pneumonia%20-%20hospital-acquired
PNEUMONIA - HOSPITAL-ACQUIRED
Hospital-acquired pneumonia (HAP) is defined as pneumonia occurring ≥48 hours after admission and excluding any infection that is incubating at the time of admission.
Ventilator-associated pneumonia (VAP) is described as pneumonia occurring >48-72 hours after endotracheal intubation and within 48 hours after removal of endotracheal tube.
Early-onset HAP or VAP is the pneumonia occurring within the first 4 days of hospitalization that may be cause by antibiotic-sensitive bacteria that usually carries a better diagnosis.
Late-onset HAP or VAP is the pneumonia occurring after ≥5 days. It is likely caused by multidrug-resistant pathogens associated with increased mortality and morbidity.

Diagnosis

  • The clinical approach to define pneumonia makes use of clinical evidence & radiographic findings
  • Clinical Pulmonary Infection Score (CPIS) is used to quantify clinical, radiographic, microbiologic & physiological findings
    • A threshold score of >6 leads to a diagnosis of hospital-acquired pneumonia (HAP); has a sensitivity of 77% & specificity value of 42%
    • May be useful in selecting patients for short-course antibiotic therapy & monitoring of response to treatment

Assessment

CURB65 Scoring System for Mortality Risk Assessment
  • May be used as a prognostic baseline for patients diagnosed w/ hospital-acquired pneumonia
Prognostic Features (1 point for each feature present)
  • Confusion (abbreviated Mental Test score ≤8 or new disorientation)
  • Increased blood urea nitrogen (≥7 mmol/L)
  • Increased respiratory rate (≥30 breaths/min)
  • Decreased blood pressure (≤90/60 mmHg)
  • ≥65 years old
Stratification:
  • 0 or 1: Low risk (<3% mortality risk)
  • 2: Moderate risk (3-15% mortality risk)
  • 3-5: High risk (>15% mortality risk)

History

  • Thorough history & physical exam are performed to define the severity of the pneumonia
  • They can elicit presence of specific conditions that can have an impact on the likely pathogens
  • Exclude other potential sources of infection

Laboratory Tests

Cultures
  • Should be collected before antibiotics are started or changed
  • Blood
    • Two sets from separate sites
    • If blood cultures (BC) isolate a pathogen, other sites of infection will need to be excluded
  • Sputum, pleural fluid
  • Endotracheal or transtracheal aspirate
Invasive Microbiologic Techniques
  • Usually confined to intubated patients
  • Invasive procedures [eg bronchoscopy w/ protected specimen brushing (PSB) &/or bronchoalveolar lavage (BAL)]
  • Etiologic pathogen is determined if a specimen contains organism(s) above a predetermined threshold concentration
Arterial Blood Gas or Oximetry
  • Generally measured in all patients to determine the severity of illness & the need for supplemental O2 or mechanical ventilation
Other Laboratory Tests
  • Complete blood count (CBC), serum electrolytes, renal & liver function
  • A baseline C-reactive protein may be obtained for assessment of response to therapy 48-72 hours after admission
  • Not useful for determining the etiologic organism
  • May be useful to document presence of organ dysfunction to assist in determining the severity of illness

Imaging

Chest X-ray (CXR)
  • Both posterior-anterior (PA) & lateral views are recommended
  • Helps to identify disease severity & presence of complications (eg effusion, cavitation)

Clinical evidence that new or progressive infiltrate is consistent of pneumonia

  • At least 2 of the following should be present:
    • Fever >38°C
    • Purulent sputum
    • Leukocytosis [WBC >12,000 cells/mm3 (12x109 cells/L)] or leukopenia [WBC <4,000 cells/mm3 (4x109 cells/L)]
  • There is high sensitivity even if only 1 criterion is used, but low specificity is noted for ventilator-associated pneumonia (VAP)
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