Model Answer
0 min readIntroduction
Acute lower respiratory infections (ALRI) are a leading cause of morbidity and mortality in children under five years of age globally, particularly in developing countries. The constellation of symptoms – rapid breathing, chest retractions, and decreased feeding following a prodrome of watery nasal discharge – strongly suggests an infectious etiology. While several possibilities exist, bronchiolitis, pneumonia, and croup are the most common considerations in this age group. This answer will focus on differentiating these conditions and outlining the initial management approach for this 10-month-old infant.
Differential Diagnosis
The clinical presentation points towards an acute lower respiratory infection. The key differential diagnoses include:
- Bronchiolitis: Typically caused by Respiratory Syncytial Virus (RSV), bronchiolitis is characterized by inflammation and obstruction of the small airways. It commonly affects infants under 2 years of age.
- Pneumonia: An infection of the lung parenchyma, pneumonia can be viral, bacterial, or fungal.
- Croup: Characterized by inflammation of the upper airway, primarily affecting the larynx and trachea.
Etiology and Clinical Features
Understanding the etiology helps differentiate between these conditions:
- Bronchiolitis: RSV is the most common cause (approximately 50-80% of cases). Other viruses include rhinovirus, adenovirus, and influenza. Symptoms include runny nose, cough, wheezing, rapid breathing, and chest retractions. Fever is usually low-grade.
- Pneumonia: Viral pneumonia is common in infants, with RSV, adenovirus, and parainfluenza virus being frequent culprits. Bacterial pneumonia is less common in this age group but can be caused by Streptococcus pneumoniae or Haemophilus influenzae. Symptoms include fever, cough, rapid breathing, chest retractions, and decreased feeding.
- Croup: Usually caused by parainfluenza virus. Characterized by a barking cough, stridor (a high-pitched whistling sound during inhalation), and hoarseness.
Diagnosis
Diagnosing the specific condition requires a thorough clinical assessment. The following are important diagnostic steps:
- History: Detailed history regarding the onset and progression of symptoms, feeding habits, and any underlying medical conditions.
- Physical Examination: Assess respiratory rate, heart rate, oxygen saturation, and auscultate the lungs for wheezing, crackles, or diminished breath sounds. Look for signs of respiratory distress like nasal flaring and intercostal retractions.
- Investigations:
- Pulse Oximetry: To assess oxygen saturation.
- Chest X-ray: To differentiate between bronchiolitis and pneumonia. Pneumonia typically shows infiltrates, while bronchiolitis often shows hyperinflation.
- Viral PCR: Nasopharyngeal swab for RSV, influenza, and other respiratory viruses can confirm the etiology.
- Complete Blood Count (CBC): May help differentiate between viral and bacterial infections (though not definitive).
Management
Initial management focuses on supportive care:
- Oxygen Therapy: Maintain oxygen saturation above 90%.
- Hydration: Encourage oral fluids. If the infant is unable to feed adequately, consider intravenous fluids.
- Suctioning: Clear nasal passages of secretions.
- Antipyretics: For fever, use paracetamol or ibuprofen.
- Bronchodilators: While often used, the evidence for benefit in bronchiolitis is limited. A trial of nebulized salbutamol may be considered.
- Hospitalization: Consider hospitalization if the infant has significant respiratory distress, oxygen saturation <90%, inability to feed, or underlying medical conditions.
Specific Considerations
Given the age of the infant (10 months) and the presentation, bronchiolitis is the most likely diagnosis. However, pneumonia cannot be ruled out without a chest X-ray. Croup is less likely given the absence of a barking cough and stridor.
Conclusion
In conclusion, the 10-month-old infant presenting with watery nasal discharge, rapid breathing, chest retractions, and decreased feeding likely has bronchiolitis, though pneumonia remains a possibility. Initial management should focus on supportive care, including oxygen therapy, hydration, and close monitoring. A chest X-ray is crucial to rule out pneumonia and guide further management. Early recognition and appropriate intervention are essential to prevent complications and ensure a favorable outcome.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.