Objective:To determine whether partial liquid ventilation (PLV) affects the risk of nosocomial pneumonia.Study Design:To assessin vitrobacterial adhesion and viability after liquid perfluorocarbon exposure and to assess bacterial recovery after partial liquid ventilationin vivoin rabbits.Setting:University animal research facility.Subjects:Thirty-six New Zealand White rabbits.Interventions:To assess adhesions, radiolabeledEscherichia coliwere exposed to perfluorocarbon, incubated against artificial biosurfaces, and compared with nonexposed controls. Bacterial viabilityin vitrowas assessed by exposing broth suspensions ofPasteurella multocidato perflubron for various times. Controls were run in parallel without exposure. Quantitative cultures were performed to determine viability. We undertook short-term and recoveryin vivoinvestigations. The lungs of treated animals were filled with perflubron (∼18 mL/kg), and the control rabbits were ventilated without perflubron in an identical fashion. Cryopreserved aliquots ofP. multocidawere administered via an endotracheal tube. The short-term study animals were ventilated for 6 hrs before being killed. The recovery animals were ventilated for 2-4 hrs, extubated, and killed 20 hrs later. The lungs were removed, aseptically minced, and homogenized. Serial dilutions of the homogenate were quantitatively cultured by manual counting of colonies on agar plates. The recovered organisms were typed for species by the clinical microbiology laboratory.Measurements and Main Results:The adhesion of bacteria to immobilized bronchoalveolar lavage and human saliva, respectively, was reduced by 65% ± 7% and 66% ± 1% (p< .05; n = 5) after exposure to perflubron and by 63% ± 9% and 68% ± 6% after exposure to FC-77 (p< .05; n = 5); however, adhesion was not affected by exposure to Rimar. There was no difference in bacterial viability between the control and perflubron-exposed bacteria (n = 5). Thein vivostudy demonstrated a ten-fold or greater reduction in the number of recovered bacteria in the partial liquid ventilated group compared with the control group.Conclusions:This study suggests that different perfluorocarbons affect adhesions differently. Perflubron and FC-77 appear to decrease bacterial adhesion, whereas Rimar does not. Rerflubron does not have a direct bactericidal effect. Furthermore, PLV with perflubron decreased the number of viable bacteria per gram of tissue after an intentional inoculation of the airway, suggesting that the risk of nosocomial pneumonia is unlikely to be increased during PLV and may, in fact, be reduced in patients supported with PLV.