LRTI in Children

Synonyms: Chest infection, bronchitis, bronchiolitis, pneumonia, LRTI

Lower respiratory tract infection (LRTI) is infection below the level of the larynx and may be taken to include:

• Bronchiolitis¹
• Bronchitis
• Pneumonia
• Laryngotracheobronchitis (croup)

The presentation of these conditions will depend on age, infecting organism and site of infection. Laryngotracheobronchitis is considered separately.

Epidemiological data is poor because accurate diagnosis is limited by diagnostic methodology.

• The incidence of LRTI is 30 per 1000 children per year in the UK.
• Every year, pneumonia contributes to between 750,000 and 1.2 million neonatal deaths worldwide and an unknown number of stillbirths.²
• In 1990, the WHO estimated that LRTI in children (60% due to S. pneumoniae or H. influenzae) caused 4.3 million child deaths worldwide. A WHO study in 2004 cited clinical pneumonia (principally pneumonia and bronchiolitis) in children under 5 years old as the leading cause of childhood mortality in the world.³ It is estimated that 95% of such infections occur in developing countries.³
• H. influenzae infection is now quite rare amongst UK children because of immunisation.
• Deaths from pneumonia in the UK decreased from >600 in 1980 to <100 by 1995.

There is no hard and fast definition of lower respiratory tract infection (LRTI), that is universally agreed upon. Essentially, it is inflammation of the airways/pulmonary tissue, due to viral or bacterial infection, below the level of the larynx. Remember that gastrooesophageal reflux may cause a chemical pneumonitis. Smoke and chemical inhalation may also cause pulmonary inflammation.

• Viral infections.⁴ About 45% of children hospitalised with pneumonia have a viral aetiology.⁵ These include:
  • Influenza A
  • Respiratory Syncytial Virus (RSV)⁶
  • Human Metapneumovirus⁴
  • Varicella-Zoster Virus (VZV - chickenpox)
• Bacterial infection. These constitute about 60% of hospitalised pneumonia cases:⁵
  • S. pneumoniae (about 73% of bacterial pneumonias⁵)
  • H. influenzae
  • S. aureus
  • Klebsiella pneumoniae
  • Enterobacteria eg E. coli
  • Anaerobes
• Atypical organisms ie Mycoplasma (14% of all cases of hospitalised pneumonia in children⁵), Legionella pneumophila, Chlamydia spp.(9% of hospitalised pneumonia in children⁵), Coxiella burnetii.
• Secondary bacterial infection is relatively common following viral upper respiratory tract infection (URTI) or LRTI. Primary bacterial infection with a range of organisms occurs.Current debate about true primary and secondary infection, where there is concomitant viral and bacterial illness, is unlikely to be resolved. In one study 23% of children admitted to hospital with pneumonia had mixed bacterial and viral infections.⁵

Most often LRTI is accompanied by fever and may be preceded by a typical viral URTI. It is important to assess all children with a fever accurately. Recent NICE guidance on the management of feverish illness in children has been produced.⁷ Essentially dyspnoea (without wheeze) and fever in a child should suggest LRTI. However, this is not a straightforward association as any child with a fever may increase their respiratory rate (because of poor oxygen reserve and the metabolic demands of any infection).
In all age groups be aware that:

• Audible wheezing is not seen very often in LRTI (although it is common with more diffuse infections such as in Mycoplasma and bronchiolitis).
• Stridor or croup suggests URTI, epiglottitis or foreign body inhalation.

History

Age, and the type of LRTI will affect the symptoms and history.

Examination

• General points:
  • Examination can be difficult in young children (particularly auscultation).
  • A careful routine of observation is essential to identify respiratory distress early.
  • Pulse oximetry can be very useful in evaluation. Typically in pneumonia for example, oxygen saturation may be 95% or less.
  • High fever over 38.5 °C may occur often. However it is important not to ascribe too much significance to level of fever.⁷
  • Look for other diseases (for example rashes, pharyngitis) with careful systematic examination.

  The following should alert to respiratory distress: Cyanosis in severe cases. Grunting. Nasal flaring. in children under 12 months can be a useful indicator of pneumonia.8,7 Marked tachypnoea (see below). Chest indrawing (Intercostal and supra-sternal recession).7 Other signs such as subcostal recession, abdominal 'see-saw' breathing and tripod positioning. Reduced oxygen saturation (less than 95%). If this does not respond to oxygen and general support of the child's own respiratory effort, intubation is likely to be required. Intubation is required when the child's own breathing becomes ineffective (with, for example, hypoxia, rising carbon dioxide and reduced level of consciousness).

