Diagnosis, treatment and prevention of VAP

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Diagnosis, treatment and prevention of VAP

• Dr Andrew Conway Morris
• Clinical Research Fellow
• University of Edinburgh

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Ventilator Associated Pneumonia

• Common
• Pro-longs stays in ITU
• Associated morbidity and mortality
• Difficult to diagnose
• Entirely preventable?

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Why is VAP so common?

• Patients with critical illness are
  immuno-suppressed.
• functional neutropaenia
• ITU acquired infections affect 16-20 of all
  patients admitted, far more common than for
  patients admitted to other areas of the hospital

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Why VAP is common 2

• Endo-tracheal tube - a bug highway
• Sub-glottic pooling of secretions
• Micro-aspiration
• Stress ulcer prophylaxis?
• Inhibition of innate defenses such as cilia and
  cough for clearance of secretions

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Difficulties in diagnosis

• How can you diagnose VAP?
• Clinical diagnosis
• Microbiological diagnosis - non-invasive or
  invasive
• Why bother?

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X-rays
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X-rays
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Temperature, WCC

• Bacteraemia
• Skin infection / cellulitis
• Pneumonia
• Abscess
• Infective endocarditis
• Meningitis
• Urinary tract infection
• Intra-abdominal infections
• Gangrene
• Pyelonephritis
• Infectious colitis
• Septic arthritis
• Viral infection

• Pancreatitis
• Trauma/ hemorrhagic shock
• Aspiration pneumonitis
• ARDS
• Mesenteric ischaemia
• Drug reactions
• Substance abuse
• Auto-immune diseases
• Malignancy
• Transfusion reactions
• vasculitis

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What percentage of those with clinical VAP have
VAP?
20-30
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How useful are endo-tracheal aspirates (ETA)?

• Assume quantitative broncho-alveolar lavage
  cultures are definitive diagnosis.
• From 53 patients with paired samples
• 46 had positive ETA cultures (89)
• Only 11 had positive BAL cultures (21), one had
  a negative ETA sample.
• Sensitivity 90, specificity 14

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Cant we just treat them all?

• Vancomycin and Meropenem are toxic drugs
• They select out organisms (S. maltophila, VRE,
  resistant pseudomonas)
• But if we delay antibiotics patients have worse
  outcomes

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How to diagnose VAP

• Be alert for clinical changes and have a low
  threshold for CXR
• If suspected and no contra-indication perform BAL
  and cultures
• Start broad-spectrum antibiotics
• Rationalise early on basis of culture results

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The future?

• Early diagnostic test - inflammatory cytokine
• Rapid identification of infecting organism
• Only start antibiotics when you need them.

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Prevention

• Immuno-compromised host, surrounded by bacteria
• Head-up tilt - difficult to always do this,
  evidence is reasonable, but so is evidence that
  it is difficult to maintain
• Oral hygiene - makes intuitive sense, little good
  evidence that it makes much difference but
  regular oral suctioning may help

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Prevention

• Chlorhexadine wash/gel - good evidence for this,
  not currently in practice in the UK
• Selective Digestive Decontamination?
• Sub-glottic suction
• Not being on a ventilator!

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Suction port
Sub-glottic pooling
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Summary

• VAP is common
• VAP is difficult to diagnose
• Microbiological cultures by invasive measures are
  more specific than by non-invasive
• Treatment should start promptly and stop promptly

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Summary 2

• VAP is preventable
• Head up tilt
• Sedation holidays and rapid weaning
• Good oral hygiene and pharyngeal suctioning
• Chlorhexadine, Sub-glottic suction?