Bronchiolitis: Causes, Symptoms & Treatment

What is Bronchiolitis?

Bronchiolitis is a viral respiratory infection that causes the small airways in the lungs, called bronchioles, to become inflamed and congested. This inflammation leads to swelling and mucus buildup, making it harder for air to move in and out of the lungs. As a result, infants and young children with bronchiolitis may experience difficulty breathing, wheezing, coughing, and other respiratory symptoms.

Bronchiolitis is most common in infants and young children under 2 years of age, with peak severity usually between 2 and 6 months of age. It most often occurs in the fall and winter months during the respiratory virus season. While most cases of bronchiolitis are mild and can be managed at home, some infants may develop severe symptoms that require hospitalisation for supportive care and monitoring.

Causes of Bronchiolitis

• Respiratory Syncytial Virus (RSV): RSV is the most frequent cause of bronchiolitis, responsible for the majority of cases in infants. It spreads through respiratory droplets and direct contact with contaminated surfaces.
• Adenovirus: This virus can also infect the bronchioles and trigger bronchiolitis symptoms.
• Influenza Virus: This flu virus can lead to bronchiolitis, particularly in young children.
• Parainfluenza Virus: A common cause of respiratory infections in children, sometimes resulting in bronchiolitis.

Respiratory Syncytial Virus (RSV)

RSV is the leading cause of bronchiolitis and spreads through respiratory droplets when an infected person coughs or sneezes or by touching contaminated surfaces and then touching the eyes, nose, or mouth.

While RSV may cause only mild cold-like symptoms in older children and adults, it can lead to more severe lower respiratory tract involvement in infants, resulting in bronchiolitis or pneumonia. Premature infants, babies with underlying health conditions, and those exposed to secondhand smoke are at higher risk for severe RSV infections.

Other Viruses

• Adenovirus
• Influenza virus
• Parainfluenza virus
• Human metapneumovirus
• Rhinovirus
• Bocavirus
• Coronavirus

Risk Factors for Bronchiolitis

• Age under 3 months
• Premature birth (born before 37 weeks gestation)
• Exposure to secondhand smoke or air pollution
• Living in crowded conditions, such as daycare centers or households with many occupants
• Not being breastfed, as breast milk contains protective antibodies
• Underlying health issues, such as congenital heart disease, chronic lung disease, or a weakened immune system

Symptoms of Bronchiolitis

• Runny nose and congestion
• Persistent cough that worsens over time
• Low-grade fever
• Wheezing or a high-pitched whistling sound when breathing
• Rapid, shallow, or labored breathing (tachypnea)
• Retractions (visible pulling in of the chest muscles during breathing)
• Nasal flaring
• Difficulty feeding or decreased appetite
• Irritability or fussiness
• Apnoea (brief pauses in breathing), especially in young infants
• Bluish discolouration of the lips or fingernails (cyanosis) in severe cases

Complications of Bronchiolitis

• Dehydration due to difficulty feeding and increased breathing effort
• Respiratory failure requiring mechanical ventilation (in severe cases)
• Hospitalisation, particularly for infants with underlying health conditions or severe symptoms
• Secondary bacterial infections, such as pneumonia
• Prolonged cough that may persist for several weeks after the acute illness
• Recurrent wheezing episodes or an increased risk of asthma later in childhood

How Bronchiolitis is Diagnosed

1. Medical History and Physical Examination: The doctor will ask about the onset and progression of symptoms, feeding patterns, and breathing difficulties. They will also assess risk factors and signs of respiratory distress during a physical exam.
2. Listening to the Lungs: Using a stethoscope, the doctor will listen for wheezing, crackles, or other abnormal lung sounds that indicate airway obstruction.
3. Pulse Oximetry: A small sensor placed on the child's finger or toe measures the oxygen saturation in the blood, helping determine if supplemental oxygen is needed.
4. Imaging and Laboratory Tests (if necessary):
   • Chest X-ray to rule out other causes or complications, such as pneumonia
   • Blood tests to assess the severity of the infection or check for dehydration
   • Viral testing, such as a nasal swab, to identify the specific virus (e.g., RSV) causing the infection

Medical History and Physical Examination

During the initial assessment, the doctor will gather information about your child's symptoms, their onset and duration, and any underlying health conditions. They will enquire about feeding patterns, breathing difficulties, and exposure to sick contacts or environmental risk factors.

