The nurse measured his oxygen saturations at 90% on air and started the child on oxygen therapy before calling the Paediatricians. After a quick history and assessment of the baby the Paediatricians told the parents that their child had bronchiolitis and was going to be admitted. He would need help with his breathing and feeding for a while but that he should make a good recovery and with a bit of luck would be home within a few days.
So what is bronchiolitis?
Bronchiolitis is an acute viral infection affecting the small airways of the lungs in young children typically from two to six months old but it can occur up to 2 years old. It particularly occurs over the winter period and is the most common reason for children to be admitted to hospital.
What viruses cause bronchiolitis?
By far and away the most common virus in bronchiolitis is Respiratory Syncytial Virus (RSV) which causes about 70% of infections. Other causes include Rhinovirus, Parainfluenza Virus, Human Metapneumovirus, Influenza Virus and Adenovirus.
How does bronchiolitis present?
The most common features of bronchiolitis include:
- Fever – usually <38.5oC
- Cough – which sounds “wet” (listen to the typical cough)
- Respiratory distress – tachypnoea, intercostal and subcostal recession, wheeze, crackles, nasal flaring, grunting, cyanosis
- Coryza – blocked or runny nose
Clinical signs that indicate urgent referral to hospital include:
- Severe respiratory distress – grunting, marked chest recession, respiratory rate >70 breaths per minute
- Oxygen saturations <92% in air
The coryzal symptoms are a particular problem for babies as they are obligate nose breathers. In normal life this helps them breathe whilst either breast or bottle feeding; but when their nose is blocked they cannot breathe and feed at the same time and so they don’t feed. This can rapidly lead to dehydration.
Some children are particularly at risk of having severe bronchiolitis as they either have an underlying immunodeficiency or they have a condition which means that their body will not cope well with the hypoxia and raised pulmonary blood pressure associated with bronchiolitis.
Risk factors for severe disease include:
- Chronic lung disease
- Haemodynamically significant congenital heart disease
- Prematurity (<32 weeks)
- Neuromuscular disorders
- <3 months old
It is not normally necessary to test children with bronchiolitis for viruses. Once RSV is known to be circulating in the population during the winter time then bronchiolitis can be diagnosed based on the clinical features.
If a viral specimen is being sent to the lab then a nasopharyngeal aspirate is the specimen of choice. This involves washing cells out of the back of the nose with normal saline and either doing antigen tests or PCR. This is not a pleasant procedure to have done… remember what it’s like to accidentally inhale underwater in a swimming pool?! However, before bronchiolitis season gets underway it is often necessary to make a diagnosis and an NPA is the best way.
How is bronchiolitis treated?
The treatment of bronchiolitis is supportive paying particular attention to respiratory support and hydration.
Children with oxygen saturations <92% in air should be given oxygen. It is uncommon but occasionally children with bronchiolitis need more invasive respiratory support such as continuous positive airway pressure (CPAP) or even mechanical ventilation. Suctioning of upper airway secretions should be done if they are causing significant obstruction and causing apnoea or feeding problems.
Hydration in bronchiolitis is normally maintained by oral or nasogastric feeding but occasionally IV fluids are indicated in the most severe cases.
Antibiotics, bronchodilators and steroids are not normally indicated.
Bronchiolitis is normally a self-limiting infection with the average length of stay in hospital being 2 days; however the cough and wheeze can persist for up to 3-4 weeks. The mortality in developed countries is less than 1 in 1000 cases.
Most children can be discharged once they are stable with adequate oral hydration and when they can keep their oxygen saturations >92% in air over 4 hours (including when they are asleep!).
The most serious complications of bronchiolitis are:
- Dehydration due to fever and decreased oral intake
- Respiratory failure – including apnoea (stopping breathing) and hypoxia (low oxygen)
So the baby was admitted to the paediatric ward where he continued on oxygen and required nasogastric feeding for a few days. Within a week the parents were taking him home and whilst he was still not quite back to normal everyone was confident he would eventually make a full recovery.