Analysis of vancomycin entry into pulmonary lining fluid by bronchoalveolar lavage in critically ill patients

Abstract

Vancomycin penetration into the fluid lining the epithelial surface of the lower respiratory tract was studied by performing fiberoptic bronchoscopy with bronchoalveolar lavage on 14 critically ill, ventilated patients who had received the drug for at least 5 days. The apparent volume of epithelial lining fluid (ELF) recovered by bronchoalveolar lavage was determined by using urea as an endogenous marker. Vancomycin levels in ELF ranged from 0.4 to 8.1 micrograms/ml (mean, 4.5 micrograms/ml), while the mean simultaneous level of the drug in plasma was 24 micrograms/ml (range, 9 to 37.4 micrograms/ml). There was a significant relationship (r = 0.64, P < 0.02) between vancomycin levels in plasma and those in ELF, with a correlation whose slope (0.15) indicated that the blood-to-ELF ratio of drug penetration was 6:1. Using the albumin concentration in ELF as a marker of lung inflammation, we found that vancomycin penetration was higher in patients with ELF albumin values of > or = 3.4 mg/ml than in patients with normal values (< 3.4 mg/ml) (P < 0.02). These results suggest that the vancomycin distribution includes the ELF of the lower respiratory tract at a concentration that is dependent upon the levels in blood and the alveolar capillary membrane protein permeability. These concentrations were well above the MICs for most staphylococci and enterococci.