The physical examination will focus on assessing your child's general appearance, breathing patterns, and signs of respiratory distress, such as nasal flaring, chest retractions, or rapid breathing.

Listening to the Lungs

Using a stethoscope, the doctor will listen for wheezing, crackles, or decreased breath sounds, which are characteristic findings in bronchiolitis. Wheezing is a high-pitched, whistling sound that occurs when air passes through narrowed airways, while crackles are small clicking or bubbling sounds that indicate the presence of fluid in the lungs.

Oxygen Saturation and Pulse Oximetry

Pulse oximetry is a non-invasive method of measuring the oxygen saturation in the child's blood. A small sensor is placed on the finger or toe, and the device displays the percentage of oxygen-saturated haemoglobin. This test helps determine if the child requires supplemental oxygen therapy and can guide decisions regarding hospitalisation.

Imaging and Laboratory Tests (if needed)

• Chest X-ray: This imaging test may be performed if the child has severe symptoms or if the bronchiolitis diagnosis is uncertain, helping to exclude complications such as pneumonia.
• Blood tests: These tests can help assess the severity of the infection, check for signs of dehydration, or identify any underlying health issues.
• Viral testing: A nasal swab may be collected to identify the specific virus causing the infection, such as RSV. This test is typically performed in hospital settings or when the child has severe symptoms.

Treatment of Bronchiolitis

• Supportive care: Ensuring the child remains comfortable and well-hydrated is the mainstay of bronchiolitis treatment.
• Oxygen therapy: Supplemental oxygen may be provided if the child's blood oxygen levels are low.
• Intravenous fluids: If the child is unable to feed adequately due to breathing difficulties, IV fluids may be necessary to prevent dehydration.
• Close monitoring: Doctors will closely observe the child for any signs of worsening bronchiolitis symptoms or complications.

Home Care

• Encourage frequent intake of fluids to maintain hydration.
• Use saline drops and gentle suctioning to clear nasal congestion and make breathing easier.
• Run a cool-mist humidifier to add moisture to the air and ease breathing.
• Monitor your child's symptoms and seek medical attention if they worsen or you notice signs of respiratory distress.

Medications

• Fever reducers, such as acetaminophen or ibuprofen, may be given to help manage fever and discomfort.
• Bronchodilators (e.g., salbutamol) and corticosteroids are not routinely recommended for bronchiolitis, but a monitored, single therapeutic trial of a bronchodilator may be considered in some older infants with an asthma-like history or significant wheeze — continued use should depend on clinical response.
• Antibiotics are not indicated unless there is clinical or laboratory evidence of a secondary bacterial infection.
• Decisions about medications should be individualised and guided by a paediatrician.

Hospital Care

• Oxygen therapy, if blood oxygen levels are persistently low.
• Intravenous fluids, if the child is unable to feed or showing signs of dehydration.
• Close monitoring of breathing, oxygen levels, and vital signs to watch for any complications.
• In rare cases, respiratory support such as CPAP (continuous positive airway pressure) or mechanical ventilation, if the child is in respiratory failure.

Prevention of Bronchiolitis

• Practise frequent handwashing, especially before handling your baby.
• Avoid exposure to sick individuals, particularly during the peak RSV season.
• Clean and disinfect toys, surfaces, and other objects that may harbour viruses.
• Do not expose your infant to cigarette smoke or other air pollutants.
• Breastfeed your baby, as breast milk provides protective antibodies.
• Limit your infant's contact with crowded places, especially during the winter months when respiratory viruses are more prevalent.
• For high-risk infants, such as those born prematurely or with underlying health conditions, preventive medication (palivizumab) may be recommended to help protect against severe RSV infection.

