Ventilator-associated pneumonia compucating severe community-acquired pneumonia

Patients(pts) with severe community-acquired pneumonia (SCAP) appear to be prone to ventilator-associated pneumonia (VAP). Risk factors for VAP complicating SCAP have not previously been described. Methods: From 1/1/93 through 12/31/95, all 181 pts admitted to two MICUs with SCAP were prospectively followed. 142 pts received mechanical ventilation (MV). In addition to direct comparison a nested case control comparison was done between SCAP pts who developed VAP and those that did not. All control pts were ventilated ±2 days of cases. A10 point score based on duration of ventilation, age, risk factors for SCAP, APACHE III score, sex, hospital, and causative organism was used. Control pts matched VAP pts on an average of 7 pts with only 2 pts matching as low as 5 pts. Results: 24/142 (16.9%) of ventilated SCAP pts developed VAP. VAP pts were ventilated for an average of 13.5 days (95% CI 10.6-16.5) before the first episode of VAP compared with an average total duration of MV of 8.7 days (7.3-10.2) in non-VAP pts. MV ≥ 10 days (OR 12.7), ARDS (OR 3.79), VAMC admission (OR 6.95), and lack of neutropenia (OR 0.10) were associated with development of VAP. In the case-control study, Caucasians (OR 5.32), empiric treatment (OR 30.0), lack of bronchoscopic diagnosis (OR 4.49), and causative organism, with S. aureus CAP (OR 0.24) least likely, were associated with development of VAP. Since MV a 10 days appeared to be the greatest risk factor, a separate analysis of only pts ventilated a 10 days was also performed. None of the risk factors, including ARDS and empiric treatment, found in the first two analyses remained significant. No antibiotic regimen was associated with VAP in any analysis. VAP complicating SCAP was not associated with an increased mortality (33.3% compared with 37.3% for non-VAP pts). Conclusions: We conclude that the major risk factor for development of VAP as a complication of SCAP is the subsequent duration of mechanical ventilation. While ARDS is more likely to result in MV ≥ 10 days, it does not appear to be an independent risk factor. Also, neither causative organism nor antibiotic regimen appeared to play a significant role in subsequent development of VAP.