Chapter 8:

RESPIRATORY DISORDERS

Student Authors: Lehlohonolo Ntlatlapo and Yandiswa Donkrag

Specialist Advisors: A/Prof. Aneesa Vanker

Illustration showing doctor chasing puff of air

This chapter covers the following topics:

PAEDIATRIC PNEUMONIA/LOWER RESPIRATORY TRACT INFECTIONS (LRTIs)

Pneumonia is an infection of one or both lungs by pathogens including bacteria/mycobacteria, viruses, or fungi. It forms part of a broad spectrum of acute lower respiratory tract illnesses (LRTIs) in children (see a related image here). This terminology recognises that LRTI is a spectrum of illness (ranging from airway to parenchymal disease) which is dependent on the pathogen(s) and the host response.

Pathophysiology

The pneumonia may have an extrinsic (due to exposure to the causative organism) or intrinsic cause (relating to the host e.g. loss of protective reflexes leading to aspiration). When infective, the causative organism finds its way into the lung parenchyma through inhalation or haematogenous spread. The virulence of the organism and the host’s defence mechanisms/immune status determine whether the infected individual will develop pneumonia.

Whatever the cause, the affected patient will have inflammation of the alveoli, which may be filled with fluid or pus. This causes the signs and symptoms of pneumonia, which may include cough, tachypnoea, wheezing.

Aetiology

Causative organisms include:

Clinical Features

The signs and symptoms of pneumonia are often non-specific and vary depending on the child’s age. They include:

Cyanosis may be present in severe cases. Children tend to present with bronchopneumonia and diffuse signs, including hyperinflation, wheezing and crackles. Signs of localised disease include dullness on percussion and bronchial breathing, although this is less common in childhood.

It is most important to observe the child’s respiratory rate. The WHO respiratory rate thresholds for identifying children with pneumonia are:

Table 8.1: WHO Thresholds for Tachypnoea
Age Respiratory rate
Birth - 2 months ≥ 60 breaths/min
2-11 months ≥ 50 breaths/min
12-59 months ≥ 40 breaths/min

According to the WHO, severe/very severe pneumonia should be diagnosed if the child has:

Investigations

One may request the following investigations:

General Management of Pneumonia

The child with signs of excessive work of breathing should immediately be given respiratory support. The type of respiratory support depends on the severity of the distress (watch the oxygen saturation to assess for adequate ventilation and oxygenation). Below are different options for respiratory, which can be used in a step-up or step-down fashion depending on the child’s condition:

Other components of management include:

ASTHMA

See Allergology chapter.

BRONCHIOLITIS

Bronchiolitis is acute inflammation of the bronchioles, usually due to a viral infection (commonly RSV). RSV is highly contagious and spreads via direct contact with nasal secretions, airborne droplets and fomites. Children of any age can present with bronchiolitis but it primarily affects young infants and the most severe symptoms are seen in this age group. Although it is usually seasonal, different viruses cause bronchiolitis during different seasons.

Aetiology

Most cases are due to a viral pathogen with multiple viruses usually being involved. Causative organisms include:

Pathophysiology

The effects of bronchiolar injury are similar to asthma. Viral invasion leads to alveolar cell death and increased mucous secretion and mucous debris. This leads to bronchial obstruction and constriction, air trapping and atelectasis (see related image here). A ventilation-perfusion (V/Q) mismatch is produced due to decreased ventilation and there is resultant increased work of breathing.

Type 1 (IgE-mediated) allergic reaction may account for some clinically significant bronchiolitis. Breastfed infants appear to be more protected against bronchiolitis likely due to the IgA present in breastmilk.

Clinical Features

The child may present with:

If the bronchiolitis is severe, the child may have the following symptoms for >48 hours:

Investigations

Although bronchiolitis is a clinical diagnosis. Investigations may still be necessary to exclude other diagnoses or causes of cough in infants and determine the viral cause.

One may perform:

Management

Non-Pharmacological Management

Conservative management includes:

Non-Pharmacological Management

Conservative management includes:

Pharmacological Management

It is patient-specific and depends on the severity of disease. One may need to prescribe:

ASPIRATION SYNDROME

The causes of aspiration syndromes may be anatomically grouped:

Clinical Features

In patients with GORD, the volume of reflux may be significant enough to cause acute symptoms associated with penetration of gastric contents into the airway. However, there may also be episodes where small amounts of saliva or gastric reflux enter the airway, leading to intermittent or persistent symptoms.

