Evaluation of lung recovery after static administration of three different perfluorocarbons in pigs

BACKGROUND: The respiratory properties of perfluorocarbons (PFC) have been widely studied for liquid ventilation in humans and animals. Several PFC were tested but their tolerance may depend on the species. Here, the effects of a single administration of liquid PFC into pig lungs were assessed and compared. Three different PFC having distinct evaporative and spreading coefficient properties were evaluated (Perfluorooctyl bromide [PFOB], perfluorodecalin [PFD] and perfluoro-N-octane [PFOC]). METHODS: Pigs were anesthetized and submitted to mechanical ventilation. They randomly received an intra-tracheal administration of 15 ml/kg of either PFOB, PFD or PFOC with 12 h of mechanical ventilation before awakening and weaning from ventilation. A Control group was submitted to mechanical ventilation with no PFC administration. All animals were followed during 4 days after the initial PFC administration to investigate gas exchanges and clinical recovery. They were ultimately euthanized for histological analyses and assessment of PFC residual concentrations within the lungs using dual nuclei fluorine and hydrogen Magnetic Resonance Imaging (MRI). Sixteen animals were included (4/group). RESULTS: In the PFD group, animals tended to be hypoxemic after awakening. In PFOB and PFOC groups, blood gases were not significantly different from the Control group after awakening. The poor tolerance of PFD was likely related to a large amount of residual PFC, as observed using MRI in all lung samples (≈10% of lung volume). This percentage was lower in the PFOB group (≈1%) but remained significantly greater than in the Control group. In the PFOC group, the percentage of residual PFC was not significantly different from that of the Control group (≈0.1%). Histologically, the most striking feature was an alveolar infiltration with foam macrophages, especially in the groups treated by PFD or PFOB. CONCLUSIONS: Of the three tested perfluorocarbons, PFOC offered the best tolerance in terms of lung function, gas exchanges and residuum in the lung. PFOC was rapidly cleared from the lungs and virtually disappeared after 4 days whereas PFOB persisted at significant levels and led to foam macrophage infiltration. PFOC could be relevant for short term total liquid ventilation with a rapid weaning.