Too few, too late: submission patterns of bronchoalveolar lavage fluid samples obtained under the suspicion of the diagnosis of ventilator-associated pneumonia

Abstract

Introduction At our hospital, ventilator-associated pneumonia (VAP) is diagnosed by microbiological and cytological analysis of bronchoalveolar lavage (BAL) fluid. Opening hours of the inhouse microbiological laboratory are between 8.00 a.m. and 5.00 p.m. During off-hours a laboratory technician is on call for urgent samples including BAL fluid. The total laboratory workup of the BAL fluid including the differential cell count takes 2 hours. The present study aimed to analyse the day and hour submission patterns of BAL fluid samples. Materials and methods During a 58-month period (January 2000-October 2005), the day and hour of submission of all consecutive BAL fluid samples obtained from patients suspected of VAP were recorded. The diagnosis of VAP was made if quantitative cultures reached ≥ 104 colony forming units/ml and/or if ≥ 2% infected cells were enumerated on May-Grunwald Giemsa stained cytocentifuged preparations. Results A total of 433 BAL fluid samples was included. On week days, a total of 69.8 ± 5.8 samples for each day were submitted, compared with 38 and 46 samples on Saturday and Sunday. For nearly one-half (199, 46.0%) of the samples, the onduty laboratory technician was required: 99 (23.0%) samples arrived within 1 hour before closing, and an additional 100 (23.0%) were submitted after closing. VAP was diagnosed in 168 (38.8%) samples, 92 (54.8%) of these diagnoses were made after closing hours. VAP was diagnosed in 76/220 (34.5%) of samples submitted during opening hours, and tended to be diagnosed proportionally more after closing hours during weekdays (54/129 41.8%) and during weekends (38/84 samples, 45.2%; P = 0.09). Discussion and conclusion The high number of BAL fluids processed after laboratory opening hours is of concern because of the suboptimal working conditions (fatigue, lack of supervision). Technician time spent on these samples puts a strain on the laboratory in terms of costs and absence of the technicians because of legal recuperation. The low number of BAL fluids submitted during the weekends combined with the higher proportion of VAP in these samples points to poor compliance with inhospital guidelines for the diagnosis of VAP and could suggest that we missed a number of (unconfirmed) episodes of VAP.