Acute aspiration may be associated with:

If there has been massive aspiration then the child may also have cyanosis and/or pulmonary oedema, resulting in severe respiratory distress syndrome.

Chronic aspiration may be associated with:

Table 8.2: Clinical Features of Aspiration Syndromes
General Symptoms of Aspiration Syndromes General Signs of Aspiration Syndromes
  • Recurrent vomiting
  • Wheezing
  • Noisy breathing
  • Choking, gagging, coughing, and/or spitting during feeds
  • Cyanotic episodes
  • Chest discomfort
  • Recurrent noisy breathing
  • Hoarseness
  • Sore throat
  • Purulent sputum
  • Unexplained fever at night
  • Chronic cough
  • Excessive salivation
  • General examination:
    • Dysmorphisms e.g. cleft palate, micrognathia, macroglossia
    • Fever
    • Clubbing
    • Hypoxaemia
    • Weak suck
    • Hoarse voice or cry and/or irritability
    • Dental erosions
    • Excessive drooling
  • Respiratory examination:
    • Increased work of breathing
    • Added breath sounds (wheezing, crackles, stridor)
    • Noisy breathing
    • Apnoea
  • Congestion
  • Shock
  • Bradycardia

However, the aspiration is sometimes silent and the child does not have any clinical features.

Note: It is important to evaluate for aspiration in asthmatics who have unexplainable nocturnal symptoms, have flares not associated with allergens, URTIs or exercise, or fail to respond to treatment.

Comorbidity

Other conditions which can lead to or are associated with paediatric aspiration syndromes include:

Investigations

The work-up of the child with a suspected aspiration syndrome includes:

Lab studies Imaging studies Procedures Histological
  • FBC
  • Pulse oximeter
  • Sweat chloride
  • Lung function test
  • Skin-prick test (SPT) for allergen-specific serum Ige (if eosinophilic esophagitis is being considered)
  • Chest X-ray – may show hyperinflation, uni- or bilateral diffuse interstitial or perihilar infiltrates, peribronchial thickening, pleural effusion, lobar or segmental consolidation, bronchiectasis or atelectasis
  • Barium swallow/ contrast swallow (to assess for anatomical or physiological abnormalities of the upper GIT)
  • Radio-isotope “milk” scan (to assess the severity of the reflux and risk of aspiration)
  • Oesophageal pH (24-hour monitoring for acid reflux)
  • Multi-channel intraluminal impedance and pH monitoring (for acid and non-acid reflux)
  • Oesophagogastro-duodenoscopy with biopsies (to assess for eosinophilia, distal oesophageal erythema, erosions, ulcers, and mucosal friability)
  • Immunocytochemical staining of alveolar microphages for milk proteins
 Bronchoscopy (bronchoalveolar lavage fluid will show lipid-laden macrophages

Management

A multidisciplinary approach is required. Management options may be divided into medical and surgical interventions.

Medical Interventions

They include:

Surgical Interventions

One may perform:

FOREIGN BODY ASPIRATION

It is most common in children <3 years old. Children are more prone to aspirating foreign bodies for several reasons:

Clinical Features

The child may present with a history of sudden coughing or choking while eating or playing.

The choking episode is often not witnessed or recalled by the carer. Children with unwitnessed aspiration may present with:

If the foreign body (see image here) is in the subglottic space, the child may have stridor, recurrent or persistent croup, or haemoptysis. Total or near-total occlusion of the airway may occur, leading to death or hypoxic brain damage.

Investigations

One should request:

Note: All children with suspected foreign body aspiration require bronchoscopy to exclude the diagnosis, even if they do not have any clinical signs.

Management

First aid for the patient with an obstructed airway should be performed (Heimlich manoeuvre). Endoscopy should be performed and the foreign body removed with a rigid bronchoscopy (if identified).

PNEUMOTHORAX

It is an abnormal collection of air in the pleural space (potential space between the mesothelial membranes covering the lungs and chest wall).

