Bronchiolitis
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Introduction

This is the most common serious respiratory infection during infancy. It comes in winter epidemics, during which time, 2-3% of all infants are admitted to hospital each year. The primary cause is RSV – respiratory syncytial virus – which accounts for 80% of cases.
  • In more temperate climates, the epidemics come in the ‘wet’ season
  • Prognosis is good, but it does carry a mortality (~1%)

RSV

  • Highly Infectious
  • A single-stranded RNA virus
  • In adults, and older children, RSV only causes coryzal, and sometimes, flu-like symptoms.
  • Almost all children will have been infected at some stage by the age of 2
  • Often, infants catch the virus from older siblings, who bring it home from school, or they catch it directly themselves in environments with lots of children present.
  • Spread trough viral shedding, via coughing and sneezing. It can also live on surfaces and clothes outside the body for up to 5 hours.
  • Other causes include parainfluenza, virus, influenza virus and adenoviruses

Pathology

Typically infection spreads from the upper respiratory tract into the medium and small bronchi, resulting in epithelial necrosis. This results in oedema and epithelial shedding, which can cause obstruction, particularly on expiration.

 

Presentation

Typically aged <18 months
  • Annual incidence is about 11% of those <12months
  • Usually occurs between Nov and April, with peak in Jan and Feb
Coryzal symptoms come first 2-3 days, followed by:
  • Dry cough
  • Increasing breathlessness (often RR >50), may include Rib recession
  • Cough may continue for 1-2 weeks
  • Wheezing may/may not be present
  • Fever
  • Difficulty feeding – due to dyspnoea – is the main reason for admission
  • Symptoms often worse at night
  • Apnoea
  • Symptoms tend to be worse the younger the child. Children >” are rarely seriously ill, whilst those <^ months are at the greatest risk.

Signs and Symptoms of severe disease

  • Sharp, dry cough
  • Cyanosis
  • Pallor
  • Tachycardia
  • tachpnoea
  • Chest hyperinflation
    • Liver displaced downwards
    • Prominent sternum
  • Subcostal recession
  • Intercostal Recession
  • Prolonged expiration
  • End-respiratory crackles on auscultation
Intercostal recession in a neonate
An example of intercostal recession – in this example seen in a neonate. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Investigations

  • RSV – can be easily tested for with nasopharyngeal mucous secretions.
  • X-ray – usually shows hyperinflation
  • Blood gases – low O2, raised CO2.

 

Management

There is no specific treatment. The management is essentially supportive, and in many cases, will not require hospitalisation.

  • Signs that suggest severe disease: lethargy, cyanosis, co-existing illness (e.g. immunodefiency, congenital heart defects)
  • Oxygen – Delivered by nasal specs, head box, or in the smallest infants, tent. The amount of O2 is determined by pulse oximetry and blood gas results.
  • Steroids and antibiotics should not be given! (no evidence) – although they often are used
  • Bronchodilators via nebuliser are often used, but are not of proven benefit.
  • Mist is not of proven benefit and should not be administered
  • Fluids – can be given IV or by NG tube.
  • Mechanical ventilation – is needed in about 2% of cases.

Prognosis

Most cases recover within 2 weeks
Bronchiolitis obliterans is a rare complication. This is a form of non-reversible lung damage, in which the bronchioles become plugged by granulation tissue. There will be:
  • Very low FEV1 (<21% of normal)
  • Dry cough
  • SOB
  • Wheeze
  • There is very little treatment. Some cases may improve with a lung transplant.
  • There are many causes, not just RSV infection in childhood, often including occupational lung disease.

Prevention

There is an injection, containing monoclonal antibody; palivizumab. This is sometimes given to high risk (usually pre-term) babies. It reduces the severity of the infection and the risk of serious consequences. Its use is limited due to the cost, and the need for several injections

References

  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) currently works as a GP Registrar and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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