Ventilator Associated Pneumonia (VAP) 

Definition 

Ventilator-Associated Pneumonia (VAP) is a type of nosocomial pneumonia that occurs ≥48 hours after endotracheal intubation and mechanical ventilation. 

It is a subtype of hospital-acquired pneumonia (HAP). 

Epidemiology 

Most common ICU-acquired infection in mechanically ventilated patients. 
Incidence: 10–20% of mechanically ventilated patients. 
Mortality: 20–50% depending on pathogen, patient comorbidities, and timeliness of treatment. 
Risk increases with prolonged ventilation, severity of illness, and poor oral hygiene. 

Pathophysiology 

VAP develops due to micro-aspiration of oropharyngeal or gastric secretions and biofilm formation on endotracheal tubes. 

Key mechanisms: 

Colonization: Oropharyngeal and gastric flora may colonize the upper airway and endotracheal tube. 
Micro-aspiration: Small amounts of secretions enter lower airways despite the cuff. 
Impaired host defences: Sedation, supine positioning, and critical illness decrease cough reflex and mucociliary clearance. 

Common pathogens: 

Early-onset (<5 days): Streptococcus pneumoniae, Haemophilus influenzae, Methicillin-sensitive Staphylococcus aureus (MSSA) 
Late-onset (>5 days): Pseudomonas aeruginosa, MRSA, Acinetobacter spp., Enterobacteriaceae 

Risk Factors 

Patient-related: Advanced age, chronic lung disease, immunosuppression. 
Treatment-related: Prolonged intubation, reintubation, supine positioning, prior antibiotic use. 
Device-related: Subglottic secretions, ventilator circuit contamination. 

Clinical Features 

Signs and symptoms are often nonspecific:
 
Fever or hypothermia 
Purulent tracheal secretions 
Leucocytosis or leukopenia 
New or progressive pulmonary infiltrates on chest X-ray 
Worsening oxygenation (↑ FiO₂, ↑ PEEP) 
Note: Distinguishing VAP from other causes of pulmonary infiltrates in ICU (e.g., ARDS, pulmonary oedema) can be challenging. 

Diagnosis 

Diagnosis is clinical, radiographic, and microbiological. 

Diagnostic criteria (CDC/IDSA guidelines): 

Mechanically ventilated >48 hours 
New or progressive infiltrate on chest X-ray 
At least 2 of the following: 
Fever >38°C 
Leucocytosis (>12,000/mm³) or leukopenia (<4,000/mm³) 
Purulent tracheal secretions 

Microbiological confirmation: 

Endotracheal aspirate culture (≥10⁶ CFU/mL) 
Bronchoalveolar lavage (BAL) (>10⁴ CFU/mL) 
Protected specimen brush (≥10³ CFU/mL) 
Scoring systems: 
CPIS (Clinical Pulmonary Infection Score) – combines clinical, radiographic, and microbiological data; >6 suggests VAP. 
 
Management 

Empiric Antibiotic Therapy 

Start promptly after collecting cultures. 
Choice depends on early vs late onset and local resistance patterns. 
Follow local guidelines 

Early-onset (<5 days, no risk factors for MDR): 

Suggest Ceftriaxone, Ampicillin-sulbactam, Levofloxacin 

Late-onset (>5 days or risk factors for MDR): 

Suggest Antipseudomonal β-lactam (Piperacillin-tazobactam, Cefepime, Meropenem) ± Vancomycin or Linezolid (for MRSA) 

Duration: Usually 7–8 days if patient improves. 

Supportive Care 

Optimize oxygenation and ventilation 
Fluid and hemodynamic management 
Monitor for complications (sepsis, ARDS) 

Prevention (VAP Bundle) 

Elevate head of bed 30–45° 
Daily sedation interruption and assessment for weaning 
Peptic ulcer and DVT prophylaxis 
Oral care with chlorhexidine 
Subglottic suctioning 
Hand hygiene and sterile suction technique 
Minimize ventilator duration if possible 

Complications 

Sepsis and septic shock 
Acute respiratory distress syndrome (ARDS) 
Multi-organ failure 
Increased ICU stay and healthcare costs 

Key Points: 

VAP occurs ≥48 hours after intubation 
Most important risk factor: prolonged mechanical ventilation 
Diagnosis: new infiltrate + clinical signs + microbiological confirmation 
Early empiric antibiotics should cover likely pathogens; adjust based on cultures 
Prevention is better than treatment—VAP bundles are essential