ventilator-associated pneumonia

Introduction

Pneumonia that develops > 48-72 hours after initiation of mechanical ventilation.

Etiology

risk factors

• mechanical ventilation, endotracheal intubation
  • longer duration of mechanical ventilation
• advanced age (>= 70 years of age)
• depressed level of consciousness
• pre-existing lung disease (COPD)
• immunosuppression
• malnutrition
• supine position
• enteral nutrition
• risk factors for antibiotic-resistant organisms
  • concurrent septic shock
  • preceding ARDS
  • >= 5 days of preceding hospitalization
  • preceding renal replacement therapy
  • intravenous antibiotics within 90 days

Epidemiology

• 10 % of mechanically ventilated patients
  • incidence unchanged 2005-2013
• 55% of ventilator-associated pneumonia may be preventable

Clinical manifestations

• fever (> 38.0 C)
• increased respiratory secretions, purulent sputum, or change in character of sputum
• cough, dyspnea or tachypnea
• rales or bronchial breath sounds
• worsening gas exchange
• delirium in the elderly

Laboratory

• complete blood count may show leukocytosis with left shift or leukopenia
• culture of tracheal aspirate
• blood cultures
• arterial blood gas [[[A475720|paO2/FiO2]] < 240] &/or decrease in SaO2

* also see ARUP consult

Diagnostic procedures

• bronchoscopy may be useful for obtaining a specimen for culture
• lung biopsy in rare cases for obtaining a specimen for culture

Radiology

• new or progressive infiltrate on chest X-ray
• consoidation or cavitation

Management

• antibiotics, guided by culture & antimicrobial sensitivity
  • multiple antibiotic resistance is common
  • 8 days of therapy equivalent to 15 days*
    • 6 days of therapy equivalent to 14 days*
  • 1 week (7 days) of therapy*
  • optimal duration of therapy for Pseudomonas pneumonia is 7 days
    • Pseudomonas & other gram-negative bacilli may require a longer duration of therapy (10-14 days); apparently not so
  • empiric therapy should cover Staphylococcus aureus, Pseudomonas aeruginosa, other non-fermenting gram-negative bacteria & MRSA if risk factors
    • ceftazidime, levofloxacin plus vancomycin
    • cefepime, ciprofloxacin* or levofloxacin plus vancomycin
      • two agents of different classes to cover Pseudomonas - single agent appropriate if antibiotic sensitivity known
  • carbapenems are appropriate for empiric therapy due to extended spectrum beta lactamase producing gram-negative bacilli
    • meropenem vaborbactam & imipenem relebactam FDA-approved
  • other FDA-approved antibacterial agents
    • ceftobiprole, ceftolozane tazobactam, cefiderocol
  • see pneumonia
  • if patient does not improve within 3 days of appropriate antibiotic therapy, consider alternate diagnosis or unrecognized source of infection
    • consider mycoses, candidemia if Candida isolated from not urinary source
      • add coverage with caspofungin or other echinocandin
• supportive care
  • prolonged mechanical ventilation
  • intensive care unit
• prevention
  • hand washing before & after patient contact
  • avoid nasal intubation & nasogastric tube
  • maintain head at >= 30 degree position (30-45 degrees)
  • minimize duration of mechanical intubation
    • daily assessment of readiness for extubation
      • follow daily weaning protocols to expedite extubation
  • conversion of tracheostomy when ventilation is needed longer term
  • proper endtracheal tube cuff pressures to prevent aspiration from gastroesophageal reflux
  • enteral rather than parenteral feeding
  • glycemic control in diabetics
  • minimize sedation
  • oral hygiene: chlorhexidine mouth rinse & subglottic suction
    • toothbrushing associated with lower risk of ventilator-associated pneumonia
  • early mobility
  • data on use of probiotics to prevent ventilator-associated pneumonia conflicting

* ciprofloxacin is not a respiratory fluoroquinolone, but it does penetrate into lung tissue & may be the most effective fluoroquinolone against Pseudomonas

* not due to non-fermenting Gram-negative bacilli (Pseudomonas, Stenotrophomonas maltophilia, Acinetobacter spp*)

* 8 days of therapy adequate for Acinetobacter

More general terms

• nosocomial pneumonia

Additional terms

• mechanical ventilation (assisted ventilation)