BRONCHIOLITIS
INTRODUCTION:
- Acute infectious inflammatory disease of the URT and LRT that result in obstruction of the small airways.
- Occur in all age gp, larger airways of older children and adults better accommodate mucosal edema, severe respiratory symptoms limited to young infants.
- 90% are aged 1-9 months (rare after 1 year of age), boys affected more than girls.
- Major concern not only the acute effects bronchiolitis but the possible development of chronic airway hyperreactivity (asthma).
- Infants affected most often because of their small airways, high closing volumes, and insufficient collateral ventilation.
ETIOLOGICAL AGENTS:
- Respiratory Syncytial Virus (RSV):
- 75% of children
- Human metapneumovirus, parainfleunze, influenza, rhinovirus, adenovirus
- Mycoplasma pneumoniae:
- 5-15% particularly among older children and adults
RISK FACTORS:
- Low birth weight (PREM)
- Lower socioeconomic gp
- Parental smoking
- Crowded condition, daycare
- Chronic lung diseasebronchopulmonary dysplasia
- CHD + pulmonary hypertension
- Aiways anomalies
- Congenital/ acquired immunedeficiency disease
PATHOPHYSIOLOGY:
Acquisition of infection
↓
Necrosis of respiratory epithelium (<24h)
↓
Proliferation of goblet cells > excessive mucus production
↓
Nonciliated epithelium cell regeneration > impaired secretion elimination (removed by macrophages)
↓
Lymphocytic infiltration > submucosal edema
↓
Cytokine and chemokines released > Increased cellular recruitment
↓
Obstruction due to inflammatory cells debris + fibrin + mucus + edema fluid (not due to bronchoconstriction)
↓
Bronchioles obstruction lead to hyperinflation + increase airways resistance + atelactasis + V/Q mismatch
↓
Recovery with bronchiolar epithelium regeneration after 3-4 days
CLINICAL PRESENTATION:
- Coryza – rhinorrhea, fever
- Progressive breathlessness
- Feeding difficulty
- Hypothermic
- Respiratory distress, nasal flare, irritability
- Sharp and dry cough
- Intercostal and subcostal retractions
- Extensive rhonchi
- Tachypnoea and tachycardia
- Recession
- Hyperinflated chest – sternum prominent + liver displaced
- Fine end inspiratory crackles
- High pitched wheezes :expiratory > inspiratory
- Cyanosis / pallor
INVESTIGATION:
- FBC:Lymphocytosis
Nasopharyngeal swab/ nasal wash:
- To detect RSA antigen in epithelial cell from secretion
- Direct immunofluorescent antibody (IFA) staining or ELISA, PCR
Chest Xray:
- Hyperinflated lung due to airways obstruction, air trapping and focal atelectasis (arterial desaturation)
- Increased interstitial marking and peribronchiol cuffing
Blood gas analysis:
- In severe cases show lowered arterial oxygen and raised CO2 tension
ECG, ECHO:
- May display arrhythmias or cardiomegaly
MANAGEMENT:
- Supportive (viral) provide adequate fluid (NG/IV) to maintain hydration and monitor for apnea (infant)
- Humidified O2 delivered via nasl cannulae determined by pulse oximetry
- Ribavirin:Antiviral agent of choice
- Mist/ antibiotics/ steroids not helpful
- Nebulised bronchodilator (salbutamol/ipratropium) often used but not reduce severity / illness duration
- Prophylaxis- good hand hygiene and monoclonal antibody prophylaxis (im palivizumab)
Exam Important
- Fever and mild respiratory distress, wheeze and exaggerated breathlessness with hyperluscency in Chest x-ray & obstructive pattern of PFT suggest Bronchiolitis Obliterans
- RSVH(respiratory syncitial virus or adenovirus) is the commonest etiological agent of Bronchiolitis
- Antiviral agent of choice in a child with bronchiolitis is Ribavirin
- Hyperinflation of the chest is seen in Bronchiolitis
- Intercostal and subcostal retractions and extensive rhonchi on auscultation & chest X-ray showing hyperinflated chest suggest Bronchiolitis
- Bronchiolitis in a self-limiting viral illness secondary to respiratory syncitial virus
- Bronchiolitis predisposes children for later development of asthma
- Egg shell calcification is seen in bronchiolitis
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