Previous reports of the cellular effects of Perflubron (PFB) demonstrated decreased phagocytosis and free radical production by alveolar macrophages following in vitro exposure to PFB. In vivo data demonstrate reduced pulmonary inflammation during PLV. Concern regarding a subject's susceptibility to nosocomial pneumonia has arisen following these observations. We examined whether PLV with PFB would change colonization of the lung in an experimental nosocomial infection model. We investigated the effects of PFB on bacterial viability. Methods: In vitro study: 1.5 × 108 cfu (colony forming units) of P. multocida grown to log phase were exposed to PFB for 60, 160 or 360 mins at 37°c. Controls were an identical numbers of Pasteurella without PFB. Bacterial growth at the different time points was determined quantitatively and compared to a baseline value. In vivo model: Pathogen-free rabbits were sedated and instrumented for ventilation. Rabbits were assigned to PLV or control groups. PLV was performed during IMV at FiO2 = 1.0 by filling the airway with PFB (Liquivent™, Alliance Pharmaceutical, San Diego)(18 mL/kg or until the fluid meniscus was visible) and replacing evaporative losses. Control rabbits were ventilated identically but without PFB. Previously prepared, cryopreserved aliquots of 108 cfuP. multocida type A3 were administered via ETT to each animal with ventilation continued for 6 additional hours. The lungs were subsequently removed, aseptically minced and homogenized in tissue grinders. Serial dilutions of homogenates were quantitatively cultured in standard fashion. The recovered organisms were typed for species by the clinical microbiology laboratory. In vivo data were analyzed non-parametrically and indexed per gram of lung tissue and are presented as a percent of the innoculum administered. We conclude that 1) PFB does not have a bactericidal effect, and 2) PLV decreases the viable bacteria per gram of tissue, suggesting that PLV with PFB reduces the risk of nosocomial pneumonia by minimizing the colonization of the lung with bacteria following inadvertent inoculation of the airway during routine ICU care.Table
