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

Abstract

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 ≥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.

Comparison of Manual and Suction Pump Aspiration Techniques for Performing Bronchoalveolar Lavage in 18 Dogs with Respiratory Tract Disease

“…However, in the present study of dogs with pulmonary disease, only 5 of the 22 low‐retrieval BALF samples had inadequate cell numbers for analysis and half (11/22) still yielded a definitive or supportive cytologic diagnosis. This finding agrees with a report in humans that BALF retrieval of at least 10% of the original aliquot still can reflect alveolar sampling . In general, maximal infusate retrieval should be attempted for any BAL to maximize the likelihood of retrieving alveolar cells.…”

Official American Thoracic Society Technical Standards: Flexible Airway Endoscopy in Children

“…The minimum amount of BAL fluid necessary to perform the typical battery of laboratory tests varies by institution. For adults it is recommended that the minimal total volume retrieved is >30% of the instilled volume (48).…”

Technical Aspects of Bronchoalveolar Lavage: Recommendations for a Standard Procedure

“…In one study of nonbronchoscopic lavage, it was shown that patients with a greater than 5% return of instilled fluid have a higher diagnostic yield. 41 For safety reasons, some feel that the lavage should be stopped if the volume instilled becomes more than 100 mL larger than the aspirated volume. Because this will depend on the volume of the instilled aliquots, the bronchoscopist should be aware of the aspirated volume after each aliquot is instilled.…”