Bronchiolitis, most commonly due to respiratory syncytial virus (RSV), affects everyone by the age of 2yrs.
Bronchiolitis, most commonly due to respiratory syncytial virus (RSV), affects everyone by the age of 2yrs. Whether you meet this infection in your first winter, or your second, determines how ill you will be. RSV invades the nasopharyngeal epithelium and spreads to the lower airways where it causes increased mucus production, desquamation, and then bronchiolar obstruction. The net effect is pulmonary hyperinflation and atelectasis. The other causes of bronchiolitis include infection with parainfluenza, influenza, adenovirus, rhinovirus, metapneumovirus, chlamydia, and Mycoplasma pneumoniae.
There is an increased risk of severe infection in infants with CHD, CLD of prematurity, immunodeficiency, and other lung disease.
In winter months infants with a typical history will have had coryza, followed by a dry cough, followed by worsening breathlessness. Other features in the history include:
- feeding difficulty;
- episodes of apnoea.
Rarely, other presenting histories in babies include:
- encephalopathy with seizures due to hyponatraemia;
- apnoea and near miss sudden infant death.
Examination and investigation
A thorough examination is needed in order to assess the degree of respiratory distress:
- cyanosis or pallor;
- dry cough;
- subcostal and intercostal recession;
- chest hyperinflation;
- prolonged expiration;
- pauses in breathing or apnoea;
- wheeze and crackles.
Key investigations include:
- Pulse oximetry: to assess oxygenation.
- CXR: to assess hyperinflation, atelectasis, and consolidation.
- Nasopharyngeal swab: immunofluorescent antibody testing for RSVbinding.
The treatment of RSV bronchiolitis is mainly supportive and includes:
- Oxygen to achieve pulse oximetry saturation >92%.
- If tachypnoea, limit oral feeds and use a NGT.
- Bronchodilators for wheeze: nebulized salbutamol, ipratropium, andadrenaline have all been used in studies. The best evidence is for nebulized adrenaline.
- Mechanical ventilation for severe respiratory distress or apnoea.
Antiviral therapy with ribavirin should be reserved for immunodeficient patients and those with underlying heart or lung disease, although its benefit is uncertain.
Palivizumab is a monoclonal antibody to RSV and can be used as prophylaxis. Preterm babies and oxygen-dependent infants at risk of RSV infection can receive a monthly IM injection (for 5mths starting in October) to reduce risk of hospitalization and the need for mechanical ventilation.
Recurrent cough, wheeze, and tachypnoea may occur after RSV infection. These may require treatment and are best assessed in outpatients. Daily oral montelukast granules can sometimes help reduce the symptoms. A proportion of patients may develop asthma they may have been predisposed to develop this problem irrespective of RSV in early infancy.