Figure 3: Proportion of children with symptoms of bronchiolitis
those children with chronic cough that might require further investigations. Clearly, there is a ‘grey’ area between acute cough (up to four weeks) and chronic cough (over eight weeks), sometimes called ‘subacute cough’. An example of such a situation would be a child with pertussis or post-viral cough whose cough may be slowly resolving over a three-to-eight week period. If a cough is resolving, an additional period of time may be required to elapse before performing further investigations. However, if the cough is not waning by the third week and is becoming more severe in frequency and intensity (‘relentlessly progressive’), earlier investigations may be warranted (see Figure 2). Is it worth determining if a cough is wet or dry? A cough that is wet or productive implies either an increase in airway secretions or abnormalities in its clearance mechanisms. Young children tend not to expectorate sputum and so it is important to hear the cough yourself. Children with isolated dry cough and who appear otherwise well with normal chest x-ray appearance may have asthma, gastro-oesophageal reflux, pertussis, allergic rhinitis, mycoplasma or habit-related cough. However, an isolated dry cough, without wheeze or breathlessness, is rarely due to asthma. The diagnosis of asthma requires the presence of symptoms (more than one) of wheeze, breathlessness, chest tightness or cough. Children with persistent, productive (moist or wet) cough should be investigated to determine if they have bronchiectasis or any of the specific suppurative lung conditions which lead to bronchiectasis, ie, persistent bacterial bronchitis, inhaled foreign body/recurrent aspiration, cystic fibrosis, TB or interstitial lung disease.
Persistent bacterial bronchitis Several studies have identified persistent bacterial bronchi-
tis (PBB) as the most common cause of chronic wet cough in children. PBB is characterised by an isolated chronic wet or productive cough without signs of another cause, and usually responds to two weeks of an appropriate oral antibiotic (oral amoxicillin–clavulanic acid) if diagnosed early in the course of the condition. Later diagnosis may require a four-week course of antibiotics. The aim of treatment is to both eradicate bacteria colonisation and allow regeneration of the endobronchial epithelium. Typically, children with PBB are young — the majority of related studies involve children less than six years old. Chest x-ray may have only minor abnormalities, such as ‘peribronchial wall thickening’, and hyperinflation is uncommon. If left untreated, PBB may develop into chronic suppurative lung disease in some children and possibly bronchiectasis. PBB is often misdiagnosed as bronchial asthma or bronchial pneumonia, because doctors lack awareness of the disease. It is unusual that the definition of PBB includes the response to treatment. The initial definition also included the presence of a respiratory bacterial pathogen on bronchoalveolar lavage. Clearly, these children do not all need bronchoscopy and so the need for bronchoalveolar lavage has been dropped from the definition. It is also not necessary at present to identify the lung pathogen prior to diagnosis and treatment, which is certainly causing concern in some quarters. So PBB is an important cause of chronic wet cough among children. While we have an ethical responsibility to prescribe antibiotics appropriately (and inappropriate use of antibiotics should at all times be discouraged), we also have a duty of care to identify conditions such as PBB, which respond to antibiotic treatment. Inappropriate treatment due to failure to make an accurate diagnosis leading to unnecessary morbidity, and in this case bronchiectasis, is also unacceptable.
Summary In summary, cough is a forced expulsive manoeuvre, usually against a closed glottis and which is associated with a characteristic sound. Identifying the diagnosis-causing cough can be guided by considering the duration and whether the cough is wet or dry. An acute dry cough in a well child, with a normal examination, may last up to three weeks and does not need further investigation or antibiotic treatment. An isolated dry cough, without wheeze or breathlessness, is rarely due to asthma. The diagnosis of asthma requires the presence of symptoms (more than one) of wheeze, breathlessness, chest tightness or cough. Persistent bacterial bronchitis is a common cause of chronic wet cough in children and responds to two-to-four weeks of antibiotic treatment. The Irish Primary Care Respiratory Society is hosting the International Primary Care Respiratory Group meeting in May 2020 in Dublin. The group is open to new members, including but not limited to community pharmacists, nurses, physiotherapists and GPs in training. Please contact the author for more details: firstname.lastname@example.org.
Clinical Journal for all healthcare professionals specialising in, or with an interest in, respiratory medicine