Diagnosis of Gram negative, ventilator associated pneumonia by assaying endotoxin in bronchial lavage fluid

Aim-To investigate the usefulness of assaying endotoxin in non-directed bro nchial lavage fluid (NBL), bronchoscopic bronchoalveolar lavage fluid (BAL) , and sera as a means of diagnosing Gram negative, ventilator associated pn eumonia. Methods-Samples from 64 patients were investigated. Fifty nine BALs and 92 NBLs were assayed in total including specimens taken during 28 episodes of clinical ventilator associated pneumonia (VAP). Results-The concentration of endotoxin in BAL from patients with VAP develo ping within four days of commencing ventilation was significantly higher th an in those without VAP (p = 0.015). There was no significant difference in endotoxin concentration in NBL or serum when comparing patients with and w ithout VAP. A BAL endotoxin concentration of 6 EU/ml yielded the optimal op erating characteristics (sensitivity, 81%; specificity, 87%; positive predi ctive value, 67%; negative predictive value, 95%). However, Gram stain of B AL provided the same information as quickly as the endotoxin assay and is c onsiderably cheaper. Conclusions-Despite its accuracy and rapidity, the BAL endotoxin assay must be shown to alter clinical management and patient outcome to be cost effec tive.