What is bronchiolitis ?

Bronchiolitis is a lung disease of the young that causes mild to moderate respiratory distress due to aa viral infection affecting the lower respiratory tract. 

Respiratory Syncytial Virus (RSV) causes a minor self-limiting infection that results in respiratory failure and accounts for 85% of bronchiolitis in neonates, affecting about 1% of hospitalised newborns.⁵

Oxygen and water provide supportive care for bronchiolitis. The infection is not treated by any specific drugs.¹

Signs and Symptoms

• Blocked nose
• Low-grade fever
• Cough
• Fast or noisy breathing (wheezing)
• Trouble eatingIrritability 

are all possible signs of bronchiolitis.

Cause

Bronchiolitis can have multiple causes, including the respiratory syncytial virus. Although the virus can affect people of any age, newborns typically have the most severe symptoms.

History of bronchiolitis 

Engle and Newns were the first to use the term ‘bronchiolitis’ in 1940. They described this severe, and fatal, lower respiratory tract disease affecting young children.⁴

According to the 1941 description, bronchiolitis is an inflammatory respiratory obstruction caused by mucus in the bronchioles that manifests with a temperature, pharyngeal cough, and some gastrointestinal upset, and then goes through a phase in which ‘obstructive dyspnea dominates the clinical picture and the bronchioles become plugged with exudate.²

The respiratory syncytial virus is the most frequent virus linked to bronchiolitis. However, as time passed, additional viruses were discovered that caused the infection; these viruses include the following:

• Rhinovirus in humans
• Coronavirus
• Metapneumovirus in humans
• Adenovirus
• Parainfluenza virus
• Bocavirus in humans

Diagnosis 

Most often, the history of the illness and physical examination helps to diagnose bronchiolitis. Common indications are runny nose, fever, stuffy nose, appetite loss, and cough.¹⁰ 

The cough intensifies to cause wheezing, shortness of breath, and worsening symptoms.¹¹ This confirms bronchiolitis. To rule out other diseases further investigations like blood tests, virus tests, and chest X-rays may be needed.¹⁰

Long-term Effects 

Long-term consequences of bronchiolitis include 

• Asthma
• Recurrent wheezing
• Reduced lung function 

Hospitalized infants and children with bronchiolitis are more likely to experience these problems than non hospitalized infants³

Most children and young adults with bronchiolitis recover well. In rare cases, newborns with the infection may have respiratory failure. 

Adults who catch RSV infection, which can cause bronchiolitis, may experience problems including pneumonia, a worsening of symptoms related to chronic obstructive pulmonary disease (COPD), asthma flare-ups, and bronchiolitis itself. Adults with weakened immune systems or underlying cardiac disorders are more vulnerable to severe bronchiolitis and its associated complications, which include infection and worsening of heart symptoms.⁹

1. Chronic bronchiolitis - Young children and adults will not feel better for months and not put on enough weight. Hyperinflation(larger lungs than normal due to trapped air, occurring because air can’t be exhaled) and airway blockage are shown in lung function tests with normal static compliance. The majority of infants and children recover and stop needing oxygen, and the short and medium-term prognosis is unexpectedly good
2. Cough and Wheezing - According to research, in the two years following an acute bronchiolitis episode, chronic lower respiratory tract symptoms are exceedingly common. Of the afflicted newborns, 75% will experience more wheezing, 60% will have three or more episodes, and 33% will experience respiratory symptoms, primarily coughing, for a minimum of one hundred days. 10 to 15% of patients will require hospital readmission for a different acute respiratory condition. Children who have a family history of atopy (when the immune system causes allergic diseases to develop) are more likely to experience recurrent wheezing and have increased airway resistance⁵
3. Abnormal airway lability - Although measuring airway reactivity in newborns and young children can be challenging, the high incidence of wheezing implies that bronchial hyperreactivity is a prevalent aftereffect of acute bronchiolitis^2,5
4. Bronchiolitis and atopy- Research suggests a connection between atopy⁷ and bronchiolitis. There is an increased risk of wheezing or asthma in the future. Asthma development has been connected to both the degree of atopy and bronchiolitis, suggesting a possible connection between these illnesses⁷
5. Abnormalities in small airway functions - Two years after being diagnosed with RSV bronchiolitis in infancy, almost 50% of infants still exhibit significant lung hyperinflation, a sign of ongoing small airway blockage.⁵ Seventy-five percent of them still had mild abnormalities related to small airway function. It is yet unknown if they and others who resemble them will eventually acquire chronic obstructive lung disease⁵

Potential genetic causes of acute viral bronchiolitis's long-term repercussions include atopy and bronchial reactivity⁵

Previous lung injury: respiratory issues in newborns early viral infection ⁵

Unfavourable environmental conditions: pollution and passive smoking exposure to further infections overcrowding and siblings⁵

Reduced suppressor T cells indicate an aberrant immunological response⁵

Management of long-term consequences of bronchiolitis 

1. Monitoring, evaluating and follow-up: To monitor for any unfavourable long-term pulmonary outcome, such as asthma attacks, recurring wheeze attacks, and compromised lung function, children who have experienced severe bronchiolitis especially those who require mechanical ventilation should have a systemic pulmonary follow-up. It is critical to regularly monitor and evaluate respiratory health, including spirometry testing, in order to identify and treat any long-term impacts as soon as possible³
2. Drug-related interventions: Bronchodilators and other drugs only offer slight short-term improvements. There is insufficient evidence to support their routine usage in treating bronchiolitis⁶. However, since bronchodilator medication may help control any asthma-like symptoms that may arise, it may be reasonable to try it with older children who have a personal or family history of asthma⁶. In bronchiolitis, antibiotics are for high-risk cases if a subsequent bacterial infection is suspected. In certain high-risk populations, antiviral medication such as ribavirin may be recommended; nevertheless, its overall therapeutic effectiveness is still debatable⁶
3. Non-pharmacological interventions: Saline nose drops applied before feedings can help hospitalized infants with bronchiolitis control nasal congestion.² When treating the symptoms of acute bronchiolitis, nasal decongestants may be just as helpful as inhaled epinephrine. Heliox, a helium and oxygen mixture, may alleviate respiratory distress in certain bronchiolitis cases^4,6
4. Resolving inherent factors: Longer periods of mechanical ventilation and a family history of atopic disease may be linked to an increased risk of unfavourable long-term pulmonary outcomes.³ When feasible, addressing these underlying causes may help lessen bronchiolitis's long-term impacts

Summary

• The precise processes and long-term trajectories of bronchiolitis are still under investigationThe long-term effects of mechanical ventilation, include an increased risk of recurrent wheezing, asthma, and reduced lung function severe bronchiolitis in children increases the chance of recurrent wheezing and asthma later in life, especially in those who need mechanical ventilation. Nonetheless, after 5–10 years of follow-up, the difference in recurrent wheeze between the bronchiolitis and control groups tends to become insignificant⁸
• Long-term lung function impairment, such as obstructive patterns, may occur in children with a history of severe bronchiolitis, especially in those who require mechanical ventilation therefore it is very important to monitor and evaluate
• The exact level of Bronchiolitis and Atopy link and the consequences of the development of asthma and other respiratory disorders may vary depending on different studies and circumstances. Despite evidence suggesting an association between bronchiolitis and atopy further research is needed
• Bronchiolitis's long-term repercussions entail vigilant observation, prudent medication, and treatment of any underlying risk factors. For long-term results, a multidisciplinary strategy involving respiratory specialists is essential