Ventilator associated pneumonia: quality of nonbronchoscopic bronchoalveolar lavage sample affects diagnostic yield

The importance of predefined criteria for acceptable samples of respiratory therapists obtained lower respiratory samples were studied, using a nonbronchoscopic bronchoalveolar lavage (BAL) protocol for ventilated patients in the intensive care unit. Therapists were instructed and asked to follow guidelines for obtaining samples. Over one year, 219 samples were obtained by respiratory therapists. Of these, 115 were considered to be adequate samples using the following criteria: 60 mL of instilled volume, at least 5 mL of fluid aspirated, specimens sent for semiquantitative culture, a differential cell count of <5% bronchial epithelial cells. Overall, 52 samples grew one or more pathogen at >10,000 colony forming units (cfu).mL(-1) of BAL. The most common pathogen was Staphylococcus aureus (S. aureus) (11 samples), although Gram-negative bacilli were the single pathogen in 21 specimens. Of the 115 acceptable samples, 40 (35%) grew > or =1 pathogen at >10,000 cfu.mL(-1). For the 80 not acceptable samples which were sent for appropriate culture, 12 (15%) grew >10,000 cfu.mL(-1) BAL. This difference was significant (Chi-squared=9.44, p<0.01). Nonbronchoscopic bronchoalveolar lavage can be safely performed by respiratory therapists'. The authors recommend that a protocol be used to evaluate the quality of a bronchoalveolar lavage sample in the same manner sputum samples are screened prior to interpretation.