Utility of bronchoalveolar lavage in diagnosing ventilator-associated pneumonia

Utilidad del lavado broncoalveolar en el diagnóstico de la neumonía asociada a la ventilación mecánica

Ventilator-associated pneumonia is the main cause of infection and death in the intensive care unit. Its diagnosis implies the presence of systemic signs of infection, new or worsened pulmonary infiltrates, and positive bacteriologic tests; however, these are non-specific characteristics that may be caused by multiple circumstances in the critically ill patient. Moreover, late or inadequate initiation of antibiotic therapy also worsens the prognosis and outcome of ventilator-associated pneumonia, and therefore microbiologic information is of vital importance for reducing the gap of empirical treatment.

One invasive technique for obtaining samples of the lower respiratory tract is bronchoscopy with bronchoalveolar lavage or protected brush. Samples are processed to obtain quantitative isolation of germs. Non-bronchoscopic techniques have also been described, including endotracheal aspiration and mini-bronchoalveolar lavage; the cut-points of these techniques, in order that they may be considered positive, are different. The decision concerning the best method for obtaining samples for diagnosing ventilator-associated pneumonia is still controversial, and until now none of them has proven to be superior. At any rate, it is advisable to use the technique that may be readily performed in each center by experienced practitioners who are familiar with the technique. Early and adequate therapy for the management of ventilator-associated pneumonia has shown its importance in many studies that are analyzed in this article. Judicious interpretation of culture results should lead to de-escalation of antibiotic therapy, in order to comply with policies concerning adequate antibiotic use and reduction of mortality.