Bronchiolitis - Causes, Signs, Risk Factors, Diagnosis, and Intervention

Introduction

Bronchiolitis is a common lower respiratory tract infection. It is an acute inflammation of the bronchioles in the lungs caused by viruses. It causes mucus buildup in the bronchioles. It usually affects children, but it is also seen in adults. It causes blockage of the bronchioles in the lungs. As a result, it causes breathing problems and other symptoms.

What Is Bronchiolitis?

The trachea (windpipe) branches off into the right and left bronchi. The bronchus further divides into smaller branches. The smallest branches that lead to the air sacs in the lungs are called bronchioles. Bronchiolitis is the swelling of the bronchioles caused by viruses. It can be an acute or chronic infection. Acute bronchiolitis is a viral infection that usually affects children. Chronic bronchiolitis. Chronic bronchiolitis refers to airway diseases in adults like chronic obstructive pulmonary disease.

What Are the Causes of Bronchiolitis?

Viral bronchiolitis is commonly caused by the respiratory syncytial virus (RSV). Other viruses that cause bronchiolitis are human metapneumovirus, influenza, parainfluenza, coronavirus, adenovirus, rhinovirus, and mycoplasma bacteria. Bronchiolitis obliterans is a rare condition caused by a chronic lung infection or chronic exposure to toxins like formaldehyde, ammonia, or fumes from metal oxides. It can also occur as a complication of lung transplant or due to adverse reactions to medications. It is also called popcorn lung. It causes scarring in the bronchioles that leads to irreversible airway obstruction.

What Are the Effects of Bronchiolitis?

Bronchiolitis causes inflammation of the epithelial lining cells in the bronchioles. It results in necrosis of the epithelium. Goblet cells proliferate and produce excess mucus, but the epithelial regeneration with nonciliated impairs the elimination of secretions. Lymphocytic infiltration occurs and results in submucosal edema. This inflammation, edema, and debris obstruct the airway, resulting in hyperinflation, increased airway resistance, lung collapse, and ventilation-perfusion mismatch. However, recovery begins three to four days after regeneration of the bronchiolar epithelium and removal of mucus plugs by macrophages.

Bronchitis and bronchiolitis are inflammatory diseases caused by viruses. Both affect the airways. Bronchitis affects the bronchi (the main branch of the trachea), and bronchiolitis affects the bronchioles (smaller branches from the bronchi). Both conditions obstruct the airway.

What Are the Signs and Symptoms of Bronchiolitis?

The following signs are seen in children:

• Grunting noises.

• Difficulty in sucking and swallowing.

• Poor appetite.

• Indrawn chest wall.

• Cyanosis.

The initial symptoms of bronchiolitis are

• Fever.

• Cough.

• Runny nose.

• Loss of appetite.

The symptoms get worse after a few days and gradually become better. This includes

• Severe cough.

• Wheezing.

• Shortness of breath.

• Fatigue.

• Vomiting.

• Irritability.

Children with signs of respiratory distress progress to respiratory failure.

Bronchiolitis obliterans causes the following symptoms:

• Dry cough.

• Wheezing.

• Shortness of breath.

• Fatigue.

• Irritation of eyes, skin, nose, or mouth due to chemical exposure.

What Are the Complications of Bronchiolitis?

Severe bronchiolitis results in complications that include:

• Low oxygen levels.

• Cyanosis (bluish discoloration of the skin) due to lack of oxygen.

• Apnea (pauses in breathing).

• Dehydration.

• Respiratory failure.

What Are the Risk Factors?

Children with any of the following conditions are at high risk for disease progression. This includes

• Preterm infant (less than 37 weeks).

• Children less than three months of age.

• Immunodeficiency.

• Airway anomalies.

• Congenital heart disease.

• Chronic lung diseases.

• Neurological disorders.

• Exposure to tobacco smoke.

How Is Bronchiolitis Diagnosed?

The diagnosis of bronchiolitis is based on clinical examination. Other tests include

• Chest X-Ray - This is done to rule out the presence of pneumonia.

• Spirometry - It is a test done to measure the quality of breathing.

• Arterial Blood Gas Test - It measures the level of oxygen and carbon dioxide in the blood.

• Nasopharyngeal Swab - Nasal discharge or mucus is collected to identify the type of virus causing the infection.

How Is Bronchiolitis Managed?

Viral Bronchitis - Mild cases do not require treatment and resolve independently. Severe cases require hospitalization. Oxygen therapy may be required in some cases. Nebulized epinephrine, hypertonic saline, and nasal suctioning are recommended in some cases. Nasogastric or intravenous liquids are given to children who cannot maintain oral intake.

Bronchiolitis Obliterans - The treatment options include for bronchiolitis obliterans include the following:

• Corticosteroids - Corticosteroids are given to reduce inflammation, clear mucus secretions, and open the airways.

• Oxygen Therapy - Oxygen may be required in some cases.

• Immunosuppressant Medications - They are given to regulate the immune system.

• Lung Transplant - A lung transplant is required in severe cases.

• Breathing Exercises and Stress Reduction - This helps to ease breathing difficulties.

How to Prevent Bronchiolitis?

• It is a viral infection, and close contact with infected people should be avoided.

• Surfaces should be disinfected.

• Frequent hand washing prevents the spread of infection.

• Inhalation of smoke should be avoided.

• Passive immunization with Palivizumab against the respiratory syncytial virus is recommended during the first year of life for children with a gestational age of fewer than 29 weeks.

What to Expect With Bronchiolitis?

Children with mild viral bronchiolitis recover within two to three weeks. Rest, and increased fluid intake is required. Mild infections can be managed at home. There are no vaccines for the respiratory syncytial virus, but the annual flu shot is essential for everyone older than six months.

How to Manage Bronchiolitis at Home?

Mild symptoms can be managed at home, but severe symptoms require hospitalization.

• Humidification of Air - Cool-mist humidifiers or vaporizers can moisten the air, which helps to ease congestion and coughing.

• Upright Position - This helps to ease breathing.

• Liquid Intake - Increased fluid intake prevents dehydration.

• Intranasal Saline Drops - Saline drops help ease nasal congestion.

• Over-The-Counter Pain Relievers - Fever and pain medications can be given to children after consulting the doctor.

• Smoke-Free Environment - Smoke from tobacco or other chemicals can worsen the symptoms of bronchiolitis. It is essential to stay in a smoke-free environment to prevent complications.

Conclusion

Bronchiolitis is a common lower respiratory tract infection caused by viruses. Most of the cases improve with supportive care and do not require hospitalization. However, the infection is contagious as it spreads through air droplets. Therefore, it is important to maintain personal hygiene to prevent the spread of infection. In addition, early diagnosis and treatment play a vital role in preventing the risk of complications.