CONTINUOUS LOW-FLOW TRACHEAL GAS INSUFFLATION DURING PARTIAL LIQUID VENTILATION IN RABBITS

Background: Both partial liquid ventilation (PLV) and tracheal gas ins ufflation are novel techniques for mechanical ventilation. In this stu dy we examined whether PLV superimposed by continuous low-flow trachea l gas insufflation (TGI) offers any advantage to the blood gases and l ung mechanics in normal-lung rabbits compared to the use of PLV only. Methods: Eighteen anesthetized, paralyzed and mechanically ventilated rabbits were used. After obtaining a baseline PaCO2 value between 29 a nd 39 mmHg (3.9 and 5.2 Wa), the animals were assigned to three equal groups according to the ventilation they received - A group: PLV super imposed by TGI; B group: PLV only; and C group: continuous mandatory v entilation (CMV) superimposed by TGI. Serial arterial blood gases, pH and lung mechanics were measured. Results: The animals in each group w ere hemodynamically stable. In the case of the A group, PaO2 continuou sly increased, and PaCO2 stabilized around 40.8+/-5.5 mmHg (5.4+/-0.7 kPa, mean+/-SD, NS). Ln the B group, the tendency for PaO2 to increase was not as definite; PaCO2 continuously increased from 35.2+/-2.3 mmH g (4.7+/-0.3 kPa) to 56.3+/-12.7 mmHg (7.5+/-1.7 kPa, P<0.05) at the e nd of the experiment. In the C group, PaO2 and PaCO2 were stable durin g the observation period. The superimposition of TGI on PLV did not de crease the airway pressures compared to PLV alone. Conclusion: In summ ary, continuous low-flow TGI superimposed on PLV can decrease and stab ilize the PaCO2 elevation caused by the initiation of PLV.