Airway calibre, the viruses that circulate, and the diseases that present change with age; the phrase 'difficulty breathing' means bronchiolitis in an infant and asthma in a schoolchild.
6 weeks
Apnea, bronchiolitis, pertussis, and the cardiac lesion that presents as breathlessness.
Differential
Bronchiolitis (coryza, then cough, wheeze and crackles, poor feeding)
Pertussis (paroxysms, apnea, no fever)
Pneumonia
Congenital heart disease presenting with heart failure (sweating with feeds, poor growth)
Sepsis
What changes
Infants under about 3 months with bronchiolitis, especially if premature, are at risk of apnea and are admitted with a low threshold. Ask about feeding, colour changes and pauses in breathing. Examine for a murmur, hepatomegaly and the femoral pulses.
18 months
Croup, the inhaled foreign body, and the first wheeze that may become asthma.
Differential
Viral-induced wheeze
Croup (barking cough, stridor, worse at night)
Foreign body aspiration (sudden onset, unilateral findings)
Pneumonia
Bronchiolitis, less typical at this age
What changes
Distinguish stridor (upper airway, inspiratory) from wheeze (lower airway, expiratory). A sudden cough while eating or playing with small objects is a foreign body until a bronchoscopy says otherwise.
7 years
Asthma severity and the pneumonia behind a persistent fever.
Differential
Asthma exacerbation
Community-acquired pneumonia, including atypical
Viral illness
Anaphylaxis (if sudden with urticaria)
Pneumothorax in the tall thin adolescent-to-be
What changes
Grade the asthma by the ability to speak, the chest movement, the saturation and the response to bronchodilator. A silent chest is severe, not better.
16 years
Adult diagnoses arrive: pneumothorax, pulmonary embolism with risk factors, vaping-related lung injury, and the anxiety diagnosis that must be made last.