The purpose of the present study was to validate the quantitative culture and cellularity of bronchoalveolar lavage (BAL) for the diagnosis of ventilator-associated pneumonia (VAP). A prospective validation test trial was carried out between 1992 and 1997 in a general adult intensive care unit of a teaching hospital. Thirty-seven patients on mechanical ventilation with suspected VAP who died at most three days after a BAL diagnostic procedure were submitted to a postmortem lung biopsy. BAL effluent was submitted to Gram staining, quantitative culture and cellularity count. Postmortem lung tissue quantitative culture and histopathological findings were considered to be the gold standard exams for VAP diagnosis. According to these criteria, 20 patients (54%) were diagnosed as having VAP and 17 (46%) as not having the condition. Quantitative culture of BAL effluent showed 90% sensitivity (18/20), 94.1% specificity (16/17), 94.7% positive predictive value and 88.8% negative predictive value. Fever and leukocytosis were useless for VAP diagnosis. Gram staining of BAL effluent was negative in 94.1% of the patients without VAP (16/17). Regarding the total cellularity of BAL, a cut-off point of 400,000 cells/ml showed a specificity of 94.1% (16/17), and a cut-off point of 50% of BAL neutrophils showed a sensitivity of 90% (19/20).In conclusion, BAL quantitative culture, Gram staining and cellularity might be useful in the diagnostic investigation of VAP. Correspondence

To investigate the effects of chronic exposure to mercury we studied the red cell antioxidant system in mercury-exposed workers through the evaluation of reduced glutathione, catalase and superoxide dismutase systems. Oftheseworkers, somewerebeingexposedatthetimeand had presented urinary mercury levels considered safe for occupational exposure for at least 3 months prior to the initiation of this study, and others had been on leave for at least 6 months because of intoxication symptoms. Reduced glutathione levels were lower and catalase activity was higher in the workers which were still being exposed, compared to those on leave and controls. No differences were observed between the workers on leave and controls.

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