acute_bronchitis_flashcards (1)
Definition
Acute bronchitis is a type of lower respiratory tract infection where there is inflammation of the large airways but not of the lung parenchyma (i.e. not a pneumonia). Cough is the predominant clinical feature, and the majority of cases are mild and self limiting.
Epidemiology
Acute bronchitis is common, with approximately 5% of adults per year affected. Cases are higher in the autumn and winter months. Smoking is an important risk factor.
Aetiology
The majority of cases are viral, with common causes including: Rhinovirus, Coronavirus, Adenovirus, Respiratory syncytial virus (RSV), Influenza A and B, Parainfluenza. Bacteria may be responsible in 1-10% of cases, including: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, Bordetella pertussis.
Signs and Symptoms
Cough is the main symptom, which may be dry or productive. Patients may report initial upper respiratory tract symptoms (e.g. headache, coryza, sore throat) that may overlap with lower respiratory tract symptoms. Other symptoms may include mild dyspnoea, chest wall pain with coughing, fatigue, malaise. Signs may include low-grade fever, wheeze (especially on forced expiration), and rhonchi that clear with coughing.
Differential Diagnosis
Pneumonia should be suspected in patients who are unwell with features including focal chest signs, hypoxia, tachypnoea, tachycardia, and fevers - a chest X-ray showing consolidation is the key differentiating investigation. Other differential diagnoses include chronic obstructive pulmonary disease, acute asthma exacerbation, pulmonary embolism, postnasal drip, ACE inhibitor-induced cough, and lung cancer with specific characteristic symptoms.
Investigations
The diagnosis of acute bronchitis is clinical, and in the majority of cases no investigations are required. If there is diagnostic uncertainty, respiratory viral swabs, sputum culture, CRP, and chest X-ray may be considered to rule out other conditions.
Management
Conservative management includes reassurance, fluid intake, self-care measures like lozenges or honey, and smoking cessation. Safety net advice to seek medical help if symptoms worsen or persist. Medical management may involve paracetamol for pain/fever. Antibiotics are rarely needed and reserved for high-risk cases, with doxycycline as first-line if required.
Complications
Pneumonia may complicate acute bronchitis, especially in vulnerable patients due to older age, frailty, comorbidities, or immunosuppression. Persistent cough lasting over a month occurs in 25% of patients and may persist for up to 6 months in some cases.
Prognosis
The majority of patients recover fully within 2-3 weeks. Recurrence is common, especially in patients who smoke.
