Health & Medical intensive care

Suspicion of Ventilator-Associated Pneumonia

´╗┐Suspicion of Ventilator-Associated Pneumonia
Objectives: To determine the pattern of resolution of classic infectious and respiratory variables in patients with ventilator-associated pneumonia (VAP) and appropriate empirical therapy, depending on the presence of acute respiratory distress syndrome (ARDS). A secondary objective was to identify clinical variables that might be useful for monitoring response to therapy.
Design: Prospective, observational cohort study.
Setting: Medical-surgical intensive care unit.
Patients: Seventy-five episodes of VAP without ARDS were identified and compared with 20 episodes with ARDS at VAP onset. Six episodes were excluded due to in vitro resistance to the initial antibiotic choice and six due to death in the first 72 hrs.
Interventions: None.
Measurements and Main Results: Resolution of fever, Pao2/Fio2 >250 mm Hg, and white blood cell count in episodes of VAP were present in 73.3%, 74.7%, and 53.3% of patients after 3 days of therapy. Indeed, >50% of episodes with the absence of ARDS presented resolution of fever and Pao2/Fio2 >250 within the first day of therapy. In contrast, resolution of radiologic opacities and clearance of secretions (median of 14 and 6 days of resolution) were late events. In patients with ARDS, resolution of fever remained the earliest variable. However, similar to Pao2/Fio2 250 and white blood cell count, fever showed a significantly worse pattern after 3 days of therapy: 45%, 15% and 25%, respectively. Radiologic resolution was an extremely poor indicator, being present in only 10% of ARDS patients after 15 days of follow-up. Failure to improve after 48 hrs of therapy was documented in 65% of ARDS patients and 14.7% of controls ( p < .05).
Conclusions: Measures of oxygenation and core temperature can help physicians to individualize and shorten the duration of antibiotic therapy in VAP episodes. ARDS patients with VAP take twice as long to resolve fever, whereas hypoxemia should be ignored in defining resolution in this subset.

Outcome measures in ventilator-associated pneumonia (VAP) include mortality rates, length of stay, and costs. A large prospective cohort study in adults with VAP in U.S. hospitals suggested that attributable mortality rate was less than previously suspected. However, very little information is available on the time pattern of resolution of infectious and respiratory variables in VAP.

The Infectious Diseases Society of America guidelines suggest 72 hrs of therapy as the time to record failure to improve in patients with community-acquired pneumonia. Sensitivity information from microbiological cultures is usually available in most patients with pneumonia after 48 hrs of therapy; at this point, the patient is usually reassessed and the possibility of practical measures such as de-escalation is discussed. Resolution of infectious variables after follow-up of 27 patients with VAP was first evaluated in 1997. These authors reported that resolution occurred a median of 6 days after diagnosis. Recently, Luna et al. evaluated the performance of the clinical pulmonary infection score and its components to predict risk of death in patients with VAP. Unfortunately, these studies did not report the effect or incidence of acute respiratory distress syndrome (ARDS).

The 1996, American Thoracic Society guidelines and many randomized clinical trials used a 2-wk period as standard length of therapy in most patients with VAP. We prospectively followed a cohort of patients with VAP over 2 wks to determine how the presence of ARDS influences the resolution pattern of VAP. Hypoxemia and radiography are unlikely to improve in 72 hrs in patients with ARDS. Therefore, our hypothesis was that if patients with ARDS are excluded, resolution of VAP can be predicted within the first 72 hrs of therapy. The primary objectives of this study were to establish the pattern of resolution of classic infectious and respiratory variables in patients with VAP with and without ARDS. A secondary objective was to identify variables that can be used to monitor the response.

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