Formal Centers for Disease Control and Prevention (CDC) and the National Healthcare Safety Network (NHSN) definitions of Ventilator Associated Pneumonia (VAP) is laborious and time consuming, resulting in difficulty tracking VAP rates. Diagnosis by invasive methods requires considerable commitment of resources and the overall mortality benefit from this approach has not been demonstrated. We wished to determine whether a more limited data set would track CDC/NHSN case finding definitions with sufficient fidelity to allow its use in surveillance and evaluation of interventions.
We used the respiratory care database of Grady Memorial Hospital to identify all intensive care patients receiving mechanical ventilation for 72 hours or more between February 2007 and July 2007. Electronic radiology reports were reviewed for a randomly selected 25% sample of eligible patients (n = 176, 1661 ventilator days) to identify those patients with new, persistent, or progressive pulmonary infiltrates (n = 50). We then examined the available hospital electronic records for microbiology, hematology, and arterial blood gas results. Among the patients with pulmonary infiltrates, we defined a VAP case as having any two of the following within 48 hours of the index chest film: positive culture from a lower respiratory tract sample, white blood cell count < 4000 or > 12000, or significant deviation of PaO2 from preceding or succeeding baseline.
32 cases (19.3/1000 ventilator days) were identified by simplified index. Complete medical records of all patients with abnormal chest x-rays were then reviewed and cases were defined according to CDC/NHSN criteria. 44 cases (26.5/1000 ventilator days) were identified, significantly more than the proposed simplified index. (Χ2 = 7.82, p = .005) The simplified index, however, successfully tracked changes in the CDC/NHSN VAP rate. (Wilcoxon signed rank, p = 0.041).
Where adequate resources are unavailable to adhere to CDC/NHSN case definitions, a more restricted data set easily retrievable from hospital electronic records reflects changes in VAP rate over time.
A smaller data set may be used to track changes in VAP rates when complete data collection is beyond the resources of an individual institution.
Edwin Eno Omohwo, No Financial Disclosure Information; No Product/Research Disclosure Information