Objective: To find an optimal mode of total liquid ventilation (TLV) with respect to the blood gases exchange while minimizing adverse effects of TLV upon circulation. Type of study: Laboratory experiment on animal model. Setting: The laboratory of experimental pathophysiology, Medical Faculty, Masaryk University, Brno. Subjects: 20 laboratory rabbits. Method: After premedication, tracheostomy was performed in all animals. EKG, central venous pressure and arterial pressure were monitored. After initial conventional mechanical ventilation, rabbits were randomly allocated into three groups and total liquid ventilation was started in different modes: manually delivered TLV; ventilator-delivered TLV with initial dose of PFC and equilibration pause; and ventilator-delivered TLV without initial dose of PFC and equilibration pause. We monitored blood gases at the end of initial conventional mechanical ventilation, during TLV and after termination of second period of conventional mechanical ventilation. We recorded heart rate (HR), invasive blood pressure (BP) and central venous pressure (CVP). In the 1st group, we analyzed „expiratory“ liquid for oxygen and carbon dioxide content. Results: Group 1: No changes in pH and paO2, significant rise in paCO2 during TLV, short and non-sustained arrhythmias and hemodynamic instability during initial dose of PFC. Oxygen and carbon dioxide tensions are directly associated with the duration of equilibration pause. Group 2: Severe hypercapnia and acidosis during TLV, severe arrhythmias and hemodynamic instability. Group 3: No significant changes in pH and blood gases, no arrhythmias or hemodynamic instability. Conclusion: Based on blood gases analysis and hemodynamic profile, continuous TLV without equilibration pause seems to be an optimal mode for TLV.

        Key words: total liquid ventilation - acid-base balance - blood gases - adverse effects - experiment