• Observation:
  • Further careful observation in good light, with the chest and abdomen uncovered is essential.
  • Count respirations and note respiratory rate (RR in breaths per minute).
    Tachypnoea is measured as:⁷
    • Respiratory rate (RR) >60/ minute age 0 to 5 months
    • RR >50/ minute age 6 to 12 months
    • RR >40/ minute age over 12 months
  • Observe infants feeding (to uncover decompensation during feeding).
  • Observe chest movements (for example looking for splinting of the diaphragm).
• Auscultation:
  • Examine with warm hands and stethoscope.
  • Take the opportunity to examine a quiet sleeping child.
  • Concomitant upper respiratory noises can be identified by listening at the nose and chest.
  • Crackles and fever indicate pneumonia.
  • Crackles in the chest may indicate pneumonia particularly when accompanied by fever.⁷
• Percussion:
  • Identifies consolidation.
  • Consolidation is a later and less common finding than the crackles of a pneumonia.
  • Later on in older children there may be dullness to percussion over zones of pneumonic consolidation.
  • Bronchial breathing and signs of effusion occur late in children and localisation of consolidation can be difficult to diagnose.

• Asthma
• Inhaled foreign body
• Pneumothorax
• Cardiac dyspnoea
• Pneumonitis from other causes:
  • Extrinsic allergic alveolitis
  • Smoke inhalation
  • Gastrooesophageal reflux

• General points:
  • Few tests are particularly useful or required.
  • The most useful tests give quick and meaningful results.
• Full blood count:
  • White cell count is often elevated. Although this may be very noteworthy in certain infections (like pneumococcal pneumonia) it is useful only as a general guide to the presence of infection.
  • It is important in very ill children who may be immunocompromised.
• Microbiological studies:
  • Rarely indicated or of help in general practice.
  • Blood cultures are seldom positive in pneumonia (less than 10% are bacteraemic in pneumococcal disease).
  • Blood and sputum cultures should generally be reserved for atypical or very ill patients (particularly those who may be immunocompromised).
• Imaging:
  • Chest radiography (CXR) if fever and tachypnoea is indicated.
  • CXR cannot differentiate reliably between bacterial and viral infections.
• Other tests:
  • Tuberculin skin testing if tuberculosis suspected.
  • Cold agglutinins when mycoplasmal infection suspected (but only 50% sensitive and specific).
  • Urine latex agglutination tests may ultimately diagnose certain organisms but the tests take time and are rarely of use acutely.
• Diagnostic procedures:
  • Drainage and culture of pleural effusions may relieve symptoms and identify the infection.

• General:
  • Admission for children under 5 years with fever and breathlessness should be considered. Mild bronchiolitis can be managed at home with close observation.
  • Indications for admission also include:
    • All children under 6 months
    • Immunocompromised children
    • Toxic children
    • Children in whom treatment with antibiotics has failed (most children improve after 48 hours of oral, outpatient antibiotics)
    • Patients with troublesome pleuritic pain
  • Older children can be managed with close observation at home if not distressed or significantly dyspnoeic, and parents can cope with the illness.
  • Most children with LRTI and pneumonia can be treated as outpatients with oral antibiotics. Viral bronchitis and croup do not require antibiotics and mild cases can be treated at home.
  • Physiotherapy has no place in treatment of uncomplicated pneumonia in children without pre-existing respiratory disease.
• Before admission:
  • General support, explanation and reassurance.
  • Respiratory support as required including oxygen.
  • Pulse oximetry to guide management is helpful.
  • Severe respiratory distress with falling level of consciousness and failure to maintain oxygenation indicates a need for intubation.
• In hospital:
  • Resuscitation and respiratory support as required.
  • Intravenous access and fluids in severe cases.
  • CXR confirmation of the diagnosis and identification of effusions and empyema.
• Drugs:
  • Antipyretics (avoid aspirin due to danger of Reye's syndrome).
  • Antibiotic treatment:
    • Antibiotic treatment of URTI does not prevent LRTI/pneumonia.⁹
    • However, it can be difficult to distinguish between viral and bacterial infection and young children can deteriorate rapidly, so consider antibiotic therapy depending on presentation, and likelihood of bacterial aetiology.
    • Choice of agent appears to be largely arbitrary (adult studies).^10,11
    • A penicillin, such as amoxicillin in a child-friendly formulation, should be used first line, unless there is reason to suspect a penicillin-insensitive organism (particularly pneumococcal disease). Recent research indicates that children with non-severe pneumonia on amoxicillin for 3 days do as well as those who receive it for 5 days.¹²
    • If child is genuinely allergic to penicillin, consider using a cephalosporin, macrolide or quinolone, depending on any local antibiotic prescription guidelines, patterns of resistance and suspected organism.
    • Vancomycin may be added to treatment of toxic looking children when there is a high rate of penicillin resistance.
    • Aciclovir is used for herpes virus pneumonia.

• Complete resolution after treatment should be expected in the vast majority of cases.
• Bacterial invasion of the lung tissue can cause pneumonic consolidation, septicaemia, empyema, lung abscess(esp. S. Aureus) and pleural effusion.
• Respiratory failure, hypoxia and death are rare unless previous lung disease or immunocompromised.

• Prevention is with pneumococcal vaccine and influenza vaccine for high risk individuals with pre-existing heart or lung disease.
• Smoking in the home is a major risk factor for all childhood respiratory infection.
• Zinc supplementation reduces the incidence of pneumonia by over 40% in malnourished children.¹³