QUESTION 141
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Ventilator-Associated Pneumonia — Risk Factors, Prevention Bundle, CPIS & De-escalation Define ventilator-associated pneumonia (VAP) and describe the pathogenesis of microaspiration [3]. Outline the VAP prevention bundle components and the evidence for each [4]. Describe the diagnostic approach using CPIS and principles of antibiotic de-escalation [3].
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Q87 - Ventilator-Associated Pneumonia — Risk Factors, Prevention Bundle, CPIS & De-escalation
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Q87 · Paper II · 10 MARKS · Short Notes
Ventilator-Associated Pneumonia — Risk Factors, Prevention Bundle, CPIS & De-escalation
Question: Define ventilator-associated pneumonia (VAP) and describe the pathogenesis of microaspiration [3]. Outline the VAP prevention bundle components and the evidence for each [4]. Describe the diagnostic approach using CPIS and principles of antibiotic de-escalation [3].
Core ConceptVAP is the commonest healthcare-associated ICU infection, affecting 9–27% of ventilated patients. It is predominantly preventable – bundle compliance reduces incidence by 50–70%.
A. Definition, Pathogenesis & Risk Factors3 marks
- Definition: new pneumonia >48h after mechanical ventilation. Early-onset (<5 days): community organisms. Late-onset (≥5 days): MDR hospital organisms.
- Pathogenesis: oropharyngeal colonisation → secretions pool above ETT cuff → microaspiration <1 mL past cuff → bacterial inoculation → pneumonia; also ETT biofilm dislodgement.
- Risk factors: supine position, prolonged ventilation >7 days, NG tube, sedation+NMB, reintubation, prior antibiotics.
B. VAP Prevention Bundle4 marks
| Element | Evidence |
|---|---|
| Head of bed 30–45° | Drakulovic 1999: 8-fold ↓VAP |
| Chlorhexidine 0.12% oral care | ↓VAP incidence (OR 0.67); 2% associated with ↑mortality – use 0.12% |
| Subglottic secretion drainage | Most effective single intervention – ↓VAP 45–50% |
| Daily SAT + SBT | Girard 2008 (ABC trial): 3 fewer ventilator days, ↓1-yr mortality |
| Hand hygiene | Most effective infection control measure – WHO 5 moments |
| Ventilator circuit care | Change only when soiled; HME preferred over heated humidifier |
C. CPIS Diagnosis & De-escalation3 marks
- CPIS: 6 components (temp, WBC, secretions, oxygenation, CXR infiltrates, culture) each 0–2, total 0–12; CPIS ≥6 = likely VAP. BAL with quantitative culture (≥10⁴ CFU/mL) is gold standard.
- De-escalation: initial broad-spectrum empirical therapy → narrow at 24–48h per culture → stop at 7–8 days if improving (Chastre JAMA 2003: 8 = 15 days for non-Pseudomonas); procalcitonin can guide stopping.
Examiner's PearlVAP pathogenesis: microaspiration above ETT cuff. Most effective prevention: subglottic secretion drainage (↓45–50%). CHX 0.12% (not 2%). CPIS ≥6 = likely VAP. Antibiotic de-escalation: 7–8 days (not 15) for non-Pseudomonas VAP.
References: Chastre J, Fagon JY. Am J Respir Crit Care Med 2002;165:867-903. Chastre J et al. JAMA 2003;290:2588-2598. Klompas M. NEJM 2013;368:1472-1475.
