Stable patients receiving prolonged mechanical ventilation have a high alveolar burden of bacteria

Introduction: In patients receiving prolonged mechanical ventilation (PMV), quantitative bronchoscopic culture has not been validated for the diagnosis of ventilator-associated pneumonia (VAP). Objective: To measure the alveolar burden of bacteria in patients receiving PMV. Setting: Respiratory care units of a university hospital and a long-term care facility. Patients: Fourteen patients requiring PMV without clinical evidence of pneumonia. Measurements: Quantitative culture of BAL, from the right middle lobe and lingula. Results: In 29 of 32 lobes, there was growth of at least one organism at > 10⁴ cfu/mL. Most lobes had polymicrobial growth. Conclusions: Stable patients receiving PMV without clinical pneumonia have a high alveolar burden of bacteria. The bacterial burden in most patients exceeds the commonly accepted threshold for diagnosing VAP. The utility of quantitative bronchoscopic culture in the diagnosis of VAP in this patient population requires further study.