Managing Hospital Acquired Pneumonia / Ventilator Associated Pneumonia in the ICU

By Adem Lewis / in , , , , , , , , , , , , , , , , , , /

Patient AH is an elderly woman with
chronic lung and cardiac disease admitted to the ICU following a stroke. On day 6, AH developed a productive cough,
decreased air entry bilaterally and lethargy. Her O2
Sat was 87 percent on 15 litres by face mask.
She was febrile, short of breath and her blood pressure
had dropped. Her white count was elevated and a chest
x-ray showed a new infiltrate. Sputum and blood samples were sent and
AH was diagnosed with hospital-acquired pneumonia or HAP. HAP is the second most common
hospital-acquired infection and occurs anywhere in the hospital. In the ICU
intubated patients develop ventilator-associated pneumonia or VAP. Hap is defined as a pneumonia that
develops more than 48 hours after admission, while a diagnosis of VAP requires
patients to have been mechanically ventilated for more than 48 hours at the time of
infection onset. Like all pneumonia syndromes, the diagnosis
is based on the appropriate constellation of clinical signs and symptoms and can
mimic other syndromes, like heart failure, or
pulmonary embolism. A scoring tool such as the Clinical
Pulmonary Infection Score (CPIS) can aid in the diagnosis of HAP or
VAP, and a score greater than six correlates
with the presence of high bacterial counts in the lungs. It can be used to risk stratify patients
and to guide both starting and stopping antibiotics. Once appropriate respiratory samples have been sent for culture, prompt initiation of appropriate empiric
antibiotics is essential for good patient outcomes. The core bugs in HAP or VAP are the usual
respiratory culprits — Streph. pneumo, and H. flu – plus Staph. aureus and some gram-negative bugs — like E coli
Enterobacter species, or Klebsiella species or proteus. To identify target bugs, guidelines place emphasis on the duration of time in
hospital prior to the onset of infection. The longer the time in hospital the
greater the likelihood of colonization. There are risk factors for infection with more difficult to treat
organisms, such as Pseudomonas, MRSA and ESBLs. These risk factors include recent
hospital admissions, antibiotic use, immunosuppression, and known colonization with any of these
organisms. Empiric therapy should target the core bugs and account for these risk factors. Combination therapy for Pseudomonas
infections is common but not supported by the literature. Only if you are worried about
pseudomonas or other multi-drug resistant organisms is it reasonable to start with empiric
combination therapy. For most patients a single antimicrobial
is sufficient. Once you’re a bug identified or if
cultures remain negative at 48 hours, narrow or target therapy for the
remaining treatment. Our patient AH was admitted from home
for six days, and she hasn’t been on antibiotics
during her admission. However, if she had been intubated since
admission she would be considered a VAP and at risk of infection with more difficult to treat bugs. Seven days of antibiotics should be
sufficient to treat most cases of HAP and VAP. 14 days, minimum, is recommended to treat
bacteremic S. aureus pneumonia. Key messages; start antibiotics promptly, target core bugs, consider patient risk factors;
combination therapy should be tailored once culture results are available; treat most patients for seven days.

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