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Dept of Anaesthesiology, Heinrich-Heine-University, Düsseldorf, Germany
CORRESPONDENCE: S.A. Loer, Klinik für Anaesthesiologie, Universitätsklinikum Düsseldorf, Moorenstr. 5, 40225, Düsseldorf, Germany. Fax: 49 2118119639. E-mail: loer@med.uni-duesseldorf.de
Keywords: liquid ventilation, lung, perfluorocarbons, positive pressure ventilation, rabbits
Received: November 28, 2001
Accepted June 18, 2002
During partial liquid ventilation perfluorocarbons are eliminated mainly by evaporation via the airways. The effects of intrapulmonary perfluorocarbon volume, respiratory rate, tidal volume, as well as the level of end-expiratory pressure on perfluorocarbon elimination from isolated lungs, were studied.
Nonperfused rabbit lungs underwent partial liquid ventilation (215 mL·kg1 perfluorocarbon) with variable levels of end-expiratory pressure (010 cmH2O), respiratory rates (1560 breaths·min1) and tidal volumes (3.310.0 mL·kg1). Evaporative loss of perfluorocarbon was determined gravimetrically as rate of change in lung weight.
At constant respiratory settings, intrapulmonary liquid volume determined evaporative loss in a nonlinear fashion. Mean evaporation at a liquid volume of 5 mL·kg1 was 13% lower compared to evaporation at a liquid volume of 15 mL·kg1. Any increase in end-expiratory pressure reduced perfluorocarbon evaporation, e.g. by
In summary, the experiments suggested that evaporative loss of perfluorocarbons during partial liquid ventilation of isolated lungs is increased with increasing intrapulmonary liquid volume, respiratory rate and tidal volume and is reduced in a level-dependent fashion by the application of positive end-expiratory pressure.
50% when end-expiratory pressure was increased from 0 to 10 cmH2O. At constant end-expiratory pressure and perfluorocarbon filling evaporation increased in a linear fashion with increasing respiratory rate and tidal volume.
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