Pathophysiology

It occurs when air leaks into the pleural space, pushing the lung and causing it to collapse. This leak may happen suddenly or develop slowly. The severity of the pneumothorax depends on where the leak occurs, how quickly it develops, the amount of air leaking, the extent of lung collapse and the underlying clinical status of the patient. Paediatric pneumothoraces are uncommon but can be life threatening.

Loss of intrapleural negative pressure following a spontaneous pneumothorax (rupture of visceral pleura) or traumatic pneumothorax (rupture of either pleura) causes the lung(s) to collapse. This decreases the patient’s vital capacity and leads to a decrease in arterial oxygen partial pressure; see related image to pneumothorax here.

Classification and Aetiology

There are four types of paediatric pneumothoraces:

Pneumothoraces can be further classified as:

The prognosis is excellent in the patient with an isolated pneumothorax that is diagnosed and treated early.

There is a risk of recurrence. The risk is highest in those with secondary or spontaneous pneumothoraces and in patients who participate in activities such as deep-sea diving.

Clinical Features

A simple pneumothorax may be asymptomatic. The symptomatic patient may present with:

Babies may present with non-specific signs and symptoms, such as irritability, restlessness, tachypnoea, grunting, nasal flaring, retractions, anaemia and cyanosis.

The patient with a tension pneumothorax may be shocked (tachycardic and hypotensive), display excessive work of breathing and/or have tracheal deviation towards the unaffected side.

Investigations

A pneumothorax (especially a tension pneumothorax) is a clinical diagnosis. A chest X-ray should only be performed if the patient is stable and can be used to confirm the diagnosis.

Management

If the patient has a simple, asymptomatic pneumothorax, s/he may be conservatively treated with 100% oxygen via a non-rebreather face mask (give for a short period to avoid oxygen toxicity). As the leak seals, the trapped air is absorbed.

A simple, traumatic pneumothorax should be managed with an intercostal drain (ICD) because there is a high risk of a tension pneumothorax developing (especially if the patient is given PPV.

A large or significantly symptomatic pneumothorax should be managed with an ICD, administration of 100% supplemental oxygen and appropriate pain management. In an emergency, the air may also be removed by needle decompression (with a syringe attached to suction out the air). This should be followed by the insertion of an ICD.

PLUERAL EFFUSION

A pleural effusion is an abnormal collection of fluid in the pleural space.

Pleural effusions develop because of excessive filtration of fluid into the pleural space or defective absorption of pleural fluid. They may be primary manifestations or secondary complications of many disorders.

Mechanisms by which pleural effusions occur include:

Clinical Features

The child’s presentation depends on the aetiology (underlying disease), size and location of the effusion. S/he may present with:

Investigations

They should include:

Light’s Criteria is used to differentiate a transudative effusion from an exudative one.

Table 8.3: Light's Criteria
Light's Criteria
CRITERIA
 TRANSUDATE EXUDATE
Pleural fluid:serum protein ratio ≤0.5 >0.5
Pleural fluid LDH:serum LDH ≤0.6 >0.6
Pleural fluid LDH ≤200 >200

Management

One must treat the underlying cause and provide respiratory support if the child has signs of increased work of breathing.

Indications for chest tube drainage include:

Children with parapneumonic effusions or empyema should be followed up within 4–6 weeks of discharge.

EMPYEMA

It is a type of pleural effusion which is characterised by a collection of pus in the pleural space. It is most commonly caused by a bacterial infection and often requires extensive therapy, is associated with longer hospital stays and has high morbidity rates. An empyema often develops in the context of pneumonia, a lung abscess, bronchiectasis, injury or post-thoracic surgery of/on the ipsilateral lung. It is the most common pleural effusion seen in paediatric patients.

Pathophysiology

An empyema develops because of:

Infective Pleural Effusions

The pleural space normally contains small volumes of transudative fluid with protein (<1.5 g/dL), lymphocytes, microphages and mesothelial cells but no neutrophils. The gradual development of an empyema may be divided into three stages.

After appropriate and adequate treatment, the inflammatory cellular and cytokine production declines and there is no longer a neutrophil predominance in the parapneumonic effusion (with resolution of the inflammation, the influx of macrophages helps to clear the neutrophils). Migration of mesothelial cells to areas of stripped pleura leads to re-epithelialisation and recovery of normal function. On the contrary, following severe pleural inflammation, there is an increased potential for fibrosis and restrictive lung disease.

