Cough, cough… who’s there?

Dr Nick Flynn provides a clinical overview of the various presentations of cough in the clinic

November is a tough month in general practice. The summer is a distant memory, the annual flu vaccination campaign is in full flight and circulating cold and flu viruses are testing capacity in daytime and out-of-hours services. November does, however, have its saving graces. There’s the Cork Film Festival, the autumn rugby internationals and for the last three years, the Irish Primary Care Respiratory Society has held its AGM in November. Normally, the meeting provides a timely reminder of the spike in respiratory presentations we see during the winter period and the most recent meeting was no different. There were presentations on asthma, asthma deaths in Ireland, COPD, and then there was Dr Reggie Spellman presenting on cough in children. Dr Spellman is the President of the Irish Primary Care Respiratory Society and throughout his career has promoted excellence in respiratory medicine in general practice. Like all good presentations, Dr Spellman’s was simple, informative and thought-provoking.

All children cough at some stage. Respiratory tract infections in children are responsible for more GP consultations than any other group of illnesses. In most cases, these are self-limiting conditions and the risk of complications is small. Many children with head colds and respiratory tract infections present to their GP because of concern around the associated symptom of cough. Recommended management typically involves parental education regarding self-care and treatment of symptoms.

In order to empower parents fully in this regard, we do need to inform them how long symptoms relating to a particular self-limiting condition are likely to last. Accurate information about the expected duration of symptoms in children is essential for both parents and doctors, as it establishes parental expectations and informs them when the condition is deviating from the expected course.

Symptom duration

In December 2013’s British Medical Journal, Thompson et al published a systematic review of existing literature to determine durations of symptoms of earache, sore throat, cough (including acute cough, bronchiolitis and croup), and the common cold in children. Helpfully, the authors presented their results as the number of days it took for 50 per cent and 90 per cent of the children’s symptoms to have resolved. It is reasonable to interpret these values into absolute terms as the time for half the children to get better and the time for nine-out-of-10 children to get better. This information can be used to direct more appropriate help-seeking behaviours by parents and use of antibiotics by doctors.

The results showed that in 90 per cent of children, earache was resolved by seven days, sore throat resolved in two-to-seven days and acute cough resolved within three weeks (see Table 1). Acute cough had resolved in 50 per cent of children at 10 days, and in 90 per cent of children by 25 days. It would be helpful for each practice and out-of-hours co-operative to have agreed protocols on how long symptoms will last to guide help-seeking behaviour and antibiotic use (see Figure 1).

The majority of children with acute cough have a viral respiratory tract infection. An attempt should be made to arrive at a specific clinical diagnosis. The absence of fever, tachypnoea and chest signs appear to be most useful indicators for ruling out future complications in children with cough in the community. Consideration should be given to potential other diagnoses, including pneumonia, an inhaled foreign body and allergy. However, 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.

Bronchiolitis

Bronchiolitis is a common cause of acute dry cough and is the most common respiratory tract infection seen in children under one year of age. The peak incidence is between three and six months of age, occurring in particular between the months of November and May. The underlying pathophysiology is inflammation of the small airways (bronchioles).

Bronchiolitis is a highly-infectious viral illness and most cases are caused by the respiratory syncytial virus (RSV), although some cases are also caused by other viruses (rhinovirus, parainfluenza virus, adenovirus and influenza viruses). By age three years, virtually all children have serological evidence of RSV infection. Unfortunately, infection does not produce protective immunity, so reinfection is common.

A UK Delphic process reached a 90 per cent consensus that bronchiolitis “is a seasonal viral illness, characterised by fever, nasal discharge and dry, wheezy cough. On examination, there are fine inspiratory crackles and/or high-pitched expiratory wheeze”.  Bronchiolitis typically begins with an upper respiratory tract infection manifested by fever and coryza. After two-to-three days, the lower respiratory tract involvement becomes obvious, with worsening cough and shortness of breath. Apnoea is a frequent complication and may occur in up to 20 per cent of cases, particularly in premature infants. Clinical examination findings include increased respiratory effort, wheezing and fine crackles on auscultation, and dehydration. Most infants show signs of improvement within three-to-four days after the onset of lower respiratory tract disease (see Figures 2 and 3).

Acute bronchiolitis is a clinical diagnosis and therefore clinical history and physical examination are the most important diagnostic steps. Pulse oximetry should be performed if hypoxia is suspected. Otherwise in the community setting, the infant with typical acute bronchiolitis requires no investigations. Specifically, chest x-ray is not useful and may lead to the unnecessary prescription of antibiotics.

There are environmental risk factors that predispose to bronchiolitis infection, including poverty, overcrowding, damp living conditions, parental smoking and malnutrition. There are also factors which predispose certain children to more severe disease and lower the threshold for hospital referral, including surviving preterm infants, young age (less than six weeks), Down syndrome, congenital heart disease, chronic respiratory disease (ie, cystic fibrosis), and social factors (ie, concern about the family’s ability to notice and respond to worsening of the condition).

The management of bronchiolitis in general practice is supportive and focused on providing information and coping skills to parents. It is important to give appropriate advice regarding the likely duration of the illness, managing pyrexia, hydration, feeding and avoidance of smoking. It is also important that parents are aware of signs that the illness is deviating from the normal self-limiting course, ie, tachypnoea, recurrent vomiting, dry nappies, pallor, cyanosis, etc.

As there is no specific treatment, the indications for admission would be diagnostic uncertainty, the need for oxygen, or the need for tube feeding/rehydration. Clearly, cyanosis or really severe respiratory distress (respiratory rate >70 breaths/min, nasal flaring and/or grunting, severe chest wall recession), marked lethargy leading to poor feeding or apnoeic episodes would all precipitate hospital referral.

Otitis media is frequently seen in association with RSV bronchiolitis. However, serious bacterial infection rarely accompanies RSV bronchiolitis. Routine antibiotic treatment does not improve the recovery of infants with RSV lower respiratory infection.

Chronic cough

Once a cough has persisted beyond eight weeks, it is regarded as a chronic cough. The main reason to classify cough on this time basis is that three-to-four weeks allows most simple infective causes of cough to have resolved and identifies 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 bronchitis (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: nickflynngp@gmail.com.