Respiratory
You are asked to assess a 4 month old boy brought to the Emergency Department by his parents. They describe several days of nasal congestion and cough. You note tachypnoea and bilateral wheeze on auscultation. You suspect bronchiolitis, how is the diagnosis confirmed?
Answer:
- Acute bronchiolitis is a clinical diagnosis.
- Do not routinely perform blood tests in the assessment of a child with bronchiolitis.
- Chest x-ray
- Do not routinely perform a chest X-ray in children with bronchiolitis, because changes on X-ray may mimic pneumonia and should not be used to determine the need for antibiotics.
- Consider performing a chest X-ray if intensive care is being proposed for a child.
Bronchiolitis
Respiratory
Last Updated: 10th February 2023
Bronchiolitis is a condition which predominantly affects infants of less than 12 months of age, with a peak incidence between the ages of three and six months. Approximately 1 in every 3 infants will develop clinical bronchiolitis in the first year of life and 2–3% of these infants will require hospitalisation. Bronchiolitis most commonly occurs in the UK from October to March, with most infections occurring in an epidemic lasting around six weeks, the exact timing of which varies from year to year.
Pathophysiology
Bronchiolitis is caused by a viral infection, most commonly respiratory syncytial virus, of the epithelial lining of the lower bronchial tree. Infected epithelial cells slough off into the small airways and the alveolar spaces. This, together with mucus, causes variable obstruction of the small airways, with complete obstruction and collapse in some, and partial obstruction in others. These changes result in impaired gas exchange leading to hypoxia and breathlessness.
Prognosis
For most infants the disease is self-limiting, typically lasting for 3–7 days.
Bronchiolitis is likely to be more severe in infants:
- With chronic lung disease (including bronchopulmonary dysplasia), haemodynamically significant congenital heart disease, neuromuscular disorders, or immunodeficiency.
- Under three months of age.
- Born prematurely (particularly before 32 gestational weeks).
Bronchiolitis is associated with an increased risk of chronic respiratory conditions, including asthma, however, it is unclear whether it causes these conditions.
Clinical features
Consider a diagnosis of bronchiolitis in infants who have experienced a coryzal prodrome lasting 1–3 days, followed by:
- Persistent cough AND
- Either tachypnoea or chest recession (or both) AND
- Either wheeze or crackles on chest auscultation (or both).
Other common symptoms include:
- Fever (in around 30% of cases, usually of less than 39°C).
- Poor feeding (typically after 3 to 5 days of illness).
- Apnoea without other clinical signs in young infants (in particularly those under 6 weeks of age).
Symptoms usually peak between 3 and 5 days and the cough resolves in 90% of infants within 3 weeks.
Consider a diagnosis of pneumonia if the child has high fever (over 39°C) and/or persistently focal crackles.
Assessment
Measure oxygen saturation using pulse oximetry in every child presenting to secondary care with clinical evidence of bronchiolitis.
Admit children with bronchiolitis to hospital if they have any of the following:
- Apnoea (observed or reported)
- Persistent oxygen saturation of less than 92% on air
- Inadequate oral fluid intake (50 - 75% of usual volume) or no wet nappy for 12 hours
- Persisting severe respiratory distress, for example grunting, marked chest recession or a respiratory rate of over 70 breaths/minute
Suspect impending respiratory failure (and respond appropriately) if any of the following are present:
- Signs of exhaustion, for example listlessness or decreased respiratory effort
- Recurrent apnoea
- Failure to maintain adequate oxygen saturation despite oxygen supplementation
Investigations
- Acute bronchiolitis is a clinical diagnosis.
- Do not routinely perform blood tests in the assessment of a child with bronchiolitis.
- Chest x-ray
- Do not routinely perform a chest X-ray in children with bronchiolitis, because changes on X-ray may mimic pneumonia and should not be used to determine the need for antibiotics.
- Consider performing a chest X-ray if intensive care is being proposed for a child.
- ABG
- Do not routinely carry out blood gas testing in children with bronchiolitis.
- Consider carrying out capillary blood gas testing in children with severe worsening respiratory distress (when supplemental oxygen concentration is greater than 50%) or suspected impending respiratory failure.
Management
- Do not use any of the following to treat bronchiolitis in children: antibiotics, hypertonic saline, nebulised adrenaline, salbutamol, montelukast, ipratropium bromide, systemic or inhaled corticosteroids.
- Give oxygen supplementation to children with bronchiolitis if their oxygen saturation is persistently less than 92%.
- Consider continuous positive airway pressure (CPAP) in children with bronchiolitis who have impending respiratory failure.
- Do not routinely perform upper airway suctioning in children with bronchiolitis. Consider upper airway suctioning in children who have respiratory distress or feeding difficulties because of upper airway secretions. Perform upper airway suctioning in children with bronchiolitis presenting with apnoea even if there are no obvious upper airway secretions.
- Give fluids by nasogastric or orogastric tube in children with bronchiolitis if they cannot take enough fluid by mouth.
- Give intravenous isotonic fluids to children who do not tolerate nasogastric or orogastric fluids or have impending respiratory failure.
Discharge
Consider discharge when the child:
- is clinically stable.
- is taking oral fluids.
- has maintained oxygen saturation over 92% in air for 4 hours, including a period of sleep.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
