PRELIMINARY DATA OF TOTAL LIQUID VENTILATION IN A NORMAL FULL-SIZED SHEEP MODEL

Abstract

In an effort to bring total liquid ventilation (TLV) to clinical application, a prototype ventilator with 4 single piston pumps and 4 conventional membrane oxygenators, simply designed and easily controlled, was tested in an in vivo ful- sized sheep model. TLV was performed in 3 anesthetized and paralyzed sheep (weight range 54–56 Kg). Once all the inclusion criteria were met during gas ventilation (PaO2 > 400mmHg, PaCO2 between 30–45mmHg, and MAP 60 mmHg), liquid ventilation process was started giving an initial fill volume of 30 ml/kg of pre-warmed PFC (FC77), followed by a liquid tidal volume. Respiratory rate was set as 5 breaths per minute, and an I:E ratio of 1:2 using a square wave flow pattern during both phases of ventilation was used; Arterial blood gas; hemoglobin; oxygen saturation; SvO2; cardiac output; systemic and pulmonary arterial blood pressure; heart rate; ventilator pressure, tidal volume, and airway pressure data w assessed and recorded at the beginning of TLV and then every hour. The ventilator's CO2 removal efficiency was assessed by sampling the PFC before and after the oxygenators and calculating the normalized CO2 removal efficiency by the formula: [PPFCCO2in-PPFCCO2out]/ [PPFCCO2in]. This system was tested for 3 hours with stable PaCO2 and PaO2 (see figures below) and no hemodynamic impairment. An averaged CO2 removal efficiency of 80% and an averaged level of 676 mmHg of PFC PO2 were obtained by the 4 membrane oxygenators with a countercurrent sweep gas of 100% oxygen at 5 L/min. No evidence of fluorothorax was observed at the chest gross examination at the end of the experiments; These data suggest the potential of this prototype to support removing CO2 and oxygenating perfluorocarbons during total liquid ventilation in a full sized animal model.Figure