Aspiration Pneumonia

I. Introduction & Definitions

Aspiration is the inhalation of oropharyngeal or gastric contents into the lower respiratory tract. It leads to three distinct clinical syndromes:

1. Chemical Pneumonitis (Mendelson’s Syndrome): Acute lung injury from sterile, acidic gastric contents.
2. Bacterial Aspiration Pneumonia: Infection resulting from aspiration of bacteria from the oropharynx.
3. Mechanical Obstruction: Aspiration of particulate matter (fluids/solids).

II. Predisposing Conditions (Risk Factors)

Aspiration occurs when protective airway reflexes (cough, glottic closure) are compromised or overwhelmed.

1. Neurological (Most Common)

• Central Nervous System: Cerebral Palsy (pseudobulbar palsy), hypoxic-ischemic encephalopathy, intracranial hemorrhage.
• Neuromuscular Disorders: Spinal Muscular Atrophy (SMA), muscular dystrophies, myopathies (poor swallow coordination).
• Altered Sensorium: Seizures, post-ictal state, coma, general anesthesia/sedation.

2. Anatomical Anomalies

• Laryngeal/Tracheal: Laryngeal cleft, laryngomalacia (severe), H-type Tracheoesophageal Fistula (TEF).
• Oral/Pharyngeal: Cleft palate, macroglossia (Down syndrome), Pierre Robin sequence.

3. Gastrointestinal

• Gastroesophageal Reflux Disease (GERD): Severe reflux overcoming lower esophageal sphincter pressure.
• Obstruction: Esophageal stricture, achalasia, vascular ring (dysphagia lusoria).

4. Iatrogenic/Mechanical

• Nasogastric (NG) Tubes: Keeps the gastroesophageal junction open and disrupts the anti-reflux barrier.
• Tracheostomy: Desensitizes the larynx and interferes with glottic closure pressure.

III. Pathophysiology & Microbiology

• Chemical Pneumonitis: Acid (pH <2.5) causes immediate alveolar epithelial damage $\to$ edema $\to$ hemorrhage (Flash pulmonary edema).
• Bacterial Pneumonia: Depends on the inoculum.
  • Community-Acquired: Strep. pneumoniae, Staph. aureus, H. influenzae. (Anaerobes are less common than previously thought in children).
  • Hospital-Acquired/Chronic: Gram-negative enteric bacilli (Pseudomonas, Klebsiella) and Anaerobes (Bacteroides, Peptostreptococcus).

IV. Clinical Features

Acute Aspiration:

• History of choking/coughing while feeding or vomiting.
• Sudden onset respiratory distress, tachypnea, cyanosis.
• Fever (may be delayed in chemical pneumonitis).

Chronic/Recurrent Aspiration:

1. Respiratory Symptoms

• Recurrent Pneumonia: Frequent episodes of lower respiratory tract infection, often in dependent lobes.
• Chronic Cough/Wheeze: Often misdiagnosed as "Difficult Asthma" unresponsive to standard bronchodilators/steroids.
• Purulent Sputum: Suggests bronchiectasis (sequelae).
• Morning Symptoms: Wet cough or congestion upon waking (night-time micro-aspiration).

2. Feeding & General Symptoms

• Feeding Difficulties: Choking, gagging, or coughing during meals; prolonged feeding times (>30 mins).
• Failure to Thrive (FTT): Poor weight gain due to caloric insufficiency (fear of eating) or increased energy expenditure from chronic breathing work.
• Wet Voice: "Gurgly" voice quality after feeding.

V. Diagnosis

1. Radiology (Chest X-Ray)

Infiltrates occur in dependent lung segments based on gravity:

• Supine (Bed-ridden): Right Upper Lobe (posterior segment) or Right Lower Lobe (superior segment).
• Upright/Sitting: Right Lower Lobe (basal segments).
• Chronic: Diffuse interstitial changes or bronchiectasis.

2. Identifying the Cause

• Videofluoroscopic Swallow Study (VFSS): Gold standard to detect oropharyngeal dysphagia and silent aspiration.
• Salivagram (Radionuclide): To detect aspiration of saliva.
• Bronchoscopy: To rule out TEF or retrieve foreign material.
• BAL (Bronchoalveolar Lavage): Lipid-laden macrophages indicate chronic aspiration (low specificity).

VI. Management

1. Acute Management

• Airway: Suctioning (immediate).
• Oxygenation: $O_2$ therapy; intubation if respiratory failure ensues.
• Antibiotics:
  • Chemical Pneumonitis: Antibiotics are NOT indicated immediately (sterile inflammation). Start only if fever/infiltrates persist >48 hours (secondary infection).
  • Bacterial Pneumonia:
    • Community: Amoxicillin-Clavulanate or Ceftriaxone.
    • Hospital/Severe: Clindamycin (excellent anaerobe coverage) or Piperacillin-Tazobactam.
• Corticosteroids: NOT recommended (no benefit in outcome).

2. Prevention of Recurrence (Chronic Management)

The goal is to protect the airway while maintaining adequate nutrition. Management is multidisciplinary (Pediatrician, Speech Therapist, Surgeon).

1. Conservative & Feeding Modifications (First Line)

• Positioning: Feed in an upright position (45–90°) and maintain for 30 minutes post-feeds.
• Thickening: Use of commercial thickeners (e.g., starch/gum-based) to increase bolus viscosity (easier to control than thin liquids).
• Texture Modification: Pureed or soft solids based on VFSS findings.
• Pacing: Slow feeding with frequent breaks.

2. Medical Management

• Oral Hygiene: Critical. Reducing the bacterial load in the mouth reduces the risk of pneumonia even if aspiration occurs.
• Anti-Reflux Therapy: Proton Pump Inhibitors (PPIs) or H2 blockers if GERD is confirmed.
  • Note: Acid suppression changes the pH of the aspirate but does not prevent the volume of aspiration.
• Airway Clearance: Chest physiotherapy and suctioning for chronic secretions.
• Glycopyrrolate: To reduce excessive salivary secretions (drooling) contributing to aspiration.

3. Surgical Management

Indicated when conservative measures fail and respiratory health/growth is compromised.

• Enteral Access (Bypassing the Swallow):
  • Gastrostomy (PEG): Preferred for long-term feeding support.
  • Jejunostomy: If severe reflux persists despite gastrostomy.
• Anti-Reflux Surgery:
  • Nissen Fundoplication: Often combined with PEG if GERD is the primary driver of aspiration.
• Airway Separation (Last Resort):
  • Tracheostomy, Laryngotracheal separation, or Laryngeal diversion (rare, for intractable life-threatening aspiration).

VI. Prognosis

• Depends on the reversibility of the underlying cause.
• Chronic aspiration is the leading cause of death in children with severe cerebral palsy.
• Early intervention prevents irreversible lung fibrosis and bronchiectasis.

VIII. Complications

1. Lung Abscess (Necrotizing pneumonia).
2. Empyema.
3. Bronchiectasis (sequelae of recurrent aspiration).
4. Chronic Lung Disease (Fibrosis).