Liquid ventilation innovations in ventilatory management.

The goal of mechanical ventilation is to maintain adequate gas exchange by opening and stabilizing alveolar units with minimal detriment to the pulmonary and circulatory systems. The optimal ventilatory strategy may be difficult to achieve, especially in patients with respiratory failure. Total liquid ventilation is a process whereby a liquid perfluorocarbon (PFC) replaces both the functional residual capacity and the tidal volume within the lung. Gas exchange is accomplished by mechanically assisted inspiration and expiration of tidal volumes of the liquid using a liquid ventilator. The PFC liquid is then oxygenated and purged of carbon dioxide by a membrane lung. Perfluorocarbons are excellent media for gas exchange due to their extraordinary gas solubility and diffusibility of oxygen and carbon dioxide. Partial liquid ventilation (PLV) is a modified method of the total liquid ventilation technique. In PLV, a functional residual capacity of PFC liquid is maintained in the lung, and the patient is ventilated with a conventional gas mechanical ventilator. Studies of the acute respiratory distress syndrome in animal models and in human series have demonstrated encouraging results using PLV and PFC. The high density, low surface tension, and other qualities of PFC in the setting of PLV may offer a highly innovative approach that can be directed toward the management of patients in respiratory failure.