Aetiology

In paediatrics, the most commonly implicated organisms are S pneumoniae, S aureus, and group A streptococci. There may also be anaerobic infections secondary to aspiration, or fungal or mycobacterial infections in immunosuppressed patients. NSAIDs are associated with an increased risk of empyema in children.

Clinical Features

Most patients present with clinical features suggestive of bacterial pneumonia:

The child may be cyanosed, and may have abdominal pain and vomiting because of the inflammation of the pleural space (see related diagram here). The latter four signs may be difficult to elicit in a younger child because of discomfort they are experiencing and the fact that they are often less cooperative.

Investigations

They should include:

Management

It should include:

Fibrinolytics may be instilled into the pleural space to break down loculations. Surgical intervention may be considered for complicated cases with adhesions.

Note: An empyema is an advanced type of parapneumonic effusion. Other types include uncomplicated parapneumonic effusion (neutrophil effusion) and complicated parapneumonic effusion. The latter requires thoracentesis, tube thoracostomy or surgery.

CROUP/LARYNGOTRACHEOBRONCHITIS

Croup is an infection and inflammation of the larynx, trachea and bronchial airways. It is contagious, especially during the first few days.

Aetiology

It is commonly due to viral infection:

It is less commonly due to bacterial infection (Corynebacterium diphtheriae, S. aureus, S. pneumoniae, H. influenzae and M. catarrhalis). Bacterial infection can be primary or may be secondary to viral infection.

Clinical Features

They often begin as a typical cold (fever and runny nose) and are characterised by:

Symptoms often start or are worse at night and normally last for 1-2 days. Breathing difficulties are of major concern.

Investigations

Before croup can be diagnosed, epiglottitis and foreign body aspiration must have first been excluded. Further investigations are not usually needed. However, an X-ray may show the characteristic steeple sign (see a related image here).

Grading and Management

The management will depend on the severity of the croup.

Table 8.4: Severity and Management of Croup
Severity Inspiratory Stridor Expiratory Stridor Pulsus Paradoxus Management
Grade 1 + - -
  • Provide supportive care
  • Give nebulised adrenaline
  • Avoid crying,
  • Give systemic steroids (oral prednisone 2 mg/kg)
  • Give supplemental oxygen
  • Give continuous nebulised adrenaline
  • Give systemic steroids (oral prednisone 2 mg/kg or IV dexamethasone 0.6mg/kg)
  • Sedate as needed
    		•
    Grade 2 + Passive -
    Grade 3 + Active +
    Grade 4 Same as grade 3 plus marked retraction, apathy and cyanosis
  • Urgent intubation
    		•

    Antimicrobials may also be given based on the suspected causative organism:

    Many cases of croup may be prevented with influenza and diphtheria immunisations.

    Note: Corticosteroids (e.g. dexamethasone, prednisone, budesonide) decrease swelling and the need for salvage nebulised epinephrine.

    BRONCHIECTASIS

    It is the dilatation of bronchi secondary to destruction of the elastic and muscular components of their walls.

    Pathophysiology

    Obstruction and/or inflammation of the airway (from a previous insult, most commonly an infection) causes airflow limitation, abnormal quality and quantity of mucous and ciliary dyskinesia. This leads to reduced mucous clearing and increased bacterial colonisation and infection. Thus, there is a vicious cycle of infection and dysregulated airway inflammation, resulting in the progressive destruction of bronchial walls, bronchial dilatation and airflow obstruction. Bronchiectasis is, therefore, the result of interactions between the host, pathogens and the environment (see also related image here).

    Aetiology

    Bronchiectasis may be caused by:

    Clinical Features

    Bronchiectasis is often localised and produces recurrent cough and infectious exacerbations. However, when it is diffuse the patient will often have additional signs and symptoms of generalised airway obstruction and reduced lung function (which may lead to respiratory failure). These features include:

    Complications of bronchiectasis include atelectasis and life-threatening haemoptysis.

    Investigations

    The following investigations may be done to look for the underlying cause:

    Management

    It should include: