Overview
Definition:
Bronchiolitis is a common viral lower respiratory tract infection in infants and young children, typically affecting the bronchioles and characterized by inflammation, edema, and increased mucus production, leading to airway obstruction.
Epidemiology:
It is the most common cause of hospitalization for infants in the first year of life, with a peak incidence between 3 to 6 months of age
Respiratory Syncytial Virus (RSV) is the most frequent pathogen, responsible for 70-80% of cases.
Clinical Significance:
Bronchiolitis is a significant cause of morbidity and healthcare resource utilization in pediatrics
Timely and appropriate management, including the judicious use of respiratory support like High-Flow Nasal Cannula (HFNC), is crucial for improving outcomes and preventing severe respiratory failure
Understanding HFNC initiation criteria is vital for DNB and NEET SS preparation.
Clinical Presentation
Symptoms:
Initially presents as an upper respiratory infection: rhinorrhea, cough, and low-grade fever
Progresses to lower respiratory symptoms: tachypnea, increased work of breathing (nasal flaring, grunting, retractions), wheezing, and crackles
Severe cases may show cyanosis, apnea, and lethargy.
Signs:
Physical examination reveals tachypnea, accessory muscle use, diffuse expiratory wheezing, and prolonged expiratory phase
Auscultation may reveal diffuse rhonchi or crackles
Hypoxia (SpO2 < 90% on room air) and increased respiratory rate are key indicators of severity
Paradoxical breathing patterns can indicate impending respiratory failure.
Diagnostic Criteria:
Diagnosis is primarily clinical, based on age, seasonal occurrence, characteristic symptoms, and physical findings
While viral testing (e.g., RSV antigen detection) can confirm the etiology, it does not typically alter management in uncomplicated cases
No specific laboratory or imaging criteria are required for diagnosis.
Diagnostic Approach
History Taking:
Focus on the onset and progression of symptoms, age of the infant, presence of fever, feeding tolerance, exposure to sick contacts (especially siblings), and any history of prematurity, congenital heart disease, or chronic lung disease
Red flags include apneic spells, significant feeding difficulties, lethargy, and worsening cyanosis.
Physical Examination:
A thorough cardiopulmonary examination is essential
Assess respiratory rate, effort (retractions, nasal flaring), breath sounds (wheezing, crackles), oxygen saturation, heart rate, and mental status
Assess hydration and feeding status.
Investigations:
Routine laboratory investigations are generally not indicated in mild to moderate cases
Chest X-ray may show hyperinflation, peribronchial thickening, and atelectasis but is often non-specific and not required for diagnosis or management unless pneumonia is suspected
Viral testing is usually reserved for epidemiological purposes or specific patient groups (e.g., immunocompromised).
Differential Diagnosis:
Conditions to consider include bacterial pneumonia, pneumonia due to other viruses, pertussis, foreign body aspiration, cystic fibrosis exacerbation, and congenital airway anomalies
The typical age group and epidemiological context of bronchiolitis aid in distinguishing it from these conditions.
Management
Initial Management:
Supportive care is the cornerstone
Maintain hydration (oral or IV if necessary)
Provide supplemental oxygen to maintain SpO2 > 90%
Nasal suctioning may help clear secretions
Avoid routine antibiotics as it is a viral infection
Bronchodilators and corticosteroids are generally not recommended for routine use in typical bronchiolitis.
Medical Management:
Primary medical management focuses on supportive measures: oxygen therapy, fluid management, and airway clearance
Hydration is critical
ensure adequate oral intake or consider nasogastric/intravenous fluids if oral feeding is compromised due to increased work of breathing or fatigue
Monitor fluid balance closely to prevent dehydration.
High Flow Nasal Cannula Initiation Criteria:
HFNC is indicated for infants with moderate to severe bronchiolitis who are tachypneic (e.g., RR > 50-60 breaths/min) and/or hypoxic (SpO2 < 90% despite standard oxygen) but are not in overt respiratory failure, and who are able to tolerate the interface
Key indicators include moderate to severe respiratory distress, persistent hypoxemia, and failure to improve with conventional oxygen therapy.
Supportive Care:
Close monitoring of respiratory status (rate, effort, oxygen saturation), fluid balance, and feeding is essential
Position the infant in a semi-upright position to ease breathing
Avoid over-sedation
Consider parental education on home care if discharged early
Apnea monitoring may be necessary for infants with a history of apnea or those at high risk.
Complications
Early Complications:
Apnea, particularly in premature infants or those with severe hypoxia, is a significant early complication
Dehydration due to poor oral intake and increased fluid losses is common
Secondary bacterial pneumonia can occur, though it is less common than viral etiology.
Late Complications:
Recurrent wheezing and increased risk of asthma development later in childhood have been associated with severe bronchiolitis
However, direct causality is complex
Prolonged respiratory compromise can lead to failure to thrive.
Prevention Strategies:
Preventive measures include hand hygiene, avoiding exposure to sick contacts, and preventing exposure to cigarette smoke
Palivizumab prophylaxis may be considered for high-risk infants (e.g., preterm infants < 29 weeks gestation, infants with hemodynamically significant congenital heart disease or chronic lung disease) during RSV season.
Prognosis
Factors Affecting Prognosis:
Prognosis is generally good for most infants, with recovery typically occurring within 7-14 days
Factors associated with poorer outcomes include prematurity, underlying chronic medical conditions (cardiac, pulmonary), severe hypoxia, apnea, and need for mechanical ventilation.
Outcomes:
Most infants recover fully with supportive care
Hospitalization rates vary, and a small percentage of infants require intensive care unit admission and mechanical ventilation
Long-term sequelae are debated but may include increased susceptibility to recurrent wheezing.
Follow Up:
Follow-up is primarily to ensure complete recovery and monitor for any residual respiratory symptoms
For infants with underlying risk factors, ongoing management of chronic conditions is crucial
Education regarding future respiratory illness prevention and management is important for parents.
Key Points
Exam Focus:
HFNC initiation criteria: Persistent hypoxemia (SpO2 < 90% despite supplemental O2), tachypnea (RR > 50-60), moderate-severe respiratory distress, and ability to tolerate interface
Bronchodilators and steroids are generally NOT indicated in typical bronchiolitis management
RSV is the most common cause.
Clinical Pearls:
Prioritize supportive care: oxygen, hydration, airway clearance
Monitor work of breathing closely
HFNC is a step-up therapy for those not improving with conventional oxygen
Differentiate from pneumonia and foreign body aspiration based on clinical context.
Common Mistakes:
Overuse of bronchodilators and steroids, leading to adverse effects and no proven benefit
Underestimating the severity and failing to initiate appropriate respiratory support (like HFNC) in a timely manner, leading to decompensation
Misdiagnosing bacterial pneumonia without clear evidence.