Over-the-Counter (OTC) Medications
OTC medications are often recommended as first-line treatment for acute cough. However, the evidence supporting their use is limited and of low quality.
1. Cough Suppressants:
• Dextromethorphan: Decreases cough frequency and severity. Evidence from three placebo-controlled trials showed that dextromethorphan decreased cough count by 19% to 36%, equating to 8 to 10 fewer coughing bouts per 30 minutes.
2. Expectorants:
• Guaifenesin: Helps reduce sputum thickness and cough intensity. A Cochrane review found that guaifenesin decreased cough frequency and intensity by 75% at 72 hours compared to 31% in the placebo group.
3. Antitussives:
• Benzonatate: Peripherally acting antitussive that suppresses cough via anesthesia of respiratory stretch receptors. Combining benzonatate with guaifenesin has shown significant improvement in cough symptoms.
4. Analgesics:
• Ibuprofen and Acetaminophen: Used for fever and chest discomfort. A randomized controlled trial showed that compared with placebo, there was no benefit from ibuprofen in decreasing the severity or duration of cough in patients with acute bronchitis. Another randomized controlled trial comparing ibuprofen, acetaminophen, and steam inhalation found that those with a lower respiratory tract infection or age younger than 16 years had a modest reduction in symptom severity when taking ibuprofen over acetaminophen, although the ibuprofen group was more likely to seek care again for new or nonresolving symptoms.
5. Antihistamines:
• Combination with Decongestants: Antihistamines are often used in combination with decongestants in the treatment of acute cough. Two trials of antihistamines alone showed no benefit compared with placebo in relieving cough symptoms. Combination decongestant/antihistamines are more likely to have adverse effects with no to modest improvement in cough symptom scores. In 2008, the U.S. Food and Drug Administration warned against the use of over-the-counter cough medications containing antihistamines and antitussives in young children because of the high risk for harm, and these medications are no longer labeled for use in children younger than four years. They are continuing to investigate the safety of these medications in children up to 11 years of age.
Symptomatic Treatment
Beta2 Agonists:
• Albuterol: Considered for patients with wheezing or airflow obstruction, not recommended for routine use in non-asthmatic patients. Beta2 agonists may provide some benefit in adults with wheezing at the time of evaluation, though evidence is limited.
Non-Pharmacologic Measures:
• Hydration: Encouraged to thin mucus secretions.
• Humidified Air: Use of humidifiers or steam inhalation to soothe the respiratory tract and ease coughing.
• Honey: Effective for children over one year in reducing cough frequency and severity and improving sleep quality.
Avoidance of Antibiotics
Since the majority of acute bronchitis cases are viral, antibiotics should be avoided to prevent adverse effects and antibiotic resistance. Patient education about the natural course of the illness and the limited role of antibiotics is crucial.
Additional Supportive Care
• Analgesics: Acetaminophen or ibuprofen for fever and chest discomfort.
• Corticosteroids: Inhaled corticosteroids for persistent cough, although routine use is not strongly supported by evidence.
Conclusion
Effective management of acute bronchitis centers on accurate diagnosis, patient education, and symptomatic relief while minimizing unnecessary antibiotic use. Adhering to clinical guidelines and promoting informed discussions with patients are essential steps in reducing inappropriate antibiotic prescriptions and enhancing patient care.
References
1. Kinkade, Scott, and Natalie A. Long. “Acute bronchitis.” American family physician 94.7 (2016): 560-565.
2. Wenzel, Richard P., and Alpha A. Fowler III. “Acute bronchitis.” New England journal of medicine 355.20 (2006): 2125-2130.
3. Smith, Susan M., et al. “Antibiotics for acute bronchitis.” Cochrane database of systematic reviews 3 (2014).
4. Dempsey, Patrick P., et al. “Primary care clinicians’ perceptions about antibiotic prescribing for acute bronchitis: a qualitative study.” BMC Family Practice 15.1 (2014): 194.
