Different phenotypes of paediatric and adult airway disease
| Diagnosis | Airway inflammation | Infection | Fixed airflow obstruction | Variable airflow obstruction | Other features | Treatments |
| Year one wheeze [97] | No | Not known, may be acute viral | May be present | May be present, likely bronchospasm, could be malacia, mucus or airway malacia | May occur recurrently Seems likely unrelated to later wheeze, poorly understood | Not ICS Can trial SABA or ipratropium |
| Preschool wheeze | Mostly none, but may be eosinophilic | Acute viral, bacterial or both | Often present | Yes, likely bronchospasm but may be a component of malacia | May occur recurrently | ICS only if evidence of airway eosinophilia Can trial SABA or ipratropium |
| School-age asthma | Usually eosinophilic, but may be pauci-granulocytic | Acute viral, bacterial or both | Often present related to impaired airway development | Yes | Commonly associated with sensitisation to aeroallergens Rhinitis, eczema and food allergy often coexist | ICS if eosinophilic, SABA, LABA, LTRA ?LAMA, AZM for pauci-granulocytic |
| Aspiration syndromes | Neutrophilic | May be bacterial, especially anaerobes | Often acquired | May have bronchospasm May have variable atelectasis | Neuromuscular disease; structural anatomical abnormalities | Treat underlying cause |
| Obesity | May be eosinophilic [87], or IL-6 mediated [88] (systemic inflammation) | Not known | Dysanaptic airway growth [89] | May have bronchospasm May have variable atelectasis | Obstructive sleep apnoea Metabolic syndrome | Weight reduction Ensure there really is an airway disease, not deconditioning ICS only if evidence of airway eosinophilia; can trial SABA or ipratropium |
| Persistent bacterial bronchitis | Neutrophilic | Bacterial, viral | Not well studied, probably not early on | Yes, intraluminal secretions | May occur recurrently Coarse crackles, squeaks and intraluminal mucus often seen in adults (diffuse panbronchiolitis type pattern) | Oral co-amoxiclav for 2 weeks [90]; investigate if no response or relapses Long-term macrolides often highly effective but must exclude an underlying diagnosis [91] |
| CF, PCD, bronchiectasis | Neutrophilic | Bacterial, viral | Yes, often progressive | Yes, intraluminal secretions | May occur recurrently Coarse crackles, squeaks and intraluminal mucus often seen | Antibiotics, airway clearance, see standard guidelines [96] |
| (Chronic) obliterative bronchiolitis | None in chronic phase | None in chronic phase | Yes | No | Associated with autoimmunity in adults (i.e. rheumatoid arthritis) Florid form seen in graft versus host disease | None |
| Chronic bronchiolitis (chILD) | Lymphocytic | None | Not well studied, probably not early on | Not well studied, probably not | Investigate and treat underlying cause, usually an immunodeficiency | |
| Lung disease of prematurity | None unless also atopic [92] | None | Yes, even in late preterm and early term survivors [93] | Yes, bronchodilator reversible [94] | Frequent comorbidities include neurodevelopmental handicap, retinopathy of prematurity, abnormal control of respiration | Bronchodilators as needed, not ICS unless coincidentally atopic |
| Sickle cell anaemia [98] | None | None | Yes | No | Painful and occlusive vascular crises in multiple organs | See standard guidelines, no airway disease treatment unless coincidentally atopic |
| Post NEHI [95] | Probably none | None | Probably, not well studied | Probably, not well studied | Not well studied; not ICS responsive, SABA as needed | |
| Tracheo-bronchomalacia [99] | None | None unless associated with aspiration | None unless associated with a relevant comorbidity | Yes, may be worsened by SABA | Treat underlying cause along standard guidelines and any secondary infection with antibiotics and airway clearance | |
| Adult-onset asthma (most likely adult recrudescence rather than arising de novo) | Highly eosinophilic | Unusual | Can occur | Short-term variable airflow obstruction often not prominent, although airflow obstruction is seen in the context of an attack | Recurrent asthma attacks often the most prominent manifestation Mucus plugging may be a key mechanism for non-bronchodilator airflow obstruction Chronic rhinosinusitis and nasal polyposis commonly seen | ICS Type-2 biologics often highly effective |
| COPD | Variable (all of the above can be seen) | Viral and bacterial | By definition | Can be present | Highly heterogeneous condition, likely related to all of the above; multiple systemic comorbidities associated | Bronchodilators are the mainstay Corticosteroids helpful if evidence of type-2 inflammation |
| Unexplained chronic cough | May be lymphocytic but not well studied | Unusual | No | No | Common in perimenopausal women Heightened cough reflex | No well-established treatments, although P2×3 antagonists look promising |
AZM: azithromycin; chILD: children's interstitial lung disease; ICS: inhaled corticosteroids; IL: interleukin; LABA: long-acting β2-agonist; LAMA: long-acting muscarinic agents; LTRA: leukotriene receptor antagonist; NEHI: neuroendocrine cell hyperplasia of infancy; SABA: short-acting β2-agonist.