Living with Bronchiolitis

Caring for a child with bronchiolitis can be challenging, but most cases are mild and improve with supportive care at home. It's important to monitor your child's symptoms closely and seek medical attention if they worsen or you notice signs of respiratory distress. While the cough and congestion may linger for a few weeks after the acute illness, long-term complications are rare in healthy infants. However, some children who had severe bronchiolitis may be more likely to develop recurrent wheezing or asthma later in childhood, especially if they have a family history of these conditions.

When to See a Doctor

• Difficulty breathing, with rapid, shallow, or laboured breaths
• Bluish discolouration of the lips or fingernails
• Persistent fever above 38°C
• Dehydration, with fewer wet diapers, dry mouth, or sunken eyes
• Lethargy or extreme irritability
• Apnoea (pauses in breathing) or choking
• Worsening cough or wheezing

Conclusion

Bronchiolitis is a common viral respiratory infection that can cause significant distress for infants and young children. By understanding bronchiolitis causes, risk factors, and symptoms, parents and caregivers can take steps to prevent infection and seek timely medical care when necessary. Supportive care, including maintaining hydration, managing fever, and ensuring adequate oxygenation, is the mainstay of bronchiolitis treatment. In severe cases, hospitalisation may be required for close monitoring and advanced respiratory support.

At Metropolis Healthcare, we understand the importance of accurate and timely diagnosis in managing childhood illnesses like bronchiolitis. Our state-of-the-art diagnostic laboratories offer a comprehensive range of tests to help identify the cause of your child's respiratory symptoms and guide appropriate treatment. With a network of over 750 towns in India, supported by a robust network of more than 220 laboratories, 4600 plus service centres, and over 10,000 touchpoints across India, we are committed to providing reliable, patient-centric care to support your child's health and well-being.

FAQs

Is bronchiolitis contagious?

Yes, bronchiolitis is highly contagious, as it is caused by respiratory viruses that spread easily through close contact, coughing, sneezing, or touching contaminated surfaces. The viruses can remain infectious on surfaces for several hours, making it important to practice good hand hygiene and disinfect toys and other objects regularly.

Can bronchiolitis be prevented?

While it's not always possible to prevent bronchiolitis, there are steps you can take to reduce your child's risk of infection. These include frequent handwashing, avoiding exposure to sick individuals, cleaning and disinfecting surfaces, avoiding cigarette smoke, and breastfeeding your baby to provide protective antibodies. For high-risk infants, preventive medication may be recommended.

How long does bronchiolitis last?

The duration of bronchiolitis can vary depending on the severity of the infection and the child's overall health. Typically, the illness lasts about 7-10 days, but some children may experience bronchiolitis symptoms for up to 2-3 weeks. The cough associated with bronchiolitis can linger for several weeks, even after other symptoms have resolved.

Can adults get bronchiolitis?

Bronchiolitis in the classic paediatric sense refers to viral infection of the small airways in infants and young children and is uncommon in healthy adults. Adults with lower-airway small-airway inflammation may present with different clinical entities — for example, acute bronchiolitis in older adults is rare and usually occurs in the context of severe viral infection or immunocompromise; bronchiolitis obliterans is a distinct, often chronic condition linked to inhalational injury, autoimmune disease, or post-transplant complications. Adult presentations differ from paediatric bronchiolitis in cause, course, and management, so adult patients should be assessed by clinicians for the specific diagnosis.

What is the difference between bronchiolitis and pneumonia?

Bronchiolitis primarily affects the small airways (bronchioles) and is almost always caused by a viral infection, while pneumonia is an infection of the lung tissue itself and can be caused by viruses, bacteria, or fungi. Pneumonia tends to cause more severe symptoms, such as high fever, chills, and chest pain, and may require antibiotic treatment if caused by bacteria. In some cases, bronchiolitis can lead to pneumonia as a complication, especially in infants with weakened immune systems or underlying health conditions.

References

1. https://www.ncbi.nlm.nih.gov/books/NBK519506/
2. https://www.lung.org/lung-health-diseases/lung-disease-lookup/bronchiolitis/learn-about-bronchiolitis
3. https://my.clevelandclinic.org/health/diseases/8272-bronchiolitis
4. https://www.nhs.uk/conditions/bronchiolitis/
5. https://medlineplus.gov/ency/article/000975.htm