Study of the proper management of total liquid ventilation and the development of the system for respiratory suport

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1. Initially, a liquid ventilator was developed which was controlled by volume-controlled with pressure limit mode, and total liquid ventilation was performed with it in rabbits. End-expiratory residual volume (EERV) was proved too excessive during total liquid ventilation at initial experiment when compared with the pressure-volume courve of perfluorocarbon measured with others rabbits.2. Weight-controlling total liquid ventilation with rabbits was carried out. The principal of this ventilation to regulate a tidal volume and the EERV was as follows ; the density of PFC is large and the weight of a liquid ventilated animal varies. Therefore, if a maximum and minimum weight are controlled, it follows that a TV and EERV can be controlled. The EERV was increased during liquid ventilation, but TV and ventilation cycle were kept the same. There was no change in PaO2, SaO2, and hemoglobin concentration, whereas PaCO2 and SvO2 deteriorated as the EERV increased. That is, increase in EERV harm … More s gas exchange as well as circulation. The most physiological level of the EERV was around functional residual capacity of liquid (FRC of liquid : FRCL).3. However, to reach the EERV of ERCL with relatively short time was very difficult. Expiration of PFC needs drawing force due to low recoil property. With conventional expiration such as siphon, troughs appear during expiration. These troughs seem to be caused by airway occlusion which may cause airway bleeding or uneven ventilation. We developed a new expiratory method in which difference for siphon became rapidly smaller as the expiration. Rather smooth expiration became feasible with the method.4. Total liquid ventilation with rabbits was carried out with this method on the condition that the EERV was lept as FRCL and a TV was kept constant small volume, but ventilation rate varied. The PaO2 and PaCO2 improved rate-responsively without metabolic acidosis.5. Total liquid ventilation with rabbits was considered that it was impossible to keep both PaCo2 and SvO2 physiologically. The research proved that there was a possibility that the total liquid ventilation could be maintained in difficult cases such as rabbits, and that the results might deny the conventional view for total liquid ventilation : total liquid ventilation must be maintained with large TV and small rate. Less