A prototype of a liquid ventilator using a novel hollow-fiber oxygenator in a rabbit model.
OBJECTIVE
A functional total liquid ventilator should be simple in design to minimize operating errors and have a low priming volume to minimize the amount of perfluorocarbon needed. Closed system circuits using a membrane oxygenator have partially met these requirements but have high resistance to perfluorocarbon flow and high priming volume. To further this goal, a single piston prototype ventilator with a low priming volume and a new high-efficiency hollow-fiber oxygenator in a circuit with a check valve flow control system was developed.


METHODS
Prospective, controlled animal laboratory study.


METHODS
Research facility at a university medical center.


METHODS
Seven anesthetized, paralyzed, normal New Zealand rabbits


METHODS
The prototype oxygenator, consisting of cross-wound silicone hollow fibers with a surface area of 1.5 m2 with a priming volume of 190 mL, was tested in a bench-top model followed by an in vivo rabbit model. Total liquid ventilation was performed for 3 hrs with 20 mL.kg(-1) initial fill volume, 17.5-20 mL.kg(-1) tidal volume, respiratory rate of 5 breaths/min, inspiratory/expiratory ratio 1:2, and countercurrent sweep gas of 100% oxygen.


RESULTS
Bench top experiments demonstrated 66-81% elimination of CO2 and 0.64-0.76 mL.min(-1) loss of perfluorocarbon across the fibers. No significant changes in PaCO2 and PaO2 were observed. Dynamic airway pressures were in a safe range in which ventilator lung injury or airway closure was unlikely (3.6 +/- 0.5 and -7.8 +/- 0.3 cm H2O, respectively, for mean peak inspiratory pressure and mean end expiratory pressure). No leakage of perfluorocarbon was noted in the new silicone fiber gas exchange device. Estimated in vivo perfluorocarbon loss from the device was 1.2 mL.min(-1).


CONCLUSIONS
These data demonstrate the ability of this novel single-piston, nonporous hollow silicone fiber oxygenator to adequately support gas exchange, allowing successful performance of total liquid ventilation.
Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
Stefano
S
Tredici
Eisaku
E
Komori
Akio
A
Funakubo
David O
DO
Brant
Joseph L
JL
Bull
Robert H
RH
Bartlett
Ronald B
RB
Hirschl
D000818:Animals; D001802:Blood Substitutes / Q000627:therapeutic use; D004867:Equipment Design; D005260:Female; D005466:Fluorocarbons / Q000627:therapeutic use; D021061:Liquid Ventilation / Q000295:instrumentation*; D008297:Male; D023421:Models, Animal; D010106:Oxygenators; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D011817:Rabbits
D001802:Blood Substitutes; D005466:Fluorocarbons; C429307:fluorocarbon 77