Differentials
Inhaled foreign body
SIGNS / SYMPTOMS
Sudden onset of symptoms, such as cough, wheeze, or choking.
Auscultation reveals differential air entry or wheeze.
INVESTIGATIONS
Inspiratory and expiratory chest x-rays may reveal asymmetry of chest expansion, due to the ball-valve mechanism of the foreign body.
Bronchoscopy is necessary for diagnosis and retrieval of the foreign body.
Viral-induced infantile wheezing
SIGNS / SYMPTOMS
Onset in infancy. No associated atopy.
Associated with maternal smoking.
Diagnosis usually made retrospectively once the child has left the infantile age range.
INVESTIGATIONS
Skin prick testing is negative; may provide supportive evidence but is not definitive.
Aspiration
SIGNS / SYMPTOMS
History of vomiting and/or history of choking or coughing during swallowing (in particular, when neurodevelopmental abnormality is present).
Focal signs of pneumonitis or pneumonia may be present on examination.
INVESTIGATIONS
Focal signs of pneumonitis or pneumonia on chest x-ray.
Modified barium swallow may confirm diagnosis.
Anaphylaxis
SIGNS / SYMPTOMS
Acute anaphylaxis may present with associated respiratory distress and wheeze. Urticaria and signs of upper airway obstruction may be present.
History of environmental exposure to a possible or known anaphylactic stimulus.
INVESTIGATIONS
Clinical diagnosis.
Cardiac failure
SIGNS / SYMPTOMS
Other features of cardiac failure are present (tachycardia, gallop rhythm, or hepatomegaly).
Associated with congenital or acquired heart disease.
INVESTIGATIONS
Cardiomegaly on chest x-ray.
Congenital heart disease and impaired cardiac function are demonstrated on an echocardiogram.
Pneumonia
SIGNS / SYMPTOMS
Focal signs may be present on examination and include crepitations, decreased air entry, bronchial breathing, and dull percussion note.
INVESTIGATIONS
Consolidation on chest x-ray.
Raised WBC count.
Pneumothorax
SIGNS / SYMPTOMS
Sudden onset of chest pain or dyspnoea.
Larger pneumothoraces may have signs of decreased air entry and hyper-resonant percussion note on examination.
No wheeze on auscultation.
May complicate an asthma exacerbation.
INVESTIGATIONS
Pneumothorax is seen on chest x-ray.
Pertussis
SIGNS / SYMPTOMS
Infection with Bordetella pertussis causes prolonged coughing (also called the '100-day cough').
Spasmodic coughing may lead to post-tussive emesis.
Characteristic whoop may not be evident in younger children.
INVESTIGATIONS
Pertussis polymerase chain reaction on nasal swab sample.
Optimal sensitivity during the first 3 weeks of cough.[65]
Absolute lymphocytosis of WBC differential may be present.
Cystic fibrosis (CF)
SIGNS / SYMPTOMS
Airway inflammation associated with CF may precipitate wheeze, cough, and respiratory distress.
CF due to milder mutations may present with asthma that is difficult to control or treatment-resistant.
Asthma may co-exist with CF.
Failure to thrive may be present.
INVESTIGATIONS
Sweat test: in children with a positive newborn screen, clinical features consistent with CF, or a positive family history, CF can be diagnosed if sweat chloride ≥60 mmol/L (levels of 30-59 mmol/L are intermediate and may warrant genetic testing).[66]
Bronchiectasis
SIGNS / SYMPTOMS
Airway inflammation associated with bronchiectasis may precipitate wheeze, cough, and respiratory distress.
Asthma may co-exist with bronchiectasis.
INVESTIGATIONS
Chest CT scan to diagnose bronchiectasis.[67]
Tracheo- or bronchomalacia
SIGNS / SYMPTOMS
Characterised by expiratory stridor.
Recurrent acute episodes of stridor and dyspnoea usually present in the neonatal period and diminish during the first 2 years of life.
INVESTIGATIONS
Bronchoscopy reveals collapse of the trachea or bronchus during expiration.
Acute bronchitis
SIGNS / SYMPTOMS
Characterised by moist cough in combination with wheeze, and may be caused by bacterial or viral infection.
Bacterial cause is suggested by purulent sputum and response to antibiotics.
INVESTIGATIONS
In bacterial bronchitis, sputum culture commonly isolates Haemophilus influenzae or Streptococcus pneumoniae.[68]
Paradoxical vocal cord motion or vocal cord dysfunction
SIGNS / SYMPTOMS
Paradoxical adduction of the vocal cords during inspiration produces high-pitched inspiratory stridor and dyspnoea that may be misinterpreted as wheeze.
May be spontaneous or exercise-induced.
INVESTIGATIONS
Exercise testing may reproduce the characteristic symptoms.
Spirometry during an episode demonstrates blunting of inspiratory volume loop.
Hyperventilation attack
SIGNS / SYMPTOMS
No associated wheeze on auscultation.
INVESTIGATIONS
No obstructive pattern on spirometry during a hyperventilation episode.
Exertional dyspnoea unrelated to pathology
SIGNS / SYMPTOMS
Perception of breathlessness during exercise alone.
INVESTIGATIONS
Exercise testing may help distinguish.
Croup
SIGNS / SYMPTOMS
Characteristic sudden onset, barky cough, often accompanied by stridor and chest wall or sternal indrawing.
No associated wheeze on auscultation.
INVESTIGATIONS
Clinical diagnosis.
Metabolic acidosis
SIGNS / SYMPTOMS
Tachypnoea in response to various causes of metabolic acidosis, such as diabetic ketoacidosis.
Wheeze is absent.
INVESTIGATIONS
Blood gas. Other clinical features depend on cause of metabolic acidosis.
Allergic bronchopulmonary aspergillosis (ABPA)
SIGNS / SYMPTOMS
Usually insidious onset presenting with chronic productive cough and wheezing. Other symptoms include pleuritic chest pain, and haemoptysis; golden-brownish mucous plugs in sputum is a characteristic finding in ABPA. Most commonly described in children with cystic fibrosis (CF), but also known to rarely occur in children with asthma without CF.[69]
INVESTIGATIONS
Sputum showing Aspergillus fumigatus and blood indices showing elevated immunoglobulin E and precipitating antibodies to A fumigatus